APPENDIX A – HIERARCHY OF EVIDENCE · Appendix A – Hierarchy Of Evidence ... Record linkage study. ... by centralized VA patient treatment file data versus hospital-based chart

APPENDIX A – HIERARCHY OF EVIDENCE

Appendix A – Hierarchy Of Evidence

Level of Evidence Study Design

I Evidence obtained from a systematic review of all relevant randomised controlled trials.

II Evidence obtained from at least one properly designed randomised controlled trial.

III-1 Evidence obtained from well-designed pseudo-randomised controlled trials (alternate allocation or some other method).

III-2

Evidence obtained from comparative studies (including systematic reviews of such studies) with concurrent controls and allocation not randomised, cohort studies, case-control studies, or interrupted time-series with a control group.

III-3 Evidence obtained from comparative studies with historical control, two or more single arm studies, or interrupted time series without a parallel control group.

IV Evidence obtained from case-series, either post-test or pre-test/post-test.

APPENDIX B – EXCLUDED STUDIES

Excluded Studies The following articles were excluded from the methodological assessment as outlined in the methods section of the review.

Abdominal Aortic Aneurysm Study Reason for exclusion Aker J. Safety of ambulatory surgery. Journal-of-PeriAnesthesia-Nursing 2001; 16(6): 353-358.

No applicable AAA volume outcome data

Anderson PL, Gelijns A, Moskowitz A, Arons R, Gupta L, Weinberg A, Faries PL, Nowygrod R, Kent KC. Understanding trends in inpatient surgical volume: Vascular interventions, 1980-2000. Journal of Vascular Surgery 2004; 39(6): 1200-1208.

Trend analysis of overall surgical volume, no comparative data

Beattie DK, Rodway A, Ainley T, Davies AH. Implications of ITU bed non-availability and the centralisation of vascular services in the treatment of ruptured abdominal aortic aneurysm. Current UK practice. European Journal of Vascular and Endovascular Surgery 2002; 24(6): 553-554.


Chappel AR, Zuckerman RS, Finlayson SRG. Small rural hospitals and high-risk operations: How would regionalization affect surgical volume and hospital revenue? Journal of the American College of Surgeons 2006; 203(5): 599-604.


Cowan Jr JA, Dimick JB, Henke PK, Huber TS, Stanley JC, Upchurch Jr GR. Surgical treatment of intact thoracoabdominal aortic aneurysms in the United States: Hospital and surgeon volume-related outcomes. Journal of Vascular Surgery. 2003; 37(6): 1169-1174.

Thoracoabdominal aneurysms, different to abdominal aortic aneurysms.

De Souza VC and Strachan DP. Relationship between travel time to the nearest hospital and survival from ruptured abdominal aortic aneurysms: Record linkage study. Journal of Public Health. 2005; 27(2): 165-170.


Dias NV, Ivancev K, Malina M, Resch T, Lindblad B, Sonesson B. Does the wide application of endovascular AAA repair affect the results of open surgery? European Journal of Vascular and Endovascular Surgery 2003; 26(2): 188-194.


Dueck AD, Kucey DS, Johnston KW, Alter D, Laupacis A. Survival after ruptured abdominal aortic aneurysm: Effect of patient, surgeon, and hospital factors. Journal of Vascular Surgery 2004a; 39(6): 1253-1260.

Comparison of outcomes for surgery types, not volume

Dueck AD, Kucey DS, Johnston KWW, Alter D, Laupacis A. Long-term survival and temporal trends in patient and surgeon factors after elective and ruptured abdominal aortic aneurysm surgery. Journal of Vascular Surgery 2004b; 39(6): 1261-1267.

Trend analysis with no reported comparative data

Forbes TL. A cumulative analysis of an individual surgeon's early experience with elective open abdominal aortic aneurysm repair. American Journal of Surgery 2005; 189(4): 469-473.


Study Reason for exclusion Forbes TL, De Rose G, Harris KA. A CUSUM analysis of ruptured abdominal aortic aneurysm repair. Annals of Vascular Surgery 2002; 16(5): 527-533.


Forbes TL, Lawlor D, DeRose G, Harris KA. Examination of the trend in canada toward geographic centralization of aneurysm surgery during the endovascular era. Annals of Vascular Surgery 2006; 20(1): 63-68.


Guzzo MH, Landercasper J, Boyd WC, Lambert PJ. Outcomes of complex gastrointestinal procedures performed in a community hospital. WMJ (Madison, Wis.). 2005; 104(6): 30-34.


Heller JA, Weinberg A, Arons R, Krishnasastry KV, Lyon RT, Deitch JS, Schulick AH, Bush HL, Kent KC. Two decades of abdominal aortic aneurysm repair: Have we made any progress? Journal of Vascular Surgery 2000; 32(6): 1091-1098.


Kazmers A, Striplin D, Jacobs LA, Welsh DE, Perkins AJ. Outcomes after abdominal aortic aneurysm repair: Comparison of mortality defined by centralized VA patient treatment file data versus hospital-based chart review. Journal of Surgical Research 2000; 88(1): 42-46.


Lawrence PF, Gazak C, Bhirangi L, Jones B, Bhirangi K, Oderich G, Treiman G. The epidemiology of surgically repaired aneurysms in the United States. Journal of Vascular Surgery 1999; 30(4): 632-640.


Lucas FL, Stukel TA, Morris AM, Siewers AE, Birkmeyer JD. Race and surgical mortality in the United States. Annals of Surgery 2006; 243(2): 281-286.


Nesi F, Leo E, Biancari F, Bartolucci R, Rainio P, Satta J, Rabitti G, Juvonen T. Preoperative risk stratification in patients undergoing elective infrarenal aortic aneurysm surgery: Evaluation of five risk scoring methods. European Journal of Vascular and Endovascular Surgery 2004; 28(1): 52-58.


Peppelenbosch N, Geelkerken RH, Soong C, Cao P, Steinmetz OK, Teijink JAW, Lepantalo M, De Letter J, Vermassen FEG, DeRose G, Buskens E, Buth J. Endograft treatment of ruptured abdominal aortic aneurysms using the talent aortouniiliac system: An international multicenter study. Journal of Vascular Surgery 2006; 43(6): 1111-1121.


Sidhu RS, Ko M, Rotstein L, Johnston KW. Vascular surgery training in general surgery residency programs: The Canadian experience. Journal of Vascular Surgery 2003; 38(5): 1012-1017.


Knee Arthroplasty Study Reason for exclusion Green LB. Sources of variation in readmission rates, length of stay, and operative time associated with rotator cuff surgery. Journal-of-Bone-and-Joint-Surgery (American) 2003; 85A(9): 1784-1789.

Shoulder Arthroplasty

Gutierrez B, Culler SD, Freund DA. Does hospital procedure-specific volume affect treatment costs? A national study of knee replacement surgery. Health Services Research. 1998; 33(3 I): 489-511.

No applicable outcome data

Hasan SS, Leith JM, Smith KL, Matsen FA. The distribution of shoulder replacement among surgeons and hospitals is significantly different than that of hip or knee replacement. Journal of Shoulder and Elbow Surgery 2003; 12(2): 164-169.

Volume data did not include information on outcomes

Jain NB, Guller U, Pietrobon R, Bond TK, Higgins LD. Comorbidities increase complication rates in patients having arthroplasty. Clin Orthop Relat Res 2005;(435): 232-238.

Knee arthroplasty data pooled with other procedures

Lavernia CJ and Guzman JF. Relationship of surgical volume to short-term mortality, morbidity, and hospital charges in arthroplasty. Journal of Arthroplasty. 1995; 10(2): 133-140.

Knee arthroplasty data pooled with other procedures

SooHoo NF, Lieberman JR, Ko CY, Zingmond DS. Factors predicting complication rates following total knee replacement. Journal of Bone & Joint Surgery - American Volume. 2006a; 88(3): 480-485.

No new data

Liver Resection Study Reason for exclusion Dimick JB, Cowan JA, Colletti LM, Upchurch GR. Hospital teaching status and outcomes of Complx Surgical Procedures in the United States. Archives of Surgery 2004; (139:137-141)

Reporting on subgroup from larger publication in 2004

Effect of hospital volume on operative mortality for major cancer surgery. Journal of the National Cancer Institute. 2003a; 95(10): 701.

Commentary – no applicable data

Stat bite: Effect of hospital volume on operative mortality for major cancer surgery. J Natl.Cancer Inst. 2003b; 95(10): 701.


Granger SR, Glasgow RTE, Battaglia J, Lee RM, Scaife C, Shrieve DC, Avrin D, Mulvihill SJ. Development of a dedicated hepatopancreaticobiliary program in a university hospital system. Journal of Gastrointestinal Surgery 2005; 9(7): 891-895.

Comparison of volume over time, no required volume data

Guzzo MH, Landercasper J, Boyd WC, Lambert PJ. Outcomes of complex gastrointestinal procedures performed in a community hospital. WMJ (Madison, Wis.). 2005; 104(6): 30-34.

Liver resection data pooled

Ko CY, Chang JT, Chaudhry S, Kominski G. Are high-volume surgeons and hospitals the most important predictors of inhospital outcome for colon cancer resection? Surgery 2002; 132(2): 268-273.

Not liver resection

Korula J. Higher hospital volume was associated with lower operative mortality and shorter length of stay after hepatic resection. Evidence Based Medicine. 1999; 4(5): 160.


Stone ME, Rehman SU, Conaway G, Sardi A. Hepatic resection at a community hospital. Journal of gastrointestinal surgery. 2000; 4(4) 349-354

Liver resection data pooled

Wang L. The volume-outcome relationship: Busier hospitals are indeed better but why? Journal of the National Cancer Institute. 2003;95(10) 700-702


Oesophagectomy Study Reason for exclusion Bentrem DJ and Brennan MF. Outcomes in oncologic surgery: Does volume make a difference? World Journal of Surgery. 2005; 29(10): 1210-1216.

Narrative review not systematic. Used in background.

Betensky RA, Christian CK, Gustafson ML, Daley J, Zinner MJ. Hospital volume versus outcome: An unusual example of bivariate association. Biometrics. 2006; 62(2): 598-604.

Examination of mathematical analysis of SMR

Casson AG and van Lanschot JJ. Improving outcomes after esophagectomy: the impact of operative volume. J Surg Oncol 2005; 92(3): 262-266.


Chang AC and Birkmeyer JD. The volume-performance relationship in esophagectomy. [Review] [31 refs]. Thoracic Surgery Clinics 2006; 16(1): 87-94.


Chappel AR, Zuckerman RS, Finlayson SRG. Small Rural Hospitals and High-Risk Operations: How Would Regionalization Affect Surgical Volume and Hospital Revenue? Journal of the American College of Surgeons. 2006; 203(5): 599-604.

No applicable study data

Dimick JB, Pronovost PJ, Cowan JA, Lipsett PA. Complications and costs after high-risk surgery: Where should we focus quality improvement initiatives? Journal of the American College of Surgeons 2003; 196(5): 671-678.

No applicable comparative study data

Gillison EW, Powell J, McConkey CC, Spychal RT. Surgical workload and ooutcome after resection for carcinoma of the oesophagus and cardia. British Journal of Surgery. 2002; 89, 344-348

Included Oesophageal and cardia carcinomas together.

Goodney PP, Siewers AE, Stukel TA, Lucas FL, Wennberg DE, Birkmeyer JD. Is surgery getting safer? National trends in operative mortality. J Am Coll Surg 2002; 195(2): 219-227.


Guzzo MH, Landercasper J, Boyd WC, Lambert PJ. Outcomes of complex gastrointestinal procedures performed in a community hospital. WMJ 2005; 104(6): 30-34.

Data pooled with other procedures

Junemann-Ramirez M, Awan MY, Khan ZM, Rahamim JS. Anastomotic leakage post-esophagogastrectomy for esophageal carcinoma: Retrospective analysis of predictive factors, management and influence on longterm survival in a high volume centre. European Journal of Cardio-Thoracic Surgery. 2005; 27(1): 3-7.


Meyer H-J. The influence of case load and the extent of resection on the quality of treatment outcome in gastric cancer. European Journal of Surgical Oncology. 2005; 31(6 SPEC. ISS.): 595-604.

Not oesophagectomy

Neal JM, Wilcox RT, Allen HW, Low DE. Near-total esophagectomy: The influence of standardized multimodal management and intraoperative fluid restriction. Regional Anesthesia and Pain Medicine 2003; 28(4): 328-334.


Padmanabhan RS, Byrnes MC, Helmer SD, Smith RS. Should esophagectomy be performed in a low-volume center? American Surgeon 2002; 68(4): 348-351.


Schrag D, Cramer LD, Bach PB, Cohen AM, Warren JL, Begg CB. Influence of hospital procedure volume on outcomes following surgery for colon cancer. JAMA 2000; 284(23): 3028-3035.

Not oesophagectomy

Shahian DM and Normand S-LT. The volume-outcome relationship: From luft to leapfrog. Annals of Thoracic Surgery. 2003; 75(3): 1048-1058.


Siewert JR and Siess MA. High volume hospital. The connection between number of cases and outcome quality in surgery. Chirurg 2003; 74(4): 278-281.

Literature review

Steyerberg EW, Neville BA, Koppert LB, Lemmens VE, Tilanus HW, Coebergh JW, Weeks JC, Earle CC. Surgical mortality in patients with esophageal cancer: development and validation of a simple risk score. J Clin Oncol. 2006; 24(26): 4277-4284.


Oesophagectomy (Cont.) Study Reason for exclusion Traverso LW, Shinchi H, Low DE. Useful benchmarks to evaluate outcomes after esophagectomy and pancreaticoduodenectomy. American Journal of Surgery 2004; 187(5): 604-608.

Case study

Urschel JD. Esophagectomy volume and operative mortality. J Gastrointest.Surg 1998; 2(5): 492.

Comment

Urschel JD and Urschel DM. The hospital volume-outcome relationship in general thoracic surgery. Is the surgeon the critical determinant? Journal of Cardiovascular Surgery. 2000; 41(1): 153-155.

Case study

van Vliet EPM, Eijkemans MJC, Kuipers EJ, Hermans JJ, Steyerberg EW, Tilanus HW, van der Gaast A, Siersema PD. A comparison between low-volume referring regional centers and a high-volume referral center in quality of preoperative metastasis detection in esophageal carcinoma. American Journal of Gastroenterology 2006; 101(2): 234-242.

Does not compare hospitals performing the same procedure

Prostatectomy Study Reason for exclusion Bianco Jr FJ, Riedel ER, Begg CB, Kattan MW, Scardino PT. Variations among high volume surgeons in the rate of complications after radical prostatectomy: Further evidence that technique matters. Journal of Urology. 2005; 173(6): 2099-2103.

Measure of internal variation, not a comparison between volume groups.

Eastham JA, Kattan MW, Riedel E, Begg CB, Wheeler TM, Gerigk C, Gonen M, Reuter V, Scardino PT. Variations among individual surgeons in the rate of positive surgical margins in radical prostatectomy specimens. Journal of Urology 2003; 170(6): 2292-2295.

Did not report either morbidity mortality or length of stay

Konety BR, Dhawan V, Allareddy V, Joslyn SA. Impact of hospital and surgeon volume on in-hospital mortality from radical cystectomy: Data from the Health Care Utilization Project. Journal of Urology 2005; 173(5): 1695-1700.

Not prostatectomy

Panageas KS, Schrag D, Riedel E, Bach PB, Begg CB. The Effect of Clustering of Outcomes on the Association of Procedure Volume and Surgical Outcomes. Annals of Internal Medicine. 2003; 139(8): 658-665+I44.

No applicable prostatectomy data

Penson DF. Urologic Oncology. 2006; 24(5): 460. Commentary

Van Poppel H, Boulanger SFF, Joniau S. Quality assurance issues in radical prostatectomy. European Journal of Surgical Oncology. 2005; 31(6 SPEC. ISS.): 650-655.

Not comparative study

Ramirez A, Benayoun S, Briganti A, Chun J, Perrotte P, Kattan MW, Graefen M, McCormack M, Neugut AI, Saad F, Karakiewicz PI. High Radical Prostatectomy Surgical Volume is Related to Lower Radical Prostatectomy Total Hospital Charges. European Urology. 2006; 50(1): 58-63.

Did not report either morbidity mortality or length of stay

Scales CD, Jones PJ, Eisenstein EL, Preminger GM, Albala DM. Local cost structures and the economics of robot assisted radical prostatectomy. Journal of Urology 2005; 174(6): 2323-2329.

Comparisons of technique not volume

APPENDIX C – METHODOLOGICAL ASSESSMENT AND

STUDY DESIGN TABLES

Appendix C 1.1: Study design tables – Abdominal Aortic Aneurysm

Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Birkmeyer (2002) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital volume Population Number: Medicare Patients Pn =140,577

Very Low Low Medium High Very High 27 970 27 273 29 029 28 884 27 421

Age: >75

Very Low Low Medium High Very High 44.4 43.8 42.5 42.6 42.2

Hospital Number: Hn =2,819

Very Low Low Medium High Very High 1 900 426 257 156 80

Surgeon Number: Sn = NA Volume Definitions: Hospital:

Very Low Low Medium High Very High Average # p/yr

<17 17-30 31-49 50-79 >79

Surgeon: NA End Points: Morbidity: NR

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1994-1999 Outcome Measures: Operative mortality (Death in-hospital, or before 30 days after AAA) Data Source: Medicare Provider Analysis Review (MEDPAR), and denominator files from the Centre for Medicare and Medicaid Services. Volume estimates were taken from the All-payer 1997 Nationwide Inpatient Sample.

Ruptured or Unruptured: Unruptured Procedure: Elective repair of abdominal aortic aneurysm ICD- 9 Classification:ICD-9-CM NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: Because of the referral of patients to high volume hospitals information was excluded on coexisting conditions identified at previous admissions within the previous 2 weeks Covariates: Age: Adjustment for age 65-69 70-74 75-79 80-84 85-99

Inclusion criteria: Only patients covered for fee for service arrangements Exclusion criteria: Patients who were <65 or >99 Ruptured aneurysm, Thoracoabdominal aneurysm, or both For high volume hospitals information was excluded on coexisting conditions identified at previous admissions within the previous 2 weeks

Appendix C 1.1: Study design tables – Abdominal Aortic Aneurysm (continued) Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria

Birkmeyer (2002) (Cont.) The United States of America

Mortality: See Table 1: Adjusted operative mortality rates

Very Low Low Medium High Very High 6.5 5.2 4.6 4.7 3.9

Length of stay: NR

Race: Black %

Very Low 4.2 Low 2.5 Medium 2.4 High 2.5 Very High 2.4

Sex: Female %


Comorbidities: ≥3 % (Charlson Comorbidity score)


Table 1: Adjusted operative mortality rates

Very Low Low Medium High Very High Observed mortality rate % 7.8 5.9 5.2 5.3 4.4 Unadjusted mortality rate 95% CI

1.0 0.75 (0.69-0.81) 0.66 (0.60-0.72) 0.66 (0.61-0.73) 0.54 (0.49-0.60)

Adjusted mortality rate 95% CI

1.0 0.79 (0.73-0.86) 0.70 (0.64-0.76) 0.71 (0.65-0.78) 0.58 (0.53-0.65)

Appendix C 1.1: Study design tables – Abdominal Aortic Aneurysm (continued)

Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Birkmeyer (2003) The United States of America This study is a likely subpopulation of the Birkmeyer (2002) Study

Hospital Volume and/or Surgeon Volume: Surgeon Volume and Hospital Volume Population Number: Pn = NR Age: >75

Low Medium High 39.4 39.3 40.3

Hospital Number: Hn =NR Surgeon Number: Sn =


Volume Definitions: Hospital: Annual hospital volume

Low Medium High <27.5 27.5-60.5 >60.5

Surgeon:

Low Medium High <8.0 8.0-17.5 >17.5

End Points: Morbidity: NR Mortality: When Surgeon Volume was treated as a continuous variable it was inversely related to operative mortality (P<0.001)

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1998-1999 Outcome Measures: Operative mortality (Death in-hospital, or before 30 days after AAA) Data Source: The main data was extracted from Medicare Provider Analysis Review (MEDPAR), and denominator files from the Centre for Medicare and Medicaid Services. The Centre for Medicare and Medicaid Services.

Ruptured or Unruptured: Unruptured Procedure: Elective repair for Abdominal Aortic Aneurysm ICD- 9 Classification: ICD-9 NR Training Hospital: Adjusted for teaching status Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:> 75 years

Low 46.3 Medium 45.4 High 47.0

Race:


Sex: Female:


Inclusion criteria: NR Exclusion criteria: Patients who were <65 or >99 Ruptured aneurysm, Thoracoabdominal aneurysm, or both Records including invalid surgeon number Surgeons were excluded if they operated on relatively few patients (often 1)


Birkmeyer (2003) (Cont.) The United States of America

Adjusted operative mortality According to surgeon volume


Adjusted operative mortality According to Surgeon and Hospital volume

Surgeon Low Medium High Hospital Low 6.4 5.0 5.2 Medium 6.1 4.3 3.9 High 6.0 4.3 3.6

When Hospital volume was treated as a continuous variable it was inversely related to operative mortality (P<0.001) After adjusting for Surgeon Volume, Higher Hospital Volume remained a significant predictor for decreased mortality. After controlling for High Volume Hospitals, patients treated by Low Volume Surgeons had a higher mortality rate than those treated by High Volume Surgeons. Length of stay: NR

Comorbidities: Charlson score ≥3


Non-elective admission Low: 26.5 Medium: 23.9 High: 22.5

Table 2: Adjusted operative mortality rates among Medicare patients 1998/99 according to total hospital volume relative to the Leapfrog Group Volume Criteria and Surgeon Volume

Hospital Volume <Cutoff Hospital Volume ≥Cutoff No./yr Low Volume Surgeons High Volume Surgeons Overall hospital mean Low Volume Surgeons High Volume Surgeons Overall hospital mean Elective repair of an abdominal aortic aneurysm

50

Proportion of patients 45.3 18.1 17.8 52.5 Mortality 6.4 4.3 5.4 5.8 3.6 4.3


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Birkmeyer (2004) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = NR Age: NR Hospital Number: Hn = NR Surgeon Number: Sn = NA Volume Definitions: Hospital: Low: <50 High >50 Surgeon: NA End Points: Morbidity: NR Mortality: Hospitals which perform <50 procedures per year achieved an in-hospital mortality rate of 5.1%. Hospitals which perform >50 procedures per year achieved an in-hospital mortality rate of 3.8%. Length of stay: NR

Level of Evidence: II III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 2000 Outcome Measures: In-hospital mortality Data Source: Nationwide Inpatient Sample

Ruptured or Unruptured: Unruptured Procedure: Elective Abdominal Aortic Anerurysm Repair ICD- Xx Classification: NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Adjusted not reported Race: Adjusted not reported Sex: Adjusted not reported Admission type: Adjusted not reported Comorbidities: Adjusted not reported

Inclusion criteria: NR Exclusion criteria: NR

Appendix C 1.1: Study design tables – Abdominal Aortic Aneurysm (continued) Authors Procedure Study Design Study Variables Inclusion/Exclusion Criteria

Birkmeyer (2006) United States of America It is likely that a smaller subgroup of patients included in this study Is reported in Birkmeyer (2003)b

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 4349 Age: NR Hospital Number: Hn = NR Surgeon Number: Sn = NA Volume Definitions: Hospital:

Hospitals ranked by procedure volume: 1 (Worst) 2 3 4 5 (Best) Average annual volumes

<11.8 11.8 – 21.5 2.16 – 35.0 35.1 – 57.3 >57.3


Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1994-2001 Outcome Measures: Operative mortality (rate of death before hospital discharge/ within 30 days of index procedure) Data Source: Centre for Medicare and Medicaid Services The Medical Provider Analysis and Review (MEDPAR)

Ruptured or Unruptured: Unruptured Procedure: Elective Abdominal Aortic Aneurysm Repair ICD- 9 Classification: NR Training Hospital: NR Institutional/Environmental Support: Dartmouth Medical School Selective Referral: NR Covariates: Age: Adjusted not reported Gender: Adjusted not reported Race: Adjusted not reported Comorbidities: Adjusted not reported Admission type: Adjusted not reported Social Security income: Adjusted not reported

Inclusion criteria: Patients who underwent one of four procedures targeted by the Leapfrog Group. Patients aged between 65-99 years. Exclusion criteria: Patients with noncancer diagnoses (15%)

Appendix C.1 Study design tables – Oesophagectomy (Continued) Authors Procedure Study Design Study Variables Inclusion/Exclusion Criteria

Birkmeyer (2006) (Cont.) United States of America

Mortality:

Hospitals ranked by risk-adjusted historical mortality 1 (Worst) 2 3 4 5 (Best)

Actual Mortality

(%)

12.3

7.2 4.4 2.7 2.1

Expected Mortality

(%)

5.8 5.7 5.7 5.7 5.9

Hospitals ranked by historical Volume

Average annual

volumes

<11.8 11.8 – 21.5 2.16 – 35.0 35.1 – 57.3 >57.3

Actual Mortality

(%)

7.8 5.9 5.3 5.3 4.3

Expected Mortality

(%)

6.0 5.7 5.7 5.7 5.6


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Dardik (1998) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital volume and Surgeon Volume Population Number: Pn = 527 Age: Mean ± SD 71.9±8.5 Range 39-94 Hospital Number: Hn = Ruptured Abdominal Aortic Aneurysm

Low Medium High 26 13 6

Unruptured Abdominal Aortic Aneurysm


Surgeon Number: Sn = Ruptured Abdominal Aortic Aneurysm


Volume Definitions: Hospital: Ruptured Abdominal Aortic Aneurysm

Low Medium High 10 10-19 >20

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: Na Study Period: 1990-1995 Outcome Measures: In-hospital mortality rate Length of stay Data Source: Maryland Health Services cost Review Commission Database (HSCRC)

Ruptured or Unruptured: Ruptured Procedure: Ruptured AAA repair ICD- 9 Classification: ICD-9-CM Diagnostic code: 441.02, or 441.3 Procedure code: 38.34, 38.44, 38.64, 38.84, 39.54 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: <65 65-69 70-79 ≥80 Race: Adjusted not reported Sex: Adjusted not reported

Inclusion criteria: Diagnostic code: 441.02, or 441.3 Procedure code: 38.34, 38.44, 38.64, 38.84, 39.54 Presence of one of 10 diagnosis-related codes (5, 110—114, 119, 120, 478, or 479) Exclusion criteria: Thoracoabdominal aortic aneurysms, unruptured abdominal aortic aneurysms, aneurysm repair performed secondary to another operation


Dardik (1998) (Cont.) The United States of America


Low Medium High <50 50-99 >100

Volume Definitions: Surgeon: Ruptured Abdominal Aortic Aneurysm

Low Medium High 1-4 5-9 ≥10

End Points: Morbidity: NR Mortality:

Factor n Mortality Rate %

P

Gender Female 108 51.9±4.8 0.33 Male 419 46.3±2.4 Race White 494 48.2±2.3 0.24 Black 28 35.7±9.2 Hypertension Yes 135 33.3±4.1 <0.0001 No 392 52.3±2.5 Diabetes Yes 30 26.7±8.2 0.023 No 497 48.7±2.2 COPD Yes 115 36.5±4.5 0.008 No 412 50.5±2.5 Smoker Yes 10 30.0±15.3 0.35 No 517 47.8±2.2 Cardiac Disease

Yes 80 37.5±5.4 0.07

No 447 49.2±2.4 Renal Disease

Yes 9 44.4±17.6 0.99

No 518 47.5±2.2

Comorbidities: with diagnostic codes Diabetes: 250 Heart disease: 391, 394-398, 402, 404, 411-414, 416,425 Chronic obstructive pulmonary disease: 415.0, 416.8-416.9, 491-494, 496 Renal disease: 585-586, V42.0, V45.1,V56 Hypertension: 401-405 Smoking: 305.1, 491.0, 472.1, 528.6



Mortality:

Regression coefficient

Odds Ratio 95 % CI P

Age 0.959 2.61 1.77-3.84 <0.0001 High volume surgeon

-0.616 0.54 0.33-0.88 0.014

Gender 0.167 1.18 0.75-1.87 0.474 Race -0.234 0.79 0.33-1.89 0.598 Hypertension -0.633 0.53 0.34-0.83 0.006 Diabetes -0.692 0.50 0.21-1.21 0.124 COPD 0.467 0.63 0.40-0.99 0.045 Smoker -0.449 0.64 0.15-2.68 0.540 Cardiac Disease

-0.248 0.78 0.45-1.34 0.369

Renal Disease

-0.198 0.82 0.20-3.39 0.785

Hospital Volume Ruptured Abdominal Aortic Aneurysm

Class n Mortality %±SD Low 147 45.6±4.1 Medium 191 49.2±3.6 High 189 47.1±3.6 P Value 0.80


Class n Mortality (%) Low 63 54.0±6.3 Medium 189 46±3.6 High 275 46.9±3.0 P Value 0.53



Surgeon Volume

Class n Mortality %±SD Low 315 50.8±2.8 Medium 121 47.1±4.6 High 91 36.3±5.1 P Value 0.05

Length of stay: Hospital Volume Ruptured Abdominal Aortic Aneurysm

Class n Length of stay (days) Low 147 14.0±1.3 Medium 191 10.4±1.0 High 189 11.6±0.9 P Value 0.15

Unruptured Abdominal Aortic Aneurysm NR Surgeon Volume Ruptured Abdominal Aortic Aneurysm

Class n Length of stay (days) Low 315 11.7±0.8 Medium 121 11.6±1.0 High 91 12.4±1.8 P Value 0.46

Unruptured Abdominal Aortic Aneurysm NR


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Dardik (1999) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume Population Number: Pn = 2335 Age: Mean (SD), [Range] 70.4±(7.5), [20-93] Hospital Number: Hn = 46

Low Moderate High 30 9 7

Surgeon Number: Sn =

Very low Low Moderate High Very High 71 83 56 6 3

Volume Definitions: Hospital:

Low Moderate High <50 50-99 >100

Surgeon:

Very low Low Moderate High Very High 1 2-9 10-49 50-99 >100

End Points: Morbidity: NR Mortality: Overall operative mortality rate was: 3.5±0.4%

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 01/1990- 12/1995 Outcome Measures: In-hospital mortality rate Length of stay Data Source: Maryland Health Services cost Review Commission (HSCRC)

Ruptured or Unruptured: Unruptured Procedure: Elective surgical repair of AAA ICD- 9 Classification:ICD-9-CM Primary Diagnostic code 441.4 Procedure code for repair; 38.34, 38.44, 38.64, 38.84 or 39.54 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: 70.4±7.5 Female: 71.8±0.3yrs vs. Male: 70.1±0.2yrs (P<0.0001) Black patients were younger than white:68±0.7 years vs. 70.5±0.2 years; P=0.026 Race: White: Black 2192:134 (94%:6%)

Inclusion criteria: Primary Diagnostic code 441.4 Procedure code for repair; 38.34, 38.44, 38.64, 38.84, or 39.54 Presence of either vascular diagnostic related codes; 5, 110-114,119,120,478 or 479 Presence of a descriptive code for elective admission Exclusion criteria: Thoracoabdominal Aortic aneurysms Ruptured aneurysms Aneurysms resultant from other repairs ▪ 527 patients included in

earlier analysis ▪ 539 repairs urgently ▪ 406 repaired emergently ▪ 13 procedures not

classified



Mortality:

Age Group No. of patients Mortality Rate <65 447 2.2%±0.7% 65-69 570 2.5%±0.6 70-79 1072 3.6%±0.6 ≥80 246 7.3%±1.7% P Value 0.0021

Variable No. of Patients Mortality rate % P value Gender Male 510 4.5±0.9 0.17 Female 1825 3.2±0.4 Race White 2192 3.2±0.4 0.046 Black 134 6.7±2.2 Hypertension Yes 893 2.6±0.5 0.08 No 1442 4.0±0.5 Diabetes Yes 168 3.0±1.3 0.99 No 2167 3.5±0.4 Pulmonary disease Yes 733 2.6±0.6 0.14 No 1602 3.9±0.5 Smoker Yes 95 1.1±1.1 0.26 No 2240 3.6±0.4 Cardiac Disease Yes 691 3.2±0.7 0.71 No 1644 3.6±0.5 Renal Disease Yes 17 11.8±8.1 0.11 No 2318 3.4±0.4

Operative mortality rate among blacks was Significantly higher in comparison to whites 6.7±2.2% vs. 3.2±0.4% P=0.046 Sex: Male: Female 1825:510 (78% / 22%)



Influence of hospital volume on mortality

Hospital Class No. of Hospitals No. of Patients Mortality rate% Low 30 679 4.3±0.8 Moderate 9 624 4.2±0.8 High 7 1032 2.5±0.5 P Value 0.08

Influence of surgeon volume on mortality

Surgeon Class No. of Surgeons No. of cases Mortality rate% Very Low 71 71 9.9±3.6 Low 83 369 4.9±1.1 Moderate 56 1200 2.8±0.5 High 6 348 2.9±0.9 Very high 3 344 3.8±1.0 P Value 0.0106

See Table 3: Multivariate analysis of risk factors for operative mortality Length of stay: Overall Length of Stay rate was: 10.6±0.2 days Overall ICU length of Stay rate was: 3.5±0.1 days Female patients had a significantly longer length of stay compared to males: 11.4±0.4 days vs. 10.4±0.2 days(P=0.0004) Female patients had a significantly longer ICU length of stay compared to males: 3.9±0.2 days vs. 3.4 vs. 3.4±0.1 days (P=0.107) Black patients had a significantly longer length of stay compared to White patients: 11.2±0.9 vs. 10.5±0.2 (P=0.026)



White patients had a longer ICU length of stay compared to Black patients: 3.2±0.4 vs. 3.5±0.1 (P=0.108)

Age Group No. of patients Length of Stay <65 447 9.0±0.3 65-69 570 9.5±0.3 70-79 1072 11.3±0.3 ≥80 246 12.9±0.6 P Value 0.0001

Influence of hospital volume on Length of Stay

Hospital Class No. of Hospitals No. of Patients Length of Stay (d) Low 30 679 10.9±0.3 Moderate 9 624 10.5±0.3 High 7 1032 10.4±0.3 P Value 0.31

Influence of surgeon volume on Length of stay

Hospital Class No. of Surgeons No. of cases Length of Stay Very Low 71 71 22.7±3.2 Low 83 369 10.6±0.4 Moderate 56 1200 10.0±0.2 High 6 348 10.9±0.5 Very high 3 344 9.6±0.4 P Value <0.0001


Table 3: Multivariate analysis of risk factors for operative mortality

Variable Regression of coefficient Odds Ratio 95% CI P Value Age 0.060 1.06 1.02-1.10 0.002 Gender 0.227 1.26 0.75-2.10 0.389 Race 0.688 1.99 0.92-4.32 0.082 Medicaid 0.728 2.07 0.16-26.20 0.574 Hypertension -0.477 0.62 0.37-1.05 0.076 Diabetes 0.009 1.01 0.39-2.58 0.985 Pulmonary Disease -0.494 0.61 0.35-1.05 0.076 Smoking history -0.761 0.47 0.06-3.46 0.457 Cardiac Disease -0.039 0.96 0.56-1.65 0.887 Renal Disease 1.251 3.49 0.72-16.91 0.120 Low volume hospital 0.740 2.10 1.04-4.27 0.039 Very low volume surgeon 1.180 3.26 1.32-3.03 0.010


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Dimick (2002) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =2987 n(%)

Low High 1590 (53) 1397 (47)

Age: Mean (SD)

Low High 68 (10) 68 (10)

Hospital Number: Hn =52 Surgeon Number: Sn = NA Volume Definitions: Hospital:


Surgeon: NA End Points: Morbidity: (Complications) See Table 4: Univariate Relative Risk of several Postoperative complications at high and low volume hospitals

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: January 1994- December 1996 Outcome Measures: In hospital mortality Data Source: Maryland Uniform Data Discharge Set

Ruptured or Unruptured: Ruptured and unruptured Procedure: Resection of aneurysm

Low High 1028 (65) 812 (58)

Ruptured Aneurysm

Low High 117 (7.4) 131 (9.4)

ICD- 9 Classification: ICD-9-CM Abdominal Aorta with replacement: 3844 Aorto-iliac femoral bypass: 3925 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Mean (%)

Low High 68 (10) 68 (10)

Race:

Low High 1462 (92) 1206 (87)

Inclusion criteria: ▪ NR Exclusion criteria: ▪ Patients with injuries to

blood vessels <30 years


Dimick (2002) (Cont.) The United States of America

Morbidity: (Complications) Independent complications which are predictors of mortality

Complication OR, 95% CI, P value Pulmonary failure 1.5, 1.0-2.4; 0.05 Acute myocardial infarction 4.2, 2.0-8.4; <0.001 Shock 3.9, 1.3-11.5; =0.01 Acute renal failure 8.9, 5.7-14.1; <0.001 Septicemia 7.8, 4.5-13.6; <0.001 Surgical complications 2.7, 1.7-4.2; <0.001 Reintubation 2.9, 1.9-4.4; <0.001

Mortality: Univariate Analysis Overall mortality rate was 7.0%. Repair of ruptured Abdominal Aortic Aneurysms is 39.2% Repair of unruptured Abdominal Aortic Aneurysms is 4.7% Nature of admission is a risk factor for in-hospital mortality Nature of admission is a risk factor for in-hospital mortality

Elective 2.9 Urgent 7.0 Emergent 19.4 P P<0.001

Age >65 years has an associated mortality risk of 9.0% vs. <65 years of2.4% (P<0.001) Presence of chronic renal disease (P<0.001) Mild Liver disease (P=0.002) History of Myocardial infarction (P=0.08) Multivariate analysis High volume hospital mortality rate reduced by 37% (OR 0.63 95% CI 0.42-0.92; P=0.02).

Sex: Male

Low High 1094 (69) 936 (67)

Comorbidities: (Ramarno version of Charlson index))

Low High History of Myocardial infarction

211 (13) 149 (11)

Dementia 6 (<1) 12 (<1) COPD 173 (11) 143 (10) Malignancy 65 (4.1) 62 (4.4) Chronic Renal Disease

64 (4.0) 48 (3.5)

Mild to moderate diabetes

190 (12.0)

162 (12)

Severe diabetes mellitus

44 (2.8) 50 (3.6)

Mild liver disease

12 (<1) 9 (<1)

Other: Admission type

Low High Emergent 361 (22) 284 (20) Urgent 161 (10) 182 (132)



The following independent variables were associated with mortality, but not to the differences between High and Low Volume Hospitals

Variable OR, 95% CI; P value Age 1.1, 1.06-1.1; <0.001 Urgent Admission 2.4, 4.5-4.1; <0.001 Ruptured Aneurysm 2.8, 1.8-4.4; <0.001 Diabetes 5.4, 3.4-8.6; <0.01 Chronic Renal Disease 7.4, 4.5-12.2; <0.001

Length of stay: NR

Table 4: Univariate Relative Risk of several Postoperative complications at high and low volume hospitals

Complication High Volume % Low Volume % P Value RR, 95% CI; P value Pulmonary failure 0.3 1.2 0.007 0.45, 0.36-0.55 Reintubation (ICD 9604) 7.5 16.7 <0.001 0.53, 0.44-0.64 Pneumonia (ICD 480-487) 9.9 18.7 <0.001 0.74, 0.55-0.99 Cardiac Complications (ICD 9971) 8.2 13.0 <0.001 0.63, 0.51-0.78 Shock 4.6 6.2 <0.05 0.27, 0.10-0.75


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Dimick (2002)b The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: n(%) Pn = 13 887 LVH: 6 635 (48) HVH: 7 252 (52) Age: (Mean±SD) LVH: 72±8.1 HVH: 72±8.1 Hospital Number: Hn =

Year Total n(%) 1996 Total 507 (100) LVH 431(85) HVH 76 (15) 1997 Total 536 (100) LVH 445 (83) HVH 91 (17)


LVH <30 HVH >30

For repair of intact Abdominal Aortic Aneurysms Surgeon: NA End Points: Morbidity: NR

Level of Evidence: II Follow-up: NR Lost to Follow-up: NR Study Period: 1996-1997 Outcome Measures: In hospital mortality rate Length of stay Data Source: The Nationwide Inpatient Sample.

Ruptured or Unruptured: Ruptured and Unruptured Procedure: Resection of Abdominal Aortic Aneurysm with replacement ICD- 9 Classification: ICD-9-CM 3844 4414 4413 (rupture) Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Distribution of patients via age: n(%)

Intact AAA Age LVH HVH <50 29(<1) 24 (<1) 50-59 341 (6.3) 372 (5.8) 60-69 1 598

(29.5) 1 965 (31)

70-79 2 619 (48) 3 111 (48) >80 830 (15.3) 967 (15)

Inclusion criteria: NR Exclusion criteria: Thoracoabdominal Aneurysm with or without rupture Dissecton of theAbdominal Aorta Patients <40 with diagnosis of injury to blood vessel (ICD-9-CM: 902)



Mortality: ▪ Overall mortality was 3.8% for intact Abdominal Aortic Aneurysms ▪ There was a nine fold variation in mortality rates between men < 65 years and women

>65, 0.8&vs. 7.1% respectively ▪ Increasing age is associated with a higher in-hospital mortality rate P<0.001 ▪ Overall, patients <65 years vs. patients >65 years had a significantly low mortality rate

1.8% vs. 4.2% P<0.001 ▪ Mortality rate for patients <65 years: HVH 1.0% vs. LVH 2.7%, P=0.004 ▪ Mortality rate for patients >65 years: HVH 3.5% vs. LVH 5.2%, P<0.001 ▪ Overall, women vs. men had an increased mortality rate; 5.3% vs. 3.2%, P0.001 ▪ Other multivariate risk factors: Myocardial infarction: P<0.001 History of malignancy: P<0.001 History of Liver disease: P<0.001 Death Rates after repair for Ruptured Abdominal Aortic Aneurysm ▪ Age: >65 years, 49% vs. 32% <65 years, P<0.001 ▪ Sex: women, 57% vs. 44% men, P<0.001 ▪ Age and Sex: 60-69; women 46.1% vs. 34.2% men, P<0.001 70-79; women 56.7% vs. men 46.0%, P<0.001 Univariate risk factors for death after Ruptured Abdominal Aortic Aneurysm, ▪ Non-white: P=0.005 ▪ Chronic Obstructive Pulmonary Disease: P=0.05 ▪ Concurrent Malignancy: P=0.03 ▪ History of Myocardial infarction: P=0.02

Age: Distribution of patients via age: n(%)

Ruptured AAA <50 10 (1) 6 (1) 50-59 56 (4.5) 56 (6.3) 60-69 336 (27.0) 214 (25.5) 70-79 550 (44.1) 374 (44.5) >80 294 (23.6) 194 (23.1)

Race: n(%) Non-White LVH: 413 (7.8) HVH: 370 (6.0) (P<0.05) Sex: n(%) Female gender LVH: 1 361 (21) HVH: 1 486 (21) Comorbidities: See Table 5: Patient Comorbidity characteristics Other: Admission status: n(%)

LVH HVH Elective 3 502

(62.2) 4 478 (67.1)

Urgent 779 (13.8) 1 058 (15.8)

Emergent 1 346 (23.9)

1 146 (17.1)



Mortality: (Cont.) Multivariate analysis for Abdominal Aortic Aneurysm; Independent Risk Factors for mortality: ▪ Female: OR 1.50; 95% CI, 1.24-1.80 ▪ Age >65: OR 2.05; 95% CI, 1.59-2.64 ▪ Ruptured AAA: OR 10.8; 95% CI, 8.8-13.3 ▪ Urgent Admission: OR 1.69; 95% CI, 1.32-2.16 ▪ Emergent Admission: OR 2.78; 95% CI, 2.21-3.51 ▪ History of Myocardial infarction: OR 1.70; 95% CI, 1.22-2.37 ▪ Mild liver disease: OR 5.20; 95% CI, 2.73-9.79 Multivariate analysis for Ruptured Abdominal Aortic Aneurysm; Independent Risk Factors for mortality: ▪ Race: OR 1.60; 95% CI, 1.1-2.4 ▪ Malignancy: OR 2.76; 95% CI, 1.1-7.04 Length of stay: ▪ Overall median length of stay= 8days (IQR 6-10) for patients w intact abdominal aortic

aneurysm repair ▪ Patients >65 years had median length of stay 1 day longer than <65, (7 days [IQR, 6-

9] vs. 8 days[IQR, 6-11]) P<0.001 ▪ Other risk factors include for increased length of stay Non-White: P<0.001 Chronic Obstructive Pulmonary Disease: P<0.001 Diabetes Mellitus: P=0.03 History of Myocardial infarction: P<0.001 Chronic Renal Disease: P=0.001 Median length of stay for patients with Ruptured Abdominal Aortic Aneurysm was significantly longer (Unruptured Abdominal Aortic Aneurysm 8 days[IQR, 6-10] vs. 12 days [8-18] P<0.001)

Ruptured Aneurysm: LVH: 1219 (18.4%) HVH: 813 (11.2%) (p<0.05)


Table5: Patient Comorbidity characteristics n(%)

Patient Comorbidity LVH HVH Chronic Obstructive Pulmonary Disease* 1 656 (25) 1 577 (21.7) Diabetes Mellitus 442 (6.7) 540 (7.5) Malignancy 206 (3.1) 262 (3.6) Chronic Renal Disease 18 (<1) 27 (<1) Liver Disease 58 (<1) 70 (<1) Metastases from solid tumor 43 (<1) 44 (<1) History of myocardial infarction* 486 (7.2) 881 (12.2) * (p<0.05)


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Dimick (2003) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume Population Number: Pn = 3 912 Age: Patients treated by surgeon specialties

Surgeon Specialty Vascular 72±8 Cardiac 72±8 General 72±8

Hospital Number: Hn = 536 Surgeon Number: Sn = n(%)

Characteristic Vascular Surgeon Cardiac Surgeon General Surgeon Hospital Volume ≥35 44 (38) 83 (40) 137 (25) <35 64 (53) 111 (53) 393 (72) Operates at both 11 (9) 16 (8) 18 (3) Surgeon Volume ≥10 40 (33) 28 (13) 33 (6) <10 81 (67) 182 (87) 515 (94)


Low High <35 ≥35

Surgeon:

Low High <10 ≥10

Level of Evidence: II III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1997 Outcome Measures: In-hospital mortality Data Source: Nationwide Inpatient Sample

Ruptured or Unruptured: Unruptured Procedure: Abdominal Aortic Aneurysm repair ICD- 9 Classification: ICD-9-CM Procedure codes 3844, 3925, and Diagnostic code 4414 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:

Surgeon Specialty Vascular 72±8 Cardiac 72±8 General 72±8

Sex: female (%)

Surgeon Specialty Vascular 217 (20) Cardiac 174 (19) General 417 (22)

Inclusion criteria: Patients with ICD-9-CM code 3844, 3925, and 4414 without mention of rupture Patients with surgeon identification included in NIS data set (~60% of AAA repairs) Exclusion criteria: Patients with ICD-9-CM code 4413 (ruptured)



End Points: Morbidity: NR Mortality: ▪ Overall mortality for intact Abdominal Aortic aneurysm was 4.2%. ▪ Mortality rate differed between surgeon speciality; Vascular surgeons 2.2% had the

lowest in comparison to Cardiac 4.0% and general 5.5% (P<0.001) ▪ Surgeons who performed > 75% vs. (<75% but >50%) of vascular procedures had a

lower mortality rate 2.2% vs. 3.2% ▪ Surgeons who performed >75% vs. (<75 but >25%) of vascular procedures had a

lower mortality rate 2.2% vs. 4.1% (P<0.05) Risk adjusted analysis Repair by a general surgeon resulted in an increase in risk for surgical mortality of 76% (95% CI 10%-190%; P<0.02), compared to other surgeons. No significant difference was reported between cardiac and vascular surgeon

Independent Variable

Odds Ratio 95% CI P Value

Age >65 4.46 2.2-9.2 <0.001 Emergent Admission

3.22 2.2-4.7 <0.001

Female 1.47 1.0-2.0 0.05 General vs. Cardiac surgeon

1.76 1.1-2.9 0.02

Cardiac vs. Vascular surgeon

1.47 0.85-2.6 0.17

Race: non white

Surgeon Specialty Vascular 70 (7) Cardiac 58 (7) General 158 (8)

Comorbidities: Romano Charlson index

Vascular 1 634 2 334 ≥3 97

Cardiac 1 535 2 308 ≥3 69

General 1 1091 2 668 ≥3 176



Hospital/Surgeon volume and mortality %

Low Volume Surgeon High Volume Surgeon Low Volume Hospital 6.5 3.2 High Volume Hospital 4.2 2.4

Hospital volume/surgeon specialty and mortality %

General Cardiac Vascular Low Volume Hospital

6.3 5.9 2.7

High Volume Hospital

4.4 2.5 1.9

Surgeon volume/surgeon specialty and mortality %

General Cardiac Vascular Low Volume Surgeon

6.5 5.0 2.5

High Volume Surgeon

3.2 2.5 2.0

Length of stay: NR


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Dimick (2003)b The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =11,863

Low Volume High Volume Patients, N 6 357 5 506

Age: Mean±SD

Low Volume High Volume 72±8 72±8

Hospital Number: Hn = NR Surgeon Number: Sn = NR Volume Definitions: Hospital:

Low Volume High Volume <30 >30

Surgeon: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1996-1997 Outcome Measures: Complications Data Source: Nationwide In-patient Sample

Ruptured or Unruptured: NR. Although ICD code for intact AAA used Procedure: Abdominal Aortic Aneurysm Repair ICD- 9 Classification: ICD-9-CM Procedure code 3844 Diagnostic code 4414 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:


Race: Non-white n(%):

Low Volume High Volume 328 (8) 305 (6)

Sex: Female n(%):

Low Volume High Volume 1 132 (21) 1 313 (21)



Dimick (2003)b (Cont.) The United States of America

End Points: Morbidity: Abdominal aortic Aneurysm patients with one complication had a 10.4% increase in the risk of mortality than patients with no complications 2.9% (OR 4.0; 95% CI, 3.3-4.9; P<0.001) Overall rate of complication 13% range (9-18, P<0.001) Mortality:

Risk of Mortality after complications Complication Abdominal Aortic Aneurysm OR (95% CI)

Aspiration 2.5 (1.8-3.4) Cardiac complications 3.9 (2.9-5.4) Postoperative infection 2.5 (0.9-6.9)

Pneumonia 2.7 (1.6-4.5) Pulmonary failure 5.3(4.0-7.1)

Renal failure 10.4 (7.7-14) Septicemia 20.7 (13-34)

Surgical Complications 2.4(1.8-3.3) Length of stay: NR

Comorbidities: Charlson Comorbidity n(%):

Charlson Score

Low Volume

High Volume

0 2 919 (53) 3 351 (53) 1 2 004 (36) 2 255 (36) 2 483 (9) 627 (10) ≥3 100 (2) 124 (2)

Type of Admission n(%)

Low Volume

High Volume

Urgent Admission

643 (14) 1 570 (15)

Emergent Admission

513 (11) 1 095 (10)


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Dimick (2004) The United States of America Patients included in this study are likely to be a cohort originally reported in Dimick (2002)

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =2987 Age: Total years n(%)

<65 2067 (69) >65 920 (31)

Mean (SD)

<65 56 (7) >65 73 (3.5)

Hospital Number: Hn = 52 Acute care hospitals Surgeon Number: Sn = NA Volume Definitions: Hospital:


Surgeon: NA End Points: Morbidity: NR Mortality: Overall mortality was 7.0% Mortality for patients < 65 years was 2.5% Mortality for patients > 65 years was 9.4%

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 01/1994 – 12-1996 Outcome Measures: In-hospital mortality Hospital length of stay Data Source: Uniform Data discharge Set, maintained by the Health Services Cost Review Commission of Maryland

Ruptured or Unruptured: Ruptured and Unruptured Procedure: Resection of Abdominal Aorta with replacement Resection of Abdominal Aorta with aortoiliac/femoral bypass ICD- 9 Classification: ICD-9-CM Resection of Abdominal Aorta with replacement: 3844 Resection of Abdominal Aorta with aortoiliac/femoral bypass 3925 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Total years n(%)

<65 2067 >65 920

Mean (SD)

<65 56 (7) >65 73 (3.5)

Inclusion criteria: NR Exclusion criteria: Patients with injury to blood vessel (ICD-9-CM 902)


Dimick (2004) (Cont.) The United States of America Patients included in this study are likely to be a cohort originally reported in Dimick (2002)

Mortality:

< 65 Years >65 Years Low Volume 2.7 11.9 Medium Volume 2.1 9.9 High Volume 2.7 6.9 P Value 0.8 0.005

Univariate and Multivariate Predictors of in-hospital mortality: < 65 Years

Univariate Multivariate (95% CI)

P value

Age 0.03 1.1 (0.9-1.2) 0.2 Aortic aneurysm resection

<0.001 0.3 (0.1- 1.1) 0.06

Emergent admission

<0.001 4.2 (1.2-14.0) 0.02

Mild Liver disease 0.06 9.6 (0.9-100) 0.06 Chronic renal disease

<0.001 7.7 (2.3-26.0) 0.001

Ruptured aortic aneurysm

<0.001 2.7 (0.7-10.4) 0.1

High hospital volume

0.7 1.3 (0.4-4.3) 0.7

Race:

<65 777 (85) >65 1867 (90)

Sex:

<65 622 (68) >65 1408 (68)

Comorbidities: n(%)

<65 >65 Myocardial infarction

108 (12) 252 (12)

Dementia 1 (0.1) 17 (1) COPD 77 (8) 239 (12) Malignancy 11 (1) 116 (6) Chronic Renal Disease

31 (3) 81 (4)

Mild to moderate Diabetes Mellitus

119 (13) 233 (11)

Severe Diabetes Mellitus

48 (5) 46 (2)

Mild Liver Disease

8 (1) 13 (1)

Metastases from solid tumor

2 (0.2) 17 (1)


Dimick (2004) (Cont.) The United States of America Patients included in this study are likely to be a cohort originally reported in Dimick (2002)

Univariate and Multivariate Predictors of in-hospital mortality: > 65 Years

Univariate Multivariate (95% CI)

P value

Age 0.001 1.1 (1.0-1.2) <0.001 Aortic aneurysm resection

0.01 1.0 (0.6-1.5) 0.8

Emergent admission

<0.001 2.5 (1.5-4.0) <0.001

Mild Liver disease 0.006 3.7 (0.9-15.0) 0.07 Chronic renal; disease

<0.001 7.4 (4.2-13.0) <0.001

Ruptured aortic aneurysm

<0.001 6.0 (3.7-9.9) <0.001

High hospital volume

0.005 0.57 (0.37-0.86) 0.008

Length of stay: Median length of stay for all patients was 8 days (range 6-12 IQR) There was a small statistical difference in length of stay between patients older than and younger than 65 years. (8 days vs.7; p,0.001) Multivariate predictors of increased length of stay for patients >65 years included:

Age <0.001 Non-white <0.001 Female gender =0.03 Urgent admission <0.001 Emergent admission <0.001

Multivariate predictors for patients <65 years include:

Female gender =0.03 Urgent admission <0.001 Emergent admission <0.001

Severity of illness: Admission type <65 Years

Elective NR Urgent 114(12) Emergent 160 (17)

>65 Years

Elective NR Urgent 229 (11) Emergent 485 (23)

Extent of procedure <65 Years

AAA repair 338 (37) Aortoiliac bypass 582 (63)

>65 Years

AAA repair 1502 (73) Aortoiliac bypass 565 (27)

Ruptured

<65 40 (4) >65 208 (10)


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Forbes (2005) Canada

Hospital Volume and/or Surgeon Volume: Hospital Volume (Beds) Population Number: Pn =n (%)

Total Open EVAR 1996 1818 (91.1) 178 (8.9)

Age: n(range)

Total Open EVAR 72.1 (71.7-73.1) 71.9 (71.1-72.9) 73.7 (72-81.8)

Hospital Number: Hn = Surgeon Number: Sn = NA Volume Definitions: Hospital: (Beds)

Low Medium High <199 200-399 >400

Surgeon: NA End Points: Morbidity: NR Mortality:

Beds Procedure n Mortality n (%) <199 Open 58 4 (6.9) 200-399 Open 395 16 (4.0) >400 Open 350 13 (3.7)

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 01/04/2003 – 31/03/1994 financial year Outcome Measures: Mortality Length of stay Data Source: Canadian Institute for Health Information Database

Ruptured or Unruptured: Unruptured Procedure: Non-urgent open and endovascular Abdominal Aortic Aneurysm repair ICD- 10 Classification: ICD-10-CA Code NR Training Hospital: Number of hospitals NR, but examined in relation to hospital volume and procedure type, see Table 6: Elective Abdominal Aortic Aneurysm in Academic hospitals by procedure Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: NR Race: NR Comorbidities: NR

Inclusion criteria: NR Exclusion criteria: Ruptured Aneurysms (ICD-10 diagnosis code; 171.3)


Forbes (2005) (Cont.) Canada

Length of stay:

Beds Procedure n Length of stay days

<199 Open 58 12.9 200-399 Open & EVAR 395 10.6 >400 Open & EVAR 350 11.3

Table 6: Elective Abdominal Aortic Aneurysm in Academic hospitals by procedure

Beds Procedure n Length of stay days

Mortality n (%)

Academic Open 1015 12.7 51 (5.0) EVAR 171 6.1 1 (0.6) Total 1186 11.9 50 (4.4)


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Goodney (2003) The United States of America It is likely that the patient cohort used in this study contains individuals from Birkmeyer (2002)

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =

VLVH VHVH Low Risk 19 674 20 782 High Risk 7 853 6 467

Age: >75 years %

VLVH VHVH Low Risk 28.2 28.5 High Risk 83.0 84.5

Hospital Number: Hn = NR Surgeon Number: Sn = NA Volume Definitions: Hospital:

Patients VLVH VHVH Low Risk <17 >79 High Risk <17 >79


Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1994 to 1999 Outcome Measures: Operative mortality (Death in-hospital, or before 30 days after AAA) Data Source: Medicare Database (MEDPAR)

Ruptured or Unruptured: Unruptured Procedure: Abdominal Aortic Aneurysm repair ICD- 9 Classification: ICD-9- NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: 65-69 70-74 75-79 80-84 85-99 Race: Black %


Sex: Female %


Inclusion criteria: NR Exclusion criteria: Diagnosis suggesting rupture or a Thoracoabdominal aneurysm. Patients <65 and >99 were also excluded


Goodney (2003) The United States of America It is likely that the patient cohort used in this study contains individuals from Birkmeyer (2002)

Mortality: Relative risk of mortality for Low and High risk patients % and relative risk (95%CI)

Patients VLVH VHVH RR (95%CI) Low Risk 5.6 3.3 0.51 (0.49-0.53) High Risk 12.4 7.4 0.54 (0.52-0.56)

Predicted Mortality


Length of stay: NR

Comorbidities: Charlson Score >2 %


Admission Status: Urgent/ Emergent %



Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Huber (2001) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =16 450 Age: 71.6±7.4 Hospital Number: Hn =

Small Medium Large 1 117 (6.8) 4 247 (25.9) 11 039 (67.3)

Surgeon Number: Sn =NA Volume Definitions: Hospital: NR Surgeon: NA End Points: Morbidity:

Non-teaching 31.3 % Teaching 34.6 % P value <0.0001 Rural 36.9 % Urban 32.0 % P value <0.001 Small 33.7 % Medium 33.6 % Large 31.8% P value 0.074

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1994-1996 Outcome Measures: Morbidity Mortality Length of stay Data Source: National Inpatient Sample

Ruptured or Unruptured: Unruptured Procedure: Elective repair of abdominal aortic aneurysm (Resection and replacement) ICD- 9 Classification: Diagnosis code: 441.4 Procedure code: 38.44 Training Hospital: Teaching: 5 513 (33.3) Non-teaching: 10 937 (66.7) Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: n(%)

50-59 960 (5.8) 60-69 5 228 (31.8) 70-79 7 965 (48.4) >79 2 295 (14.0)

Race: n(%) White: 13 009 (94.7) Black: 286 (2.1) Other race: 450 (3.3) Sex: Male: 13 114 (79.7) Female: 3 340 (20.3)

Inclusion criteria: Patients were included if they had the diagnostic code 441.4 and the procedure code 38.44 Exclusion criteria: Patients younger than 50. Secondary diagnosis of ruptured AAA, (441.3-441.5). Aortic dissection (441.0) Thoracic/ Thoracoabdominal aortic aneurysm (441.1,441.2, 441.6, 441.7) coarctation of the aorta (747.1), Marfan syndrome and other congenital anomalies (759.8), gonadal dysgenesis-Turner’s syndrome (758.6), and poly arteritis nodosa (446.0)


Huber (2001) (Cont.) Canada

Morbidity: Overall complication rate 32.4% Mortality:

Group Mortality Rate Non-teaching 4.2 % Teaching 4.1 % P value 0.54 Rural 4.0 % Urban 4.2 % P value 0.69 Small 4.9 % Medium 4.4 % Large 4.0 % P value 0.11

Overall In hospital death 4.2% Length of stay:

Group Length of Stay (days) Non-teaching 9.7±7.0 Teaching 10.7±10.0 P value 0.0001 Rural 9.9±7.5 Urban 10.0±8.2 P value 0.5 Small 10.3±7.7 Medium 10.1±8.6 Large 10.0±8.0 P value 0.27

Mean Length of Stay 10.0±8.1 days. Median Length of Stay 8 days.

Comorbidities:

Comorbidity ICD-9 Diabetes mellitus 250.0-250.9 Hypertension 401.1-405.9 Preoperative renal insufficiency

584.0-586.0, 403.0-403.9

Chronic Obstructive Pulmonary disease

490.0-496.0

Ischemic heart disease

410.0-414.9

Cerebral Vascular occlusive disease

430.0-438.0

Peripheral occlusive arterial disease

440.0-440.9, 443.0-443.9

Other: Hospital characteristics: Urban: 15 178 (92.5) Rural: 1 273 (7.5)


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Manheim (1998) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = Unruptured 35 130 Ruptured 7327 Age: See Table 7: Means for Ruptured and Unruptured Abdominal Aortic Aneurysm Hospital Number: Hn = NR Surgeon Number: Sn =NA Volume Definitions: Hospital:


The percentage of procedures performed in low volume hospitals decreased from 60.0% in 1982, to 49.1% in 1994. However the percentage of procedures performed in High Volume Hospitals remained relatively constant over the same period 9.4% in 1983, and 9.3 in1994. These difference are accounted for by the increase in hospitals performing this procedure Surgeon: NA End Points: Morbidity: NR

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1982-1994 Outcome Measures: Mortality Data Source: California Discharge data compiled by the Office of Statewide Health, Planning and Development (OSHPD)

Ruptured or Unruptured: Ruptured and Unruptured Procedure: Abdominal Aortic Aneurysm Repair ICD- 9- Classification: 38.34, 38.44, 38.64 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: See Table >>>:Means for Ruptured and Unruptured Abdominal Aortic Aneurysm Race: NR Sex: See Table 7: Means for Ruptured and Unruptured Abdominal Aortic Aneurysm Comorbidities: See Table 7: Means for Ruptured and Unruptured Abdominal Aortic Aneurysm



Manheim (1998) (Cont.) The United States of America

Mortality: Admissions through emergency have an increased rate of mortality of 4.6%, than if the patient was admitted electively. Mortality odds in 1994 decreased to 41.5% of those reported in 1982 for Unruptured Abdominal Aortic Aneurysm. Ruptured Overall mortality for ruptured Abdominal Aortic Aneurysms was 47.9%. See Table 8: Logistic regression for variables of in hospital mortality for Ruptured and Unruptured Abdominal Aortic Aneurysm Unruptured Overall mortality for Unruptured Abdominal Aortic Aneurysm was 7.56% Operative mortality for patients treated over this period decreased (P<0.01) Hospitals performing 20-49 and>50 Unruptured Abdominal Aortic Aneurysm operations per year had mortality odds of 77.6% and 83.8% of those experienced by hospitals performing <20 operations per year. Length of stay: NR

Type of admission: See Table 7: Means for Ruptured and Unruptured Abdominal Aortic Aneurysm


See Table 7: Means for Ruptured and Unruptured Abdominal Aortic Aneurysm

Variable Unruptured Abdominal Aortic Aneurysm Ruptured Abdominal Aortic Aneurysm Patients died in hospital 0.0756 (0.2643) 0.4788 (0.4996) Patient’s age 45-54 0.0266 (0.1610) 0.0162 (0.1264) Patient’s age 55 64 0.1684 (0.3742) 0.1524 (0.3595) Patient’s age 65-74 0.4437 (0.4968) 0.4103 (0.4919) Patient’s age75-84 0.2646 (0.4412) 0.3326 (0.4712) Patient’s age >85 0.0322 (0.1766) 0.0869 (0.2818) Male Patient 0.7901 (0.4072) 0.8313 (0.3745) Admitted through emergency 0.1045(0.3059) 0.6674 (0.4712) Hospital Volume 20-49 0.4123 (0.4923) 0.3105 (0.4627) Hospital Volume 50-99 0.0951 (0.2934) 0.0465 (0.2107) n 35 130 7 327

Table 8: Logistic regression for variables of in hospital mortality for Ruptured and Unruptured Abdominal Aortic Aneurysm

Variable Unruptured Abdominal Aortic Aneurysm Ruptured Abdominal Aortic Aneurysm Intercept P<0.001 P<0.001 Patient’s age 45-54 0.99 P=0.959 0.78 P=0.727 Patient’s age 55 64 1.14 P=0.257 1.17 P=0.816 Patient’s age 65-74 1.75 P<0.001 1.99 P=0.318 Patient’s age 75-84 2.79 P<0.001 3.02 P<0.109 Patient’s age >85 4.55 P<0.001 4.48 P=0.031 Male Patient 0.68 P<0.001 0.74P<0.001 Admitted through emergency 4.55 P<0.001 1.68 P<0.001 n 35 130 7 327


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Pronovost (1999) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume Population Number: Pn =2 606 Age: Mean (SD 68 (10) Hospital Number: % Hn =

Low High 84 16

Surgeon Number:% Sn =

Low High 39 61


Low High <36 >36

Surgeon:

Low High <8 >8

End Points: Morbidity: NR

Level of Evidence: III-2 Follow-up: NR Lost to Follow-up: NR Study Period: January 1994 and December 1996 Outcome Measures: In-hospital mortality Hospital length of stay ICU days Data Source: Non confidential patient data from the Uniform Health Discharge Data Set maintained by the Maryland Health Services Review Commission. ICU Organizational Questionnaire

Ruptured or Unruptured: Ruptured and Unruptured Procedure: Resection for Abdominal Aorta with replacement Aorto-iliac-femoral bypass ICD- 9 Classification: ICD-9-CM 3844 3925 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: 68 (10) Race: White % 89 Sex: Male % 68 Comorbidities: See Table 9: Patient comorbidities

Inclusion criteria: All patients aged over 30 years and discharged from a Maryland hospital between January 1994 and December 1996. Patients with a principle diagnosis code of 3844 or 3925 Exclusion criteria: Patients less than 30 years old Patients with ICD-9-Cm codes of 902 Note: We have not included data reported on non-responding hospitals


Pronovost (1999) (Cont.) The United States of America

Mortality: Overall in-hospital mortality rate: mean=7.3, SD=3.8 Complications independently associated with Mortality:

Complication Odds Ratio Acute myocardial infarction 10.6 95% CI, 5.1-21.9 Cardiac Arrest 91.0 95% CI, 35.0-397.0 Acute Renal Failure 8.3 95% CI, 3.9-17.8 Septicemia 7.9 95% CI, 4.3-14.6 Platelet transfusion 4.5 95% CI, 1.6-12.7 Reintubation 3.1 95% CI, 2.2-4.3 Re-operation for bleeding 2.5 95% CI, 1.3-4.9 Surgical complications after operation* 3.7 95% CI, 2.2-6.0

*Haemorrhage, Laceration, Disruption of wound Adjusted in-hospital mortality Odds Ratio (95% CI): 1.7 (1.3-2.3) Length of stay: Overall Length of Stay, median=8, range=0-171 (Days) Overall stay in intensive care unit, median=2, range=0-37 Bivariate factors influencing length of stay: Not having a fulltime ICU medical director: (10%, 95% CI, 4%-16%) Having a nurse patient ratio of less than 1:2 during the evening (17%, 95% CI, 1%-35%) Not having a monthly review of ICU morbidity and mortality: (18%, 95% CI, 8%-40%) Adjusted estimate increase in Length of Stay (95% CI): 6 (-3-15) Adjusted estimate increase in ICU days (95% CI): -22 (-43-0)

Type of admission:

Elective 67 Urgent 13 Emergent 20


Table 9: Patient comorbidities

Patient Characteristic % Previous Myocardial infarction 12 Mild Diabetes mellitus 12 Chronic Obstructive Lung Disease 10 Any Malignancy 4 Chronic Renal Disease 4 Severe Diabetes mellitus 3 Mild Liver Disease 1 Dementia 1 Metastatic Solid Tumour 0 Severe Liver Disease 0 Defined in accordance with the Charlson Romano Index


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Sollano (1999) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 9847 Age: NR Hospital Number: Hn = 195 Surgeon Number: Sn =NA Volume Definitions: Hospital: Numerical volume definitions were not reported. However the author reported that each volume had an equivalent number of patients, at least 6 deaths and equal intervals between each group. Surgeon: NA End Points: Morbidity: NR Mortality: Overall mortality equals 5.5% over the study duration (6 years) Lowest volume hospital volume category averaged 2 cases per year with a mortality rate of 13%

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1990-1995 Outcome Measures: Mortality Data Source: Statewide Planning and Research Cooperative Systems (SPARCS)

Rupture or Unruptured: Unruptured Procedure: Elective Abdominal Aortic Aneurysm Repair ICD- 9 Classification: ICD-9-CM Abdominal Aortic Aneurysm 38.44 Primary or Secondary procedure code of 44.14 (AAA without mention of rupture) Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Adjusted not reported Race: NR Sex: Adjusted not reported Comorbidities: NR

Inclusion criteria: Patients undergoing Elective Abdominal Aortic Aneurysm Repair (ICD-9-CM) 38.44, with Primary or Secondary procedure code of 44.14 (AAA without mention of rupture) Exclusion criteria: Patients undergoing treatment for ruptured Abdominal Aortic Aneurysms


Sollano (1999) The United States of America

Mortality: Cont. Highest volume hospital volume category averaged 27 cases per year with a mortality rate of less than 2%

Coefficient P value OR 95 % CI Volume/100 -0.2459 0.001 0.782 0.722-0.847

Age, and female sex were significant predictors of death for elective Abdominal Aortic aneurysm repair.

Coefficient P value OR 95 % CI Age 0.0783 0.001 1.081 1.068-1.095

Coefficient P value OR 95 % CI Female 0.2224 0.02 1.249 1.029-1.517

Length of stay: NR


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Trivedi (2006) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =21 287 Age: Mean 72.1 Hospital Number: Hn = NR Surgeon Number: Sn =NA Volume Definitions: Hospital: Reported as quartiles

Low Medium High Very High Quartile 0-25 26-50 21-75 76-100 Volume <4 4-9 10-20 >20


Procedure White Mortality Rate %

Black Mortality Rate %

P Value Hispanic Mortality Rate %

P Value

Elective AAA repair

4.0 7.8 0.01 5.3 0.39

Non-elective AAA repair

21.1 21.1 0.97 22.7 0.53

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1998 - 2001 Outcome Measures: Volume Hospital use per racial minority Mortality Data Source: Nationwide Inpatient Sample (NIS)

Rupture or Unruptured: NR Procedure: AAA repair or resection ICD- 9 Classification: ICD-9-CM Diagnosis: 441.3, 441.4 Procedure:38.34, 38.44, 38.64 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: <65 65-79 >79 Race:

White 91 Black 4 Hispanic 2 Other 3

Sex: Male % 78 Comorbidities: Mean number of comorbidities: 1.83

Inclusion criteria: NR Exclusion criteria: All hospitalizations with an ICD-9-CM diagnosis code of 14, Major diagnosis code 15 Age <40 years


Trivedi (2006) (Cont.) The United States of America

Mortality:

Procedure Adjusted Odds Ratio (Model 1)

Adjusted Odds Ration (Model 2)

Elective Abdominal Aortic Aneurysm Repair White REF REF Black 2.19 (1.37-3.52) 2.13 (1.32-3.42) Hispanic 1.35 (0.67-2.71) 1.30 (0.65-2.62) Non-elective Abdominal Aortic Aneurysm Repair White REF REF Black 0.94 (0.71-1.24) 0.90 (0.67-1.19) Hispanic 1.16 (0.87-1.55) 1.06 (0.80-1.42)

Model 1: Controlled for: Age, Race, Gender, Comorbidity, presence of chronic disease, urgency of admission, and presence of Myocardial infarction as a principle diagnosis Model 2: All covariates from Model 1, plus hospital volume Length of stay: NR

Other: Insurance Type: %

Medicare 76 Medicaid 2 Private 20 Self Pay 1 Other 2

Median income: %

<25 000 4 25 000-34 999 31 35 000-44 999 29 >45 000 35

Admission type: %

Elective 59 Non-elective 41

Hospital Location: %

Urban 94 Rural 6

Hospital Region: %

Northeast 25 Northwest 12 South 48 West 15


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Tu (2001)) Canada

Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume (Only surgeon Volume mortality rates were reported) Population Number: Pn = 5878 Surgeon

Vascular General Cardiac 4415 1193 270

Age: NR Hospital Number: Hn = Surgeon Number: Sn =

Vascular General Cardiac 63 53 14


Small Medium Large 1-6 7-15 >15

Surgeon:

Small Medium Large <5 5-13 >13


Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 01/04/1992-31/03/1996 Outcome Measures: 30-day mortality Data Source: Ontario Health Insurance Plan (OHIP), Canadian Institute for Health Information (CIHI), and Ontario Registered Persons Database

Ruptured or Unruptured: Unruptured Procedure: Elective Abdominal Aortic Aneurysm surgery ICD- Xx Classification: NA Physician billing codes: R802 R816 R817 Training Hospital: Hn=43 Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: 65-74 >75 Race: NR Sex: Not reported by hospital volume or as a mean. Comorbidities: Charlson Comorbidity score

Inclusion criteria: Patients enrolled with physician billing codes R802, R816, R817 Exclusion criteria: Ruptured Abdominal Aortic Aneurysm


Tu (2001)) (Cont.) Canada

Mortality: Hospital:

Annual surgeon AAA Volume



Small 0.6064 1.83 1.01-3.32 0.0452 Medium 0.3333 1.40 0.97-2.02 0.0755 Large 1.00

Surgeon:

Annual Hospital AAA Volume



Small, Medium

-0.12 0.89 0.56-1.41 0.6133

Large -0.0182 0.98 0.73-1.33 0.9055 Teaching 1.00

Patient;

Patient Regression coefficient


Age 65-74 0.4804 1.62 1.05-2.49 0.0289 >75 1.0870 2.97 1.93-4.57 <0.0001 Male -0.1123 0.89 0.65-1.24 0.4968 Transferred Status

0.9717 2.64 1.42-4.93 0.0021

Charlson Comorbidity score

0.3342 1.40 1.27-1.54 <0.0001


Tu (2001)) (Cont.) Canada

Specialty:



General 0.4838 1.62 1.18-2.23 0.0030 Cardiac -0.0731 0.93 0.45-1.91 0.8423 Vascular 1.00

Mortality: (Cont.) Specialty:

Crude 30 day mortality Risk Adjusted 30 day mortality (95% CI)

Vascular 3.6 4.0 (1.4-6.6) General 6.5 6.2 (5.1-7.3) Cardiac 3.3 3.5 (2.9-4.1)

Length of stay: NR


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Urbach (2003) Canada

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 6 279

Low Medium High Very High Quartile 0-24 25-49 50-74 >75 Number 1679 1580 1902 1118

Age: Mean (SD)

Low Medium High Very High Quartile 0-24 25-49 50-74 >75 Age 70.5 (7.2) 70.6 (7.3) 71.0 (7.5) 70.7 (7.5)

Hospital Number: Hn = 57

Low Medium High Very High Quartile 0-24 25-49 50-74 >75 Number 39 10 6 2

Surgeon Number: Sn =NA Volume Definitions: Hospital:

Low Medium High Very High Quartile 0-24 25-49 50-74 >75

Volume was analysed in quartiles, the “Very High” definition was provided as patients in the 75% and above quartile, definitions for the remaining three quartiles were then estimated by the review author. Surgeon: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 01/04/1994 – 03/31/1999 Outcome Measures: Operative death (up to 30 days post procedure) Data Source: Canadian Institute of Health Information, and the Ontario Registered Persons Database

Rupture or Unruptured: Unruptured Procedure: Repair of Unruptured abdominal Aortic Aneurysm ICD- 9 Classification: Diagnosis:441.4, 441.9 Canadian Classification of Diagnostic Therapeutic and Surgical Procedures (CCP): 50.24, 50.34, 50.54, 51.25 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:

Low 70.5 (7.2 Medium 70.6 (7.3) High 71.0 (7.5) Very High 70.7 (7.5)

Race: NR



Urbach (2003) (Cont.) Canada

End Points: Morbidity: NR Mortality: Overall risk of operative death (within 30 days) was 4.2%

Low Medium High Very High P value Number of Patients

1679 1580 1902 1118

Number of deaths

81 85 63 36

Risk of death (%)

4.8 5.4 3.3 3.2 <0.01

Adjusted Relative Risk of death (95% CI)

1.5 (1.0-2.2)

1.8 (1.2-2.8)

1.0 (0.7-1.5)

1.0 <0.01

Potentially avoidable deaths:

Number of Patients

Number of deaths

Risk of death (%)

Point estimate (95% CI)

% of all deaths (95% CI)

Repair of Unruptured Abdominal Aortic Aneurysm

6 279 265 4.2 14 (1-25)

26.4 (1.9-47.2)

Length of stay: NR

Sex: Male %

Low 82.9 Medium 81.0 High 82.4 Very High 83.3

Comorbidities: Mean Charlson Comorbidity Score (SD)

Low 0.6 (0.9) Medium 0.5 (0.8) High 0.5 (0.9) Very High 0.5 (0.9)

Appendix C 1.2: Volume outcome tables – Abdominal Aortic Aneurysm Authors Volume outcome data

Birkmeyer (2002) The United States of America

When observed as a continuous variable hospital volume was related to both observed and adjusted mortality (P<0.001)

Authors Volume outcome data


Surgeon Volume Adjusted for surgeon, Odds Ratio for operative death, (95% CI); 1.65 (1.46-1.86). Adjusted for hospital, Odds Ratio for operative death, (95% CI); 1.55 (1.36-1.77). Proportion of effect of Surgeon Volume attributable to Hospital Volume: 15% Surgeon volume was inversely related to mortality for Un ruptured Abdominal Aortic aneurysms p= 0.001 Hospital Volume Adjusted for hospital, Odds Ratio for operative death, Hospital Volume (95% CI); 1.40 (1.23-1.59) Adjusted for Hospital, Odds Ratio for operative death, Surgeon Volume(95% CI); 1.17 (1.02-1.35) Proportion of effect of Hospital Volume attributable to Surgeon Volume: 57% When observed as a continuous variable hospital volume was related to mortality (P<0.001). After afjustment for surgeon volume, hospital volume remained a significant determining factor of decreased mortality.



There is a statistically significant difference between in-hospital mortality rates for low and high volume hospitals (p<0.05)

Appendix C 1.2: Volume outcome tables – Abdominal Aortic Aneurysm (continued)



This study did not report a statistical analysis of the relationship between low and high volume hospitals categorised as <11.8 (very low) 11.8-21.5 (low), 21.6-35.0(medium), 35.1-57.3 (high), and >57.3 (very high)


Dardik (1998) The United States of America

Mortality rate decreased with increased surgeon volume low (50.8±5.8), medium (47±4.6), high (36.3±5.1) p=0.05. Length of stay decreased with increased surgeon volume low (11.7±0.8), medium (11.6±1.0), high (12.4±1.8) p=0.46. Mortality rates did not differ significantly between hospital volume categories for either ruptured abdominal aortic aneurysms low (45.6±4.1), medium (49.2±3.6), high (47.1±3.6) p=0.80; or un ruptured abdominal aortic aneurysms low (54.0±6.3), medium (46.0±3.6), high (46.9±3.0) p=0.53 Length of stay rates did not differ significantly between hospital volume categories based on ruptured abdominal aortic aneurysms rates, low (14.0±1.3), medium (10.4±1.0), high (11.6±0.9) p=0.15 Although mean length of stay was longer and hospital charges were higher at low volume hospitals in comparison to medium- to high-volume hospitals, these differences were not significant. Patients treated for Ruptured Abdominal Aortic Aneurysm by high volume surgeons experienced comparable Length of Stay, but significantly lower hospital charges compared with patients receiving treatment by medium- and low- volume surgeons.

Appendix C 1.2: Volume outcome tables – Abdominal Aortic Aneurysm (continued) Authors Volume outcome data


The operative mortality rate was highest amongst surgeons from low volume hospitals, P=0.0106

Variable Regression of coefficient Odds Ratio 95% CI P Value Low Volume Hospital 0.740 2.10 1.04-4.27 0.039 Very Low Volume Surgeon 1.180 3.26 1.32-8.03 0.010

Mortality rates did not differ significantly between hospital volume categories for abdominal aortic aneurysms, low (4.3±0.8), medium (4.2±0.8), high (2.5±0.5) p=0.08 Length of stay rates did not differ significantly between hospital volume categories for abdominal aortic aneurysms, low (10.9±0.3), medium (10.5±0.3), high (10.4±0.3) p=0.31 Mortality rate decreased with increased surgeon volume very low (9.9±3.6), low (4.9±1.1), medium (2.8±0.5), high (2.9±0.9), very high volume (3.8±1.0) p=0.0106. Length of stay decreased with increased surgeon volume very low (22.7±3.2), low (10.6±0.4), medium (10.0±0.2), high (10.9±0.5), very high volume (9.6±0.4) p<0.0001


Dimick (2002) The United States of America

When volume was considered dichotomously (<36 or >36 per year) High Volume Hospitals were found to have a decreased mortality rate compared to Low Volume Hospitals (5.6% vs. 8.0%, P=0.005). When volume was considered over three categories, High Volume Hospitals (5.6%) had a lower mortality rate compared to both Medium Volume (6.8%) and Low Volume (8.7%), (p=0.03) When complications were entered into a secondary multivariate analysis, hospital volume no longer remained a significant predictor of mortality


Dimick (2002)b The United States of America

High Volume Hospitals had a lower death rate than low volume hospitals for unruptured AAA(3.1% vs. 4.7%; P<0.001), equalling an unadjusted RR of 1.54 (95% CI, 1.28-1.85) for patients receiving treatment in Low Volume Hospitals. In a multivariate analysis adjusting for case mix AAA surgery at a Low Volume Hospital was associated with a 56% increase in the surgical death rate (OR 1.56, 95% CI, 1.33-1.82) In a second a multivariate analysis Low Volume Hospitals were a significant predictor of mortality for intact AAA (OR 1.71, 95% CI, 1.37-2.14), and ruptured AAA (OR 1.43, 95% CI, 1.15-1.78) High volume hospitals had a lower mortality rate than low volume hospitals (43% vs. 49%, p=0.001). High Volume Hospitals had a 1 day shorter Length of Stay than Low Volume Hospitals (7 days [IQR, 6-10] vs. 8 days [IQR, 6-10]; P= 0.002) There was no statistically significant difference in Length of Stay for ruptured AAA. There was no statistical significance in the Multivariate analysis for Length of Stay for ruptured AAA. Un-adjusted In-hospital mortality rates %

Low Volume Hospitals High Volume Hospitals Intact Abdominal Aortic Aneurysm Overall 4.7 3.1 Age <65 years Overall 2.7 1.0 Men 2.5 0.8 Women 3.9 1.9 Age <65 years Overall 5.2 3.5 Men 4.6 3.2 Women 7.1 4.4 Ruptured Abdominal Aortic Aneurysm Overall 49.6 42.4 Age <65 years Overall 32.4 32.4 Men 29.1 30.6 Women 61.1 50.0 Age <65 years Overall 52.4 44.3 Men 50.8 41.5 Women 58.2 55.2



Patients undergoing repair at High Volume Hospitals had a 30% reduction in risk of mortality (95% CI, 2%-51%; P<0.05) High Volume Hospitals had a lower mortality rate vs. Low volume hospitals, 3.0% vs. 5.5% (P<0.001) Mortality rates for Abdominal Aortic Aneurysm repair for High Volume Surgeons vs. Low Volume Surgeons was 2.5% vs.5.6% (P<0.001) Surgery by a High Volume Surgeon was associated with a 40% reduction in mortality (95% CI, 12%-60%; P=0.01) High volume surgeons are associated with lower mortality rates than low volume surgeons at either high volume hospitals or low volume hospitals.

Independent Variable


High Volume Hospital

0.70 0.49-0.98 <0.5

High Volume Surgeon

0.60 0.40-0.88 0.01


Dimick (2003)b The United States of America

Risk of post-operative complications at Low Volume Hospitals for Abdominal Aortic Aneurysm Repair

Complication Rate at High Volume Hospitals %) Rate at Low Volume Hospitals % Adjusted Odds Ratio (95% CI)

Adjusted P value

1≥ complications 11.7 15.3 0.67 (0.59-7.6) <0.001 Aspiration 3.6 5.7 0.57 (0.47-0.70) <0.001 Cardiac Complication 3.1 3.8 0.79 (0.63-0.99) 0.05 Post operative infection 0.4 0.4 0.96 (0.49-2.0) 0.9 Pneumonia 2.0 1.0 0.46 (0.31-0.64) <0.001 Pulmonary failure 3.1 3.5 0.78 (0.62-0.99) 0.04 Renal Failure 1.8 2.2 0.63 (0.46-0.85) 0.003 Septicemia 0.5 0.6 0.72 (0.41-1.26) 0.3 Surgical Complications 2.0 2.9 0.62 (0.47-0.82) 0.001



In a multivariate analyses, adjusting for case-mix high volume hospital volume was associated with decreased mortality for patients older than 65 years (OR 0.57; 95% CI 0.37-0.86; p=0.008) There was no association of hospital volume with length of stay in univariate analysis. Patients >65 years old had in hospital mortality rates of (11.9%) low, (9.9%) medium, and (6.9%) high, p=0.005. This level of significance remained for both univariate and multivariate analysis. A similar comparison of outcomes for patients <65 years old did not reach significance in either uni-nor multivariate analysis.


Elixhauser (2003) The United States of America

Low volume (<31) hospitals were compared to high volume hospitals (>31), however this comparison did not demonstrate a significant relationship between increased volume and decreased patient mortality for unruptured abdominal aortic aneurysms.


Forbes (2005) Canada

Patient In-hospital mortality and Length of Stay did not differ between hospital size or teaching status.


Goodney (2003) The United States of America It is likely that the patient cohort used in this study contains individuals from Birkmeyer (2002)

Observed mortality rates were significantly lower at very high volume hospitals versus very low volume hospitals. Relative risk for mortality was nearly equal for Abdominal Aortic Aneurysm repair 0.51 (0.49-0.53) vs. 0.54 (0.52-0.56)


Huber (2001) Canada

Small hospitals had higher mortality, morbidity and length of stay rates then any other hospital volume category.

Group Any complication Mortality Length of stay Small 33.7 % 4.9 % 10.3±7.7 Medium 33.6 % 4.4 % 10.1±8.6 Large 31.8 % 4.0 % 10.0±8.0 P value 0.074 0.11 0.27


Manheim (1998) The United States of America

Ruptured

The odds of dying in a hospital which perform 20-49 operations per year was 73.5% of the rate of dying in a hospital which performed <20 operations per year.

The odds of dying in a hospital which perform >50 operations per year was 49.1% of the odds of dying in a hospital which performed <20 operations per year.

Variable Unruptured Abdominal Aortic Aneurysm Ruptured Abdominal Aortic Aneurysm Intercept P<0.001 P<0.001 Hospital Volume 20-49 0.78 P<0.001 0.74 P<0.001 Hospital Volume 50-99 0.84 P=0.017 0.49 P<0.001 n 35 130 7 327


Pronovost (1999) The United States of America

Surgeons who performed <8 vs. >8 operations per year had a higher in-hospital mortality rate (10% vs. 5%, P=0.003). However when this analysis was repeated in a multivariate analysis no significant difference was identified Hospitals which performed <36 vs. >36 operations each year had a higher in-hospital mortality rate (8% vs. 5%, P=0.005) Hospitals which performed <36 operations each year had an adjusted in-hospital mortality OR= 1.7 (1.3 – 2.3) p<0.05 Hospitals which performed <36 operations each year had an adjusted estimated increase in overall length of stay OR= 6 (-3 – 15) Hospitals which performed <36 operations each year had an adjusted estimated increase in ICU days stay OR= -22 (-43 – 0)

Appendix C 1.2: Volume outcome tables – Abdominal Aortic Aneurysm (continued) Authors Volume outcome

Sollano (1999) The United States of America

A significant inverse relationship between hospital volume and mortality was reported; (OR, 0.782 for hospital volume/100 cases 95% CI, 0.722,0.847; P<0.001)


Trivedi (2006) The United States of America

After adjustment Low Volume Hospitals had an increased odds of mortality rate of 130% relative to High Volume Hospitals. The absolute difference in mortality between the highest and lowest volume category was 12.6% for non-elective AAA. For elective Abdominal Aortic Aneurysm the adjusted Black-White mortality difference was 3.5% in Low Volume compared to 3.9% in High Volume Hospitals.


Tu (2001)) Canada

The risk adjusted mortality rate was significantly higher for general surgeons at 6.2% (95% CI; 5.1-7.3) compared with vascular surgeons 3.5 (95% CI; 2.9-4.1), and cardiac surgeons at 4.0% (1.4-6.6) Low surgeon volume was associated with higher 30 day mortality rates in univariate analyses (7.10% for <5 cases, vs. 5.47 for 5-13 cases per year vs. 3.55 for >13 cases per year, P<0.001).

Annual surgeon volume Regression coefficient Odds Ratio 95% CI P Value <5 0.6064 1.83 (1.01 – 3.32) 0.0452 5-13 0.3333 1.40 (0.97 – 2.02) 0.0755 >13 1.00


Urbach (2003) Canada

Patients treated for unruptured abdominal aortic aneurysms had a significantly higher mortality rate

Low Medium High Very High P value Risk of death (%) 4.8 5.4 3.3 3.2 <0.01 Adjusted Relative Risk of death (95% CI)

1.5 (1.0-2.2)

1.8 (1.2-2.8)

1.0 (0.7-1.5)

1.0 <0.01

Appendix C 1.3: Financial Data – Abdominal Aortic Aneurysm Authors Financial data


Effect of hospital volume on charges

Class n Charge ($) Low 147 31,105 ± 2,154 Medium 191 25,243 ± 1,471 High 189 25,624 ± 1,427 P 0.10

Effect of surgeon volume on charges

Class n Charge ($) Low 315 27,362 ± 1,283 Medium 121 28,575 ± 1,748 High 91 23,740 ± 2,356 P 0.018

Effect of age on Ruptured Abdominal Aortic Aneurysm patients

All patients Charge ($) <65 25,066 ± 2,017 65-69 26,960 ± 2,401 70-79 28,248 ± 1,498 ≥80 25996 ± 1999 P 0.51 Survivors <65 27, 280 ± 2573 65-69 29,340 ± 2,893 70-79 33,433 ± 2,290 ≥80 30,324 ± 3,603 P 0.014 Non-survivors <65 19,454 ± 2,655 65-69 22,899 ± 4,192 70-79 23,397 ± 1,861 ≥80 23,831 ± 2,371 P 0.95



Effect of gender on hospital cost

Gender Charge ($) Male 27,092 ± 1,044 Female 26,716 ± 2,333 P 0.63

Effect of race

Gender Charge ($) Black 26,866 ± 993 White 29,485 ± 3,977 P 0.21

Year Charge ($) 1990 24,818±2838 1991 25,353±2,207 1992 24,138±2457 1993 27,787±2070 1994 26,763±1875 1995 32,671±2467 P 0.003



Influence of patient age on cost.

Age group Hospital Charge ($) <65 15,477±517 65 to 69 16,454±410 70 to 79 18,224±439 ≥80 21,291±1148 p value <0.0001

Influence of Hospital volume on cost

Volume category Hospital Charge ($) Low volume 19,153±550 Medium volume 16,618±467 High volume 17,148±421 p value <0.001

Influence of Surgeon volume on cost

Volume category Hospital Charge ($) Very Low volume 32,800±4,091 Low volume 18,509±699 Medium volume 16,611±293 High volume 17,843,±532 Very High volume 16,682±871 p value <0.001

Mean hospital charge $17,589±276

Appendix C 1.3: Financial Data – Abdominal Aortic Aneurysm (continued) Authors Financial data

Huber (2001) The United States of America

Influence of patient demographics on cost

Patient characteristics Charges ($) Sex Male 35,199±33,035 Female 37,565±32,830 p Value <0.05 Race White 35,645±33,040 Black 41,909±36,921 Other 40,491±40,533 P Value <0.0001 Age 50-59 30,330±23,691 60-69 32,569±27,910 70-79 36,802±35,231 >79 41,082±37,687 P Value <0.0001

Mean Hospital charges $35,681±$33,006 Median Hospital charges $28,052 Impact of characteristics on outcome

Group Charges ($) Non-teaching 35,165±28,796 Teaching 36,750±40,240 P value <0.05 Rural 27,965±19,813 Urban 36,310±33,789 P value <0.0001 Small 36,706±29,865 Medium 36,580±33,653 Large 35,256±33,057 P value 0.06


STUDY DESIGN TABLES

Appendix C 2.1: Study design tables – Knee

Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Feinglass (2004) Chicago The United States Of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =2986


Age: 69 years Hospital Number: Hn =63



Low Medium High 7 - 48 49 - 98 >98

Surgeon: NA End Points: Morbidity:

Low Medium High 6.9 % 9.7 % 8.1 %

Reported as the ‘Overall Complication Rate’

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1993 - 1999 Outcome Measures: Mean length of stay Overall complication rate Major Complication Rate Data Source: Illinois Hospital and Health Systems Association COMPdata files

Condition: Mechanical complications of an internal device 80% (approx) Infections attributable to an internal device 12.5%. Procedure: Revision Total Knee Arthroplasty ICD- 9 Classification: 81.55 Training Hospital: 7 hospitals were included with Orthopaedic training programs, two of which were High Volume Hospitals. The remaining 5 were un specified Institutional/Environmental Support: NR Selective Referral: NR Covariates:

Low Medium High 34.6% 36.0% 2806%

Age: A subgroup of patients older than 74 were investigated in terms of complication incidence

Inclusion criteria: NR Exclusion criteria: Patients admitted to included hospitals who lived outside the sample population

Appendix C 2.1: Study design tables – Knee (continued)

Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Feinglass (2004) (Cont.) Chicago The United States Of America

Mortality:

Low Medium High 2.2 % 3.3 % 2.8 %

Reported as the ‘Major Complication Rate’, this variable combines incidences of death with acute myocardial infarction, stroke acute renal failure and cardiac arrest. Length of stay: (mean, days)


Race: ‘American population’ (%)


Total=11.9% Sex: 64% female Comorbidities:* Coronary Artery Disease Previous Myocardial infarction Chronic obstructive pulmonary Disease Diabetes Heart Failure Cerebrovascular disease Gastrointestinal Ulcer Peripheral vascular disease Chronic liver disease Chronic Renal disease Dementia Paraplegia Cancer other than skin cancer Other:

Low Medium High 8.6% 6.6% 6.6%

Based on ICD-9 codes


Table 10: Random effects Multiple Logistic Regression Results: Effects of Casemix and Hospital Volume on Complication Incidence

Volume Hospital Odds Ratio 95% Confidence Interval Significance Age >74 1.31 1.00 – 1.73 0.05 Patients with any comorbidity* 1.46 1.18 – 2.72 0.005 Emergent or trauma admission 1.79 1.18 – 2.72 0.006 Low 1.00 Medium 1.44 1.05 – 1.99 0.02 High 1.33 0.87 – 2.03 0.17 *These comorbid conditions were only recorded by the authors as being either present or absent.


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Hervey (2003) North Carolina The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume Population Number: Pn =55510 Primary Knee Arthroplasty n= 50874 Revision Knee Arthroplasty n= 4636 Age: mean Primary Knee Arthroplasty 69.1 Revision Knee Arthroplasty 68.6 Hospital Number: See Table 1: Distribution by hospital and Surgeon Procedure Volumes of Primary Total Knee Arthroplasty (%) See Table 2: Distribution by Hospital and Surgeon Procedure Volumes of Revision Total Knee Arthroplasty (%) Surgeon Number: See Table 1: Distribution by hospital and Surgeon Procedure Volumes of Primary Total Knee Arthroplasty (%) See Table 2: Distribution by Hospital and Surgeon Procedure Volumes of Revision Total Knee Arthroplasty (%) Volume Definitions: Hospital:

Low Medium High Very High <85 85 - 149 150 - 249 ≥250

The classifications of low, medium etc were not used by the original authors, but have been added into this document for clarity.

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1997 Outcome Measures: In-hospital Mortality Rates In-hospital Postoperative Complication Rates ▪ Pulmonary embolus ICD-9-cm ▪ Deep Venous Thrombosis (lower) ▪ Postoperative wound infection Length of Stay Data Source: Health Care Cost and Utilization Project (HCUP), Nationwide Inpatient Sample, Release 6

Condition: NR Procedure: Primary Total Knee Arthroplasty Revision Total Knee Arthroplasty ICD- 9 Classification: ICD-9-CM Primary Total Knee Arthroplasty: 81.54 Revision Total Knee Arthroplasty:81.55 Training Hospital: Included not reported separately Institutional/Environmental Support: NR Selective Referral: NR Covariates: Primary Knee Arthroplasty Age: mean 69.1 Race: (%) White: 178,480 (70.2) Non-white: 22,710 (8.9) Missing: 53,180 (21.0) Revision Knee Arthoplasty Age: mean 68.6

Inclusion criteria: Patients with ICD -9 – CM diagnosis of ▪ 81.54 ▪ 81.55 Exclusion criteria: If a patient discharge abstract contained ICD-9-CM procedure codes for revision and primary knee arthroplasty, two codes for primary arthroplasty or two codes for revision arthroplasty the abstract was excluded. Primary Knee arthroplasty Patients were excluded from this group if they had a primary or secondary diagnosis of osteomyelitis, periostitis, or another type of bone infection, a pathological fracture secondary to a malignant neoplasm or codes that suggest complications from a previous arthroplasty. Revision knee arthroplasty. Patients were excluded from this group if they had diagnosis codes which suggested pathological fracture, metastatic cancer or primary malignant bone neoplasm

Appendix C 2.1: Study design tables – Knee (continued) Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria

Hervey (2003) (Cont.) North Carolina The United States of America

Surgeon:

Low Medium High Very High <15 15 - 29 30 - 59 ≥60

The classifications of low, medium etc were not used by the original authors, but have been added into this document for clarity. (performed in 1997) End Points: Morbidity: (overall)

Primary Arthroplasty Revision Arthroplasty Deep venous Thrombosis 242 12 Postoperative infection 127 21 Pulmonary Thromboembolism

190 11

Postoperative complication total

559 44

Mortality:

Primary Arthroplasty Revision Arthroplasty Death 109 8

Length of stay: (overall)

Primary Arthroplasty Revision Arthroplasty Length of stay 4.6 4.9

Race: (%) White: 16,365 (70.6) Non-white: 2200 (9.5) Missing: 4615 (19.9) Sex:

Primary Revision Male 93 755

(36.9) 9 665 (41.5)

Female 160 585 (63.1)

13 515 (58.3)

Missing 30 (0.01) NR Other: Covariates: Patient Covariates Primary Total Knee Arthroplasty Revision Knee Arthroplasty Type of admission Median Income Comorbidity Arthritis Diagnosis Patient Disposition Other: Hospital Covariates Number of beds Religion Ownership Teaching status


Table 11: Distribution by hospital and Surgeon Procedure Volumes of Primary Total Knee Arthroplasty (%)

Surgeon Volume Hospital <15 15 - 29 30 – 59 ≥60 <85 10.1 9.0 5.9 1.2 85 – 149 6.2 5.7 7.4 3.1 150 – 249 4.1 4.8 5.6 8.1 ≥250 3.5 4.5 6.5 14.4 Totals 23.9 24.0 25.4 26.8

Table 12: Distribution by Hospital and Surgeon Procedure Volumes of Revision Total Knee Arthroplasty (%)

Surgeon Volume Hospital <15 15 - 29 30 – 59 ≥60 Total <85 7.2 6.8 5.3 0.9 20.2 85 – 149 5.0 4.6 6.8 2.0 18.4 150 – 249 3.3 4.7 5.3 9.8 23.1 ≥ 250 3.1 6.9 7.0 21.3 38.3 Totals 18.6 23.0 24.4 34.0

Table 13: Adjusted estimates for both Primary Knee Arthroplasty and Total Knee Revision.

Provider/Volume of Total knee arthroplasties Length of Hospital Stay (Days) 95% CI Surgeon <15 4.99 4.97 – 5.02 15 – 29 4.70 4.66 – 4.70 30 – 59 4.75 4.72 – 4.77 ≥60 4.27 4.22 – 4.32 Hospital <85 5.00 4.99 – 5.02 85 – 149 4.85 4.82 – 4.87 150 – 249 4.41 4.37 – 4.44 ≥250 4.43 4.38 – 4.47


Table 14: Relationship between Surgeon volume and select outcomes

Volume of Knee arthroplasties Outcome Rate % Adjusted Ratio Mortality <15 0.31 1 15 – 29 0.21 0.66 (0.30 – 1.46) 30 – 59 0.20 0.58 (0.24 – 1.41) ≥60 0.20 0.56 (0.24 – 1.31) Deep Venous Thrombosis <15 0.67 1 15 – 29 0.43 0.79 (0.47 – 1.33) 30 – 59 0.38 0.77 (0.34 – 1.72) ≥60 0.53 0.84 (0.43 – 1.67) Postoperative Infection <15 0.44 1 15 – 29 0.24 0.46 (0.22 – 0.95) 30 – 59 0.23 0.64 (0.33 – 1.26) ≥60 0.21 0.57 (0.28 – 1.14) Pulmonary Thromboembolism <15 0.37 1 15 – 29 0.37 1.21 (0.60 – 2.42) 30 – 59 0.33 0.69 (0.32 – 1.47) ≥60 0.33 0.90 (0.45 – 1.82)

Table 15: Relationship between Hospital volume and select outcomes

Volume of Knee Arthroplasties Outcome Rate % Adjusted Ratio Mortality <85 0.30 1 85 – 149 0.16 0.52 (0.20 – 1.36) 150 – 249 0.19 0.42 (0.20 – 0.90) ≥250 0.21 0.40 (0.18 – 0.87) Deep Venous Thombosis <85 0.34 1 85 – 149 0.46 1.07 (0.45 – 2.55) 150 – 249 0.59 2.52 (1.12 – 5.68) ≥250 0.42 1.87 (0.73 – 4.79) Postoperative Infection <85 0.32 1 85 – 149 0.37 1.18 (0.57 – 2.44) 150 – 249 0.29 1.01 (0.51 – 2.01) ≥250 0.12 0.32 (0.10 – 1.12) Pulmonary Thromboembolism <85 0.38 1 85 – 149 0.33 1.13 (0.58 – 2.18) 150 – 249 0.31 1.35 (0.72 – 2.55) ≥250 0.34 1.10 (0.53 – 2.26)


Husted (2006) The Netherlands


Low Medium High Total 357 622 3170 6710

Age: NR Hospital Number: Hn =

Low Medium High Total 14 8 19 41


Low Medium High <50 50 - 99 >100

Surgeon: NA End Points: NR Morbidity: NR Mortality: NR Length of stay: NR

Level of Evidence: CNB Follow-up: NR Lost to Follow-up: NR Study Period: 2004 Outcome Measures: Duration of stay 30 day readmission Mortality (30 and 90 day) Data Source: National Register of Patients (Denmark)

Condition: Knee Resection Procedure: Total Knee Replacement ICD- 9 Classification: NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: NR Age: NR Race: NR Comorbidities: NR



Judge (2006) The United Kingdom

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 211,099 (Knees) Age: NR Hospital Number: Hn = NR Surgeon Number: Sn = NA Volume Definitions: A priori decision – clinically sensible categories Hospital:

Very Low Low Medium High Very High 1 - 50 51 - 100 101 - 250 251 - 500 >500

Surgeon: NA End Points: Morbidity: NR Mortality: See Table 17: Odds Ratios (OR) for in-hospital mortality for TKR 1997 - 2002 Length of stay: See Table 18:Length of Stay

Level of Evidence: III-3 Follow-up: 1997 patient cohort: 5 years 1998 – 2002: 30 Days Lost to Follow-up: NR Study Period: 1997 – 2002 (Financial years) Outcome Measures: 30-day in-hospital mortality Length of stay Readmission within a year Surgical revision within 5 years Data Source: Hospital Episode Statistics

Condition: NR Procedure: Total Knee Replacement ICD- 10 Classification: Revised surgery was identified fromT85 ICD-10 codes. Patients were also identified from OPCS4 codes ( W40, W41, W42) Training Hospital: Training Hospitals were included but numbers not reported or were reported separately. Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Adjusted not reported Race: NR Sex: Adjusted not reported Comorbidities: Charlson

Inclusion criteria: Revised surgery was identified fromT85 ICD-10 codes. Patients were also identified form OPCS4 codes ( W40, W41, W42) Exclusion criteria: Patients were excluded if their records did not classify their treatment as containing ‘Trauma’ and ‘Orthopaedics’ HES excludes private procedures


Table 16: Number of Knee Replacements per hospital in 1997 and 2002

Very Low Low Medium High Very High Year 1 - 51 51 - 100 101 - 250 251 - 500 >500

1997 433 (1.6) 5234 (19.4) 14460 (53.5) 6350 (23.5) 531 (2.0) 2002 42 (0.1) 584 (1.3) 13687 (30.7) 19850 (44.5) 10462 (23.4)

Table 17: Odds Ratios (OR) for in-hospital mortality for TKR 1997 – 2002

Volume of Trust Total number of operations In-hospital deaths within 30-days (% of total)

Crude OR (95% CI)

Adjusted OR (95% CI)

1 – 50 1053 6 (0.57) 1.86 (0.83 – 4.19) 1.72 (0.76 – 3.89) 51 – 100 13625 56 (0.41) 1.34 (1.01 – 1.79) 1.30 (0.97 – 1.74) 101 – 250 99824 306 (0.31 1.00 1.00 251 – 500 64822 172 (0.27) 0.87 (0.72 – 1.04) 0.87 (0.72 – 1.05) >500 25977 52 (0.20) 0.65 (0.49 – 0.88) 0.62 (0.45 – 0.85) Training Centre Training Centre 39387 99 (0.25) 1.00 1.00 Other 165934 493 (0.30) 1.18 (0.95 – 1.47) 0.98 (0.78 – 1.24) Admission Type Elective 201661 543 (0.27) 1.00 1.00 Emergency 3411 45 (1.32) 4.95 (3.65 – 6.72) 3.95 (2.82 – 5.52) Charlson Co-morbidity Index None 34939 91 (0.26) 1.29 (1.02 – 1.64) 1.11 (0.86 – 1.43) Mild 152973 308 (0.20) 1.00 1.00 Moderate 15278 146 (0.96) 4.78 (3.92 – 5.83) 4.98 (4.08 – 6.08) Severe 2131 47 (2.21) 11.18 (8.20 – 15.24) 9.29 (6.78 - 12.74)


Table 18: Length of Stay

Volume of Trust Mean (SD) Median (Interquartile Range) 1 – 50 14.2 (9.5) 12 (10 – 16) 51 – 100 13.7 (10.9) 12 (9 – 15) 101 – 250 12.1 (10.0) 10 (8 – 14) 251 – 500 11.2 (8.9) 9 (7 – 13) >500 10.6 (8.4) 9 (7 – 12) Training Centre Training Centre 11.7 (10.7) 10 (7 – 14) Other 11.8 (9.3) 10 (8 – 14)

Table 19: Hazard of revision surgery within 5 years of primary procedure

Volume of Trust Total number of primary operations Number of revisions (% of total) Crude Hazard Ratio (95% CI) Adjusted Hazard Ratio (95% CI) 1 – 50 376 16 (4.26) 0.82 (0.50 – 1.35) 0.81 (0.49 – 1.32) 51 – 100 4697 220 (4.68) 0.91 (0.78 – 1.06) 0.94 (0.81 – 1.10) 101 – 250 12841 661 (5.15) 1.00 1.00 251 – 500 5503 281 (5.11) 0.99 (0.86 – 1.14) 0.99 (0.86 – 1.15) >500 428 32 (7.48) 1.49 (1.04 – 2.12)* 1.57 (1.07 – 2.30)* Training Centre Training Centre 4222 218 (5.16) 1.00 1.00 Other 19623 992 (5.06) 0.98 (0.85 – 1.14)** 1.07 (0.91 – 1.25)** *Proportional hazards assumption was not satisfied. Fitting volume (>500) as a time varying variable found that the hazards was significantly higher up to 6 months after admission, but from then in there was no difference with the baseline category

**The proportional hazards assumption was not satisfied for training centre. Fitting a time variable found that the hazard was significantly increased up to 6 months after admission, but no difference was observed from then onwards.


Katz (2004) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume Population Number: Pn =80904 Age: NR Hospital Number: Hn = NR Surgeon Number: Sn = NR Volume Definitions: Numbers of 10 and revisions TKA in Medicare population performed during 2000 Hospital:

Low Medium High Very High 1 - 25 26 - 100 101 - 200 >200

Surgeon:

Low Medium High Very High 1 - 12 13 - 25 26 - 50 >50

End Points:

Morbidity: See Table 20: Association between hospital volume and patient morbidity Mortality: See Table 21: Association between hospital volume and patient mortality Length of stay: NR

Level of Evidence: III-3 Follow-up: 90 days (at least) Lost to Follow-up: NR Study Period: Patients were enrolled between January 1 – August 31/ 2000, and followed for 90 days Outcome Measures: Death Myocardial Infarction Deep Wound Infection Pneumonia Pulmonary Embolus (ICD 415.1 – 415.19) Data Source: Medicare claims forms

Condition: NR Procedure: Total Knee Replacement (primary) ICD- 9 Classification: 81.54 (+ CPT 27447) Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Adjusted not reported (75+ years) Sex: Adjusted not reported Race: Adjusted not reported Medicaid: Adjusted not reported Arthritis diagnosis: Osteoarthritis Rheumatoid arthritis Other

Inclusion criteria: Patients were enrolled if their procedure was Classified as ICD-9 81.54; or 27447 by the Current Procedural Terminology. Exclusion criteria: Patients were excluded if they had indications of existing infection of the knee, metastatic cancer, or bone cancer. Patients were also excluded if they were enrolled in HMOs, if they were not enrolled in both parts of Medicare, less than 65 and not residents of the United States Patients who had bilateral total knee replacements n the same hospitalization


Katz (2004) (Cont.) The United States of America

Comorbidities: Acute: Pulmonary Embolus Myocardial Infarction Pneumonia (Charlson) Chronic: Diabetes

Table 20: Association between Hospital Volume and patient morbidity

Hospital Acute Myocardial Infarction Percentage of Patients with Outcome Adjusted OR (95 % CI) P value for trend 1 – 25 0.95 1.00 0.454 26 – 100 0.78 0.86(0.62 - 1.21) 101 – 200 0.84 0.96 (0.66 – 1.37) >200 0.70 0.79 (0.52 – 1.20 ) Pulmonary Embolus 1 – 25 0.88 1.00 0.372 26 – 100 0.81 0.95 (0.67 – 1.33) 101 – 200 0.75 0.86 (0.58 – 1.28) >200 0.75 0.88 (0.57 – 1.36) Pneumonia 1 – 25 1.93 1.00 <0.001 26 – 100 1.46 0.80 (0.62 – 1.03) 101 – 200 1.18 0.71 (0.53 – 0.96) >200 1.06 0.65 (0.47 – 0.90) Deep Infection 1 – 25 0.55 1.00 0.075 26 – 100 0.39 0.80 (0.50 – 1.28) 101 – 200 0.36 0.84 (0.49 – 1.43) >200 0.23 0.61 (0.33 – 1.16)


Table 20: Association between Hospital Volume and patient morbidity, (cont.)

Pneumonia, Pulmonary Embolus or Acute Myocardial Infarction

1 – 25 3.5 1.00 0.004 26 – 100 2.8 0.85 (0.71 – 1.02) 101 – 200 2.6 0.82 (0.67 - 1.01) >200 2.4 0.75 (0.60 – 0.94) Pneumonia, Pulmonary Embolus, Acute Myocardial Infarction, or Death

1 – 25 4.6 1.00 <0.001 26 – 100 3.6 0.83 (0.71 – 0.98) 101 – 200 3.4 0.82 (0.68 – 0.99) >200 3.0 0.74 (0.60 – 0.90)

Table 21: Association between Hospital Volume and patient mortality

Hospital Death Percentage of Patients with Outcome Adjusted OR (95 % CI) P value for trend 1 – 25 0.92 1.00 0.189 26 – 100 0.58 0.67 (0.47 – 0.95) 101 – 200 0.62 0.73 (0.49 – 1.08) >200 0.58 0.69 (0.45 – 1.05)


Table 22 Association between Surgeon Volume and Patient with select outcome

Surgeon Annual Procedure Volume Percentage of Patients with Outcomes Adjusted OR (99% CI) P Value for Trend 1 – 12 Death 0.67 1.00 0.782 13 – 25 0.65 1.00 (0.72 – 1.38) 26 – 50 0.60 0.94 (0.67 – 1.33) >50 0.58 0.97 (0.66 – 1.43) 1 – 12 MI 0.80 1.00 0.426 13 – 25 0.87 1.11 (0.83 – 1.47) 26 – 50 0.81 1.03 (0.76 – 1.40) >50 0.69 0.90 (0.64 – 1.28) 1 – 12 PE 0.76 1.00 0.688 13 – 25 0.84 1.14 (0.85 – 1.53) 26 – 50 0.79 1.10 (0.81 – 1.50) >50 0.74 1.06 (0.73 – 1.54)) 1 – 12 Pneumonia 1.68 1.00 0.002 13 – 25 1.41 0.87 (0.70 – 1.08) 26 – 50 1.26 0.82 (0.64 – 1.04) >50 1.02 0.72 (0.54 – 0.95) 1 – 12 Deep infection 0.55 1.00 0.006 13 – 25 0.32 0.61 (0.41 – 0.91) 26 – 50 0.29 0.57 (0.37 – 0.89) >50 0.29 0.62 (0.37 – 1.06) 1 – 12 Pneumonia/PE/acute MI 3.1 1.00 0.023 13 – 25 2.9 0.98 (0.84 – 1.15) 26 – 50 2.7 0.92 (0.78 – 1.09) >50 2.3 0.84 (0.68 – 1.03) 1 – 12 Pneumonia/ PE/MI/infection/death 4.0 1.00 0.003 13 – 25 3.6 0.93 (0.81 – 1.07) 26 – 50 3.4 0.88 (0.76 – 1.02) >50 2.9 0.81 (0.68 – 0.98)


Kreder (2003) Canada

Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume Population Number: Pn = 14352 Age: See Table 13: Patient Characteristics Hospital Number: Hn =88

Low Medium High Volume Percentile <40 40 - 80 >80 Providers no. 35 36 17 Patient/Year no. <48 48 - 113 >113 Total Patients 1914 6127 6311 Average Hospital Volume/year

31.9 82.5 237.4

Average Surgeon Volume/year

28.3 39.2 65.8

Surgeon Number: Sn =262

Low Medium High Volume Percentile <40 40 - 80 >80 Providers no.* 108 108 51 Patient/Year no. <14 14 - 42 >42 Total Patients 1463 5745 7144 Average Hospital Volume/year

76.9 99.4 62.8

Average Surgeon Volume/year

8.9 28.0 75.0

* Total does not equal reported total of 262 Volume Definitions: Number TKA averaged over 4 years

Level of Evidence: III-3 Follow-up: Minimum 3 years Maximum 5 years Lost to Follow-up: NR Study Period: April 1992 – March 1996 Outcome Measures: Average Length of Stay Complications during hospital admission Death Infection Revision Excision Amputation Deep Venous Thrombosis Data Source: The Ontario Health Institute Plan (OHIP), supplemented with data from the Canadian Institute for Health Information Ontario mortality file

Condition: Inflammatory or degenerative arthritis Procedure: Total Knee Arthroplasty ICD- 9 Classification: 81.51, or 81.59 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Adjusted not reported Race: Adjusted not reported Sex: Adjusted not reported Comorbidities: Adjusted not reported (Charlson index) Other: Surgical Diagnosis: Adjusted not reported

Inclusion criteria: Patients with inflammatory or degenerative arthritis Exclusion criteria: NR


Kreder (2003) (Cont.) Canada

Hospital:

Low Medium High <40th percentile 40 – 80th percentile >80th percentile

Surgeon: percentiles not absolute numbers


End Points: Morbidity: See Table 24: Patient Characteristics Mortality: See Table 25: Patient Characteristics Length of stay: See Table 26: Adjusted changes in length of stay


Table 23: Patient Characteristics

Surgeon Hospital Patients Per Year <14 9 (med) 14 - 42 (med) >42 (high) <48 (low) 48 - 120 (med) >120 (high) Average age 70.1 70.0 69.2 70.1 70.0 69.1 Comorbidity >0 20.4 20.3 21.4 18.1 20.8 21.7 >1 0.5 0.6 0.4 0.7 0.5 0.5 Men 41.6 37.2 37.9 40.7 37.6 37.6 Inflammatory Arthritis 8.3 8.0 9.7 5.6 9.3 9.5 Average Length of Hospital Admission (days)

11.5 10.5 10.0 10.8 10.5 10.0

Complications during hospital index admission

9.0 9.8 11.0 6.6 10.0 11.8

Death During index hospital admission

0.5 0.5 0.3 0.5 0.4 0.3

Within 3 months 0.8 0.6 0.4 0.7 0.06 0.4 Infection Within 1 yr 1.4 1.4 1.5 1.9 1.4 1.4 Within 3 yr 2.1 2.1 2.3 2.7 2.1 2.1

Table 24: Patient Characteristics (Cont.)

Surgeon Hospital Revision Within 1 yr 0.6 0.9 0.8 1.1 0.9 0.6 Within 3 yr 2.2 2.0 1.9 2.5 2.1 1.7 Excision Within 1 yr 0.4 0.2 0.4 0.3 0.4 0.3 Within 3 yr 0.8 0.6 0.8 0.6 0.8 0.7 Amputation within 3 yr 0 0.07 0.03 0.05 0.05 0.03 Deep Venous Thrombosis within 3 months

1.8 2.9 2.6 1.7 3.3 2.3


Table 25: Adjusted complication rates by provider volume, patient age, co-morbidity, diagnosis and sex

Variable Readmission for Knee Infection or 95% CI Readmission for Knee Revision or 95% CI Patient Death or 95% CI In-hospital Complications or 95% CI

1yr 3yr 1yr 3yr <3 months Surgeon Volume Low <14 vs. high>42 0.80 (0.4 – 1.6) 0.88 (0.5 – 1.3) 0.57 (0.2 – 1.4) 1.00 (0.6 – 1.7) 1.76 (0.80 – 3.8) 0.98 (0.7 – 1.3) Mid 14-42 vs. high>42 0.84 (0.6 – 1.2) 0.83(0.6 – 1.1) 0.91 (0.5 – 1.6) 0.97 (0.7 – 1.4) 1.61 (0.9 – 2.7) 0.99 (0.76 – 1.27) H ospital Volume Low <48 vs. high >113 1.57 (0.9 – 2.7) 1.5 (0.9 – 2.3) 2.23 (1.1 – 4.5)* 1.54 (1.0 – 2.4)* 1.38 (0.7 – 2.9) 0.53 (0.39 – 0.71) Low 48 – 113 vs. high >113

1.11 (0.8 – 1.6) 1.10 (0.8 – 1.5) 1.57 (0.9 – 2.9) 1.25 (0.9 – 1.8) 1.30 (0.8 – 1.5) 0.83 (0.63 – 1.07)

Patient age per 10 yr 0.90 (0.86 – 0.97)* 0.90 (0.85 – 0.95)* 0.77 (0.67 – 0.89)* 0.70 (0.66 – 0.81)* 2.44 (2.3 – 2.6)* 1.19 (1.1 – 1.2)* Patient Comorbidity 1 vs. 0 0.67 (0.4 – 1.6) 0.92 (0.6 – 1.3) 1.15 (0.6 – 2.1) 1.07 (0.7 – 1.5) 5.36 (3.2 – 8.9)* 1.19 (1.0 – 1.4) * >1 vs. 0 1.69 (0.9 – 3.3) 2.14 (1.3 – 3.6)* 0.80 (0.2 – 2.6) 0.88 (0.4 – 1.8) 23.70 (13.3 – 42.1)* 2.05 (1.6 – 2.62)* Osteoarthritis vs. Non-osteoarthritis

0.55 (0.3 – 0.9)* 0.75 (0.5 – 1.2) 1.10 (0.5 – 2.6) 1.26 (0.8 – 2.1) 1.27 (0.7 – 2.4) 0.96 (0.76 – 1.22)

Female vs. male 0.8 (0.6 – 1.0) 0.78 (0.6 – 0.9)* 0.91 (0.6 – 1.3) 0.95 (0.7 – 1.2) 0.66 (0.4 – 1.0) 0.71 (0.6 – 0.8)* * Statistically significant

Table 26: Adjusted changes in length of stay

Variable Stay Mean extra days (95% confidence linits) Surgeon Volume Low <14 v. high>42 1.4 (1.2 – 1.9)* Mid 14-42 v. high>42 0.5 (-0.1 – 0.7) Hospital Volume Low <48 v. high >113 0.8 (0.5 – 1.1)* Low 48 – 113 v. high >113 0.4 (0.2 – 0.6)* Patient age per 10 yr 0.7 (0.5 – 0.8)* Patient Comorbidity 1 v. 0 0.9 (0.5 – 1.2)* >1 v. 0 2.8 (1.8 – 3.7)* Osteoarthritis v. Non-osteoarthritis 0.2 (-0.6 – 0.2) Female v. male 0.4 (0.2 - 0.6)* * Statistically significant


Mitsuyasu (2006) Japan

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 734

Low 277 High 457 Total 734

Age: Mean, [SD]

Low 72.32 [8.23] High 70.40 [9.36]

Hospital Number: Hn =19



Low <40 High 40 – 160

Surgeon: NA End Points: Morbidity: NR Mortality: NR

Level of Evidence: III-2 Follow-up: NR Lost to Follow-up: NR Study Period: April 1/2001 – March 31/2003 Outcome Measures: Hospital Charges Total Length of Stay Preoperative length of stay Postoperative length of stay Data Source: Japanese DRG/PPS Versions 1 and 2

Condition: Osteoarthritis (OA) Non - OA Procedure: Total Knee Replacement ICD- 9 Classification: 81.54 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: See Table 17: Total Knee Replacement patient Characteristics Race: NR Sex: See Table 17: Total Knee Replacement patient Characteristics Comorbidities: See Table 17: Total Knee Replacement patient Characteristics



Mitsuyasu (2006) (Cont.) Japan

Length of stay: See Table 28: Total Knee Replacement Length of Stay (LOS) in days

Other: Transfer to another hospital: See Table 29: Total Knee Replacement patient Characteristics Diagnosis: See Table 29: Total Knee Replacement patient Characteristics

Table 27: Total Knee Replacement Length of Stay (LOS) in days

Mean LOS (total) (days) Preoperative LOS Postoperative LOS High Volume Low Volume P High Volume Low Volume P High Volume Low Volume P Total Knee Replacement 39.24 ± 18.09 54.44 ± 26.60 <0.001 6.47 ± 9.35 10.00 ± 13.72 <0.001 32.77 ± 13.15 44.45 ± 17.83 <0.001 Osteoarthritis 39.13 ± 14.29 51.19 ± 17.66 <0.001 5.94 ± 6.83 8.53 ± 9.26 <0.001 33.18 ± 11.25 42.65 ±13.34 <0.001 Non-Osteoarthritis 39.42 ± 22.77 63.55 ± 41.47 <0.001 7.28 ± 12.24 14.08 ± 21.37 0.01 32.14 ± 15.64 49.47 ±26.13 <0.001

Table 28: Total Knee Replacement Patient Characteristics

High Volume Low Volume P Mean Age ± SD 70.40 ± 9.36 72.32 ± 8.23 <0.01 Female Sex % 84.03 83.03 0.72 No. of Comorbidities 0 62.80 60.29 0.50 1≥ 37.20 39.71 Transfer to hospital % Yes 92.34 90.97 0.51 No 7.66 9.03 Diagnosis % OA 60.61 73.65 <0.01 Non-OA 39.39 26.35


Norton (1998) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 295473 Age: (Mean) (74) Hospital Number: Hn = NR Surgeon Number: Sn = NA Volume Definitions: Hospital:

Low Medium High Very High Dummy 0 - 20 21 - 40 41 - 80 >80 0

Surgeon: NA End Points: Morbidity: Reported as a complication. See Table 18: Predicting probability of complication Mortality: Reported as a complication. See Table 18: Predicting probability of complication Length of stay: NR

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1985 – 1990 Outcome Measures: Likely Complication Possible Complication Anaemia Other Data Source: Health Care Finance Administration’s Denominator Files. Health Care Finance Administration’s Area File. American Hospital Association survey file. MEDPAR files

Condition: NR Procedure: Knee Replacement ICD- 9 Classification: 81.41 81.54 81.55 Training Hospital: Reported, not related to volume Institutional/Environmental Support: In-hospital and out-hospital rehabilitation reported, no data provided Selective Referral: NR Covariates: Age: (Mean) (74), not related to volume Race: White: 90% > African American:5% Non-White, Non-African American: 1% Not related to volume Sex: About 1/3rd are men

Inclusion criteria: Patients’ were included if they were over 65, and had a procedure code of: ▪ 81.41 ▪ 81.54 ▪ 81.55 Exclusion criteria: Patients were excluded if they were enrolled in a HMO. Patients whose health status was deemed to be very different to others enrolled Patients who lived outside the United States of America. Patients whose operation was not attempted due to counter indications or patient preference. Obviously miscoded patients. Patients who received treatment outside the hospital setting. Patients who could not be matched to American Hospital Association Data, or those with missing/invalid patient data Re-operation surgery


Norton (1998) (Cont.) The United States of America

Comorbidities: Reported, not related to volume Other: Hospital: For Profit, Government, Orthopaedic, Other Specialty, Multi-hospital System Patient: Age <65, Emergency Admission, Disability, Obese, Obese and Male, Dislocated Knee. Reported, not related to volume

Table 29: Predicting probability of complication#

Likely Complication Possible Complication Anaemia Mean [Range] 0 – 20 -0.0008 -0.0030 0.0048 18.1 (0.0022) (0.0018) (0.0038) [1 – 20] 21 – 40 0.0014 -0.0022 -0.0099* 12.9 (0.0017) (0.0014) (0.0033) [0 – 20] 41 – 80 -0.0047* -0.00250* -0.0024 14.9 (0.0012) (0.00094) (0.0024) [0 – 40] >80 0.00063 0.00042 -0.00091 16.9 (0.00057) (0.00045) (0.00097) [0 – 364] 0 0.076 0.055 0.18 0.0079 (0.078) (0.057) (0.11) #Mortality considered a complication

* Statistically significant

Presences of physical therapy services in the hospital decreased the probability of all three types of complications, but the results were not statistically significant.


Solomon (2006) Atlanta, The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 9073 Age: (Mean), [SD] (74.2) ± [5.8] Hospital Number: (%) Hn =



Low 1-22 High ≥23

Surgeon: NA End Points: Morbidity: Included in ‘Adverse Events’, see Table 31: Multivariate analysis of adverse events Mortality: Included in ‘Adverse Events’, see Table 31: Multivariate analysis of adverse events Length of stay: NR

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 2000 Outcome Measures: 90 day post-operative adverse event, (Death, Deep wound infection, pulmonary embolus, pneumonia requiring hospitalization, and myocardial infarction. Data Source: In-patient Medicare Data (2000) American Hospital Association Annual Survey (2001)

Condition: Osteoarthritis Rheumatoid Arthritis Avascular Necrosis Other Procedure: Primary Total Knee Replacement ICD- 9 Classification: NR Training Hospital: One in five (55.2 approximately) Institutional/Environmental Support: Physical Therapy Initiation Frequency of Physical Therapy Visits Rehabilitation facilities on weekends Care Coordination Reported not related to volume Selective Referral: NR Covariates: Patient Age: (Mean), [SD] (74.2) ± [5.8] Race: Reported not adjusted. Sex: n (%) M/F: 2821(31.1) / 6252 (68.9)

Inclusion criteria: NR Exclusion criteria: Did not respond to survey No Medicare px. undergoing TKR during study period Hospitals that were not ‘confident’ in the accuracy of their responses


Solomon (2006) (Cont.) Atlanta, The United States of America

Comorbidities: Charlson Comorbidity Scale 0 – 5742 (63.3%) 1 – 2107 (23.2%) >1 – 1224 (13.5%) Other: Hospital: Low Volume No pre-operative teaching program No dedicated orthopaedic operating room

Table 30: Multivariate analysis of adverse events

Hospital Volume Model with Hospital Volume Fully adjusted Model Weight in index High ≥23 1.0 1.0 Low <23 1.8 (1.2 – 2.8) 1.6 (1.1 – 2.5) 1.00


SooHoo (2006) California The United States of America


Hospital type Volume N (%) High Volume 128257 (58) Intermediate Volume 79227 (35) Low 15200 (7) Hospital Size (number of beds) Low (<100) 19928 (9) Medium (100 - 199) 50772(23) High (200 - 299) 57626 (26) Very High (>299) 94336 (42) Teaching hospital 21829(10)

Age: Mean, [SD] 69 [± 10] Hospital Number: Hn =

Low Intermediate High 165 165 83


Low Intermediate High 0 - -40th percentile 41 – 80th percentile >81st percentile

Mean annual volume of patients

Low Intermediate High 13 (±5) 50 (± 15) 145 (±47)

Level of Evidence: III-3 Follow-up: 1 year Lost to Follow-up: NR Study Period: 1991 - 2001 Outcome Measures: Mortality Infection Thrombophlebitis Pulmonary embolism Data Source: Office of Statewide Health Planning and Development (OSHPD) California State Death Statistical Master File.

Condition: Procedure: Primary Total Knee Arthroplasty ICD- 9 Classification: 81.54 Training Hospital: Hn = NR Pn = 21829 (10%) Institutional/Environmental Support: NR Selective Referral: NR Covariates: Patient Age: Mean, [SD] 69 [± 10] Race: n (%) White: 178054 (80) Black: 10749 (5) Hispanic: 24474 (11) Asian/Pacific Islander: 5362 (2) Other: 4045 (2) Sex: n (%) M/F: 85189 (38)/137495(62) Comorbidities: Mean, [SD] Mean Charlson Comorbidity score 0.52 [±0.91]

Inclusion criteria: Patients with ICD-9 procedure code 81.54 Exclusion criteria: Patients were excluded if their records reported codes consistent with bone infection, pathological fracture, prior knee arthroplasty undergoing revision


SooHoo (2006) (Cont.) California The United States of America

Surgeon: NA End Points: Morbidity: See Table 20 Odds Ratios for complications at Low and Intermediate Volume Hospitals in comparison to High Volume Hospitals at 90 days and 1 year; AND Table 21: Number of complications at Low, Intermediate and High Volume hospitals at 90 days Mortality: See Table 20 Odds Ratios for complications at Low and Intermediate Volume Hospitals in comparison to High Volume Hospitals at 90 days and 1 year; AND Table 21: Number of complications at Low, Intermediate and High Volume hospitals at 90 days Length of stay: NR

Other: n (%) Bilateral Total Knee Arthroplasty 6918 (3.11) Insurance Type: Medicare: 144873 (65) Medicaid: 7843 (3.5) Private: 60256 (27) Other: 8712 (4.5) Hospital Teaching Status Hospital Size

Table 31: Odds Ratios for complications at Low and Intermediate Volume Hospitals in comparison to High Volume Hospitals at 90 days and 1 year

Complication Low Volume Hospital OR (95% CI, P Value) Intermediate Volume Hospital OR (95% CI, P Value) 90 day Mortality 1.50 (1.14 – 1.98, 0.004) 1.31 (1.09 – 1.58, 0.003) 90 day Infection 1.60 (1.21 – 2.21, 0.001) 1.13 (0.91 – 1.40, 0.270) 90 day Pulmonary Embolism 1.45 (1.07 – 1.97, 0.16) 1.14 (0.95 – 1.37, 0.170) 90 day Thrombophlebitis 2.12 (1.47 – 3.05, ≤0.001) 1.09 (0.80 – 1.48, 0.580) 90 day Combined Mortality and Readmission for any cause 1.50 (1.14 – 1.98, 0.004) 1.31 (1.09 – 1.58, 0.003) 1 Year Mortality 1.19 (1.01 – 1.41, 0.035) 1.18 (1.06 – 1.32, 0.002) 1 Year Infection 1.64 (1.28 – 2.09, ≤0.001) 1.07 (0.89 – 1.30, 0.48) 1 Year Pulmonary Embolism 1.27 (1.03 – 1.56, ≤0.27) 1.16 (1.02 – 1.33, 0.029) 1 Year Thrombophlebitis 1.98 (1.46 – 2.68, ≤0.001) 1.10 (0.86 – 1.41, 0.433) 1 Year Combined Mortality and Readmission for any cause 1.22 (1.12 – 1.32, ≤0.001) 1.12 (1.05 – 1.19, ≤0.001)


Table 32: Number of complications at Low, Intermediate and High Volume hospitals at 90 days

Complications Low Volume Hospitals Intermediate Volume Hospitals High Volume Hospitals No. of complications (%, P Value) No. of complications (%, P Value) No. of complications (%) 90 day Mortality 83 (0.55, 0.004) 467 (0.59, 0.003) 626 (0.49) 90 day Infection 171 (1.13, 0.001) 575 (0.73, 0.270) 840 (0.65) 90 day Pulmonary Embolism 73 (0.48, 0.016) 339 (0.43, 0.170) 502 (0.39) 90 day Thrombophlebitis 74 (0.49, ≤0.001) 218 (0.28, 0.580) 364 (0.28) 90 day Combined Mortality and Readmission for any cause

2171 (14.28, 0.004) 10600 (13.38, 0.003) 15352 (11.97)


Taylor (1997) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 253370*

Low* Medium* High* 6288 14581 101267

Reported as number of cases. Total Knee Arthroplasty - 253370 Knee Revision - 22992 Age: See Table 22 Hospital Number: Hn = Surgeon Number: Sn = NA Volume Definitions: Hospital:

Low Medium High <25 25 - 199 >199


Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1993 - 1994 Outcome Measures: Mortality rates Data Source: Medicare Provider Analysis and Review

Condition: NR Procedure: Total Knee Arthroplasty Knee Revision ICD- 9 Classification: 81.54 81.55 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: See Table 22 Race: NR Sex: See Table 22 Comorbidities: NR



Taylor (1997) (Cont.) The United States of America

Mortality:

ICD-9 Hospital Volume

Total no. of cases

In-house mortality (%)

In-house + 30 day mortality (%)

81.54 Low 6288 0.35 0.73 Medium 145915 0.27 0.52 High 101267 0.22 0.41 81.55 Low 351 0.57 0.57 Medium 11773 0.31 0.54 High 10868 0.25 0.42

Length of stay: NR

Table 33: Age and Sex information by procedure code and Hospital Volume 1993 – 1994

ICD-9 Hospital Volume Total no. of cases Proportion (%) of women Average Age 81.54 Low 6288 68 73.30 (5.26) Medium 145915 66 73.35 (5.27) High 101267 64 73.30 (5.26) 81.55 Low 351 65 73.50 (5.30) Medium 11773 61 73.20 (5.24) High 10868 60 73.20 (5.24)

Table 34: Mortality rates by procedure code 1995*

ICD-9 Hospital Volume Total no. of cases In-house mortality (%) In-house + 30 day mortality (%) 81.54 Low 3235 0.46 0.90 Medium 75463 0.24 0.51 High 57264 0.22 0.43 81.55 Low 178 0.56 1.12 Medium 6141 0.29 0.41 High 6273 0.26 0.38 Outcomes determined from a proposed release of data


Table 35: Age and Sex information by procedure code and Hospital Volume 1995*

ICD-9 Hospital Volume Total no. of cases Proportion (%) of women Average Age 81.54 Low 3235 67 73.20 (5.24) Medium 75463 66 73.35 (5.27) High 57264 64 73.30 (5.26) 81.55 Low 178 67 73.75 (5.35) Medium 6141 61 73.40 (5.28) High 6273 60 73.35 (5.27) Outcomes determined from a proposed release of data

Appendix C 2.2: Volume outcome tables – Knee Authors Volume outcome data

Feinglass (2004) Chicago The United States Of America

A higher complication rank order correlation was reported for higher hospitals (r= 0.27; P=0.035), however 11 low volume hospitals reported no complication, and if these 11 are excluded the complication correlation is insignificant. Medium volume hospitals had the highest complication rates, and the highest volume hospitals had intermediate complication rates.


Hervey (2003) North Carolina The United States of America

Multivariate regression modelling demonstrated higher surgeon volumes were associated with lower mortality rates (P=0.002). Multivariate regression modelling demonstrated higher hospital volumes were significantly associated with lower mortality rates (P=0.003) Surgeon volume of <15 was associated with complications such as: Deep venous thrombosis, and post operative infection No additional variables were associated with an incremental relative risk.


Husted (2006) The Netherlands

No volume outcome data was reported in this study.

Appendix C 2.2: Volume outcome tables – Knee (continued) Authors Volume outcome data

Judge (2006) The United Kingdom

No relationship between and increase in volume and a decrease in readmission was reported for Knee Arthroplasty. No demonstrated non-linearity was found (P=0.33) The adjusted model demonstrated that the log hazard increases by 0.06 (95% CI; - 0.02 – 0.14) for a unit increase in volume group (OR = 1.06; 95% CI; 0.98 – 1.15)


Katz (2004) The United States of America

Those patients who were treated at hospitals that performed ≥200 procedures compared to those who performed <25 had a lower risk of pneumonia (OR 0.65, 99% CI; 0.47 -0.90) Patients who were treated by the highest volume category surgeons had a lower complication rate than those treated by the lowest volume surgeons, (2.9% versus 4.0%; OR 0.81, 99% CI, 0.68 to 0.98, p=0.003). Those patients who were treated at hospitals that performed ≥200 procedures compared to those who performed <25 had a lower risk of adverse events including: death, pneumonia, pulmonary embolus, acute myocardial infarction, and deep infection (OR 0.74, 99% CI; 0.60 -0.90) Those patients who were treated by surgeons who performed >50 procedures compared to those who performed <12 had a lower risk of pneumonia (OR 0.72, 99% CI; 0.54-0.95), as well as a lower risk for other adverse events (OR 0.81 99% CI,)


Kreder (2003) Canada

Patients treated in hospitals that performed <48 procedures had a 2.2 fold greater 1 year revision rate in comparison to patients treated in hospitals performing >113 procedures per year. Patients treated by surgeons performing <14 procedures per year stayed and average of 1.4 days (95% CI; 1.2-1.9) longer than patients treated in hospitals performing >42 procedures per year. Patients treated by hospitals performing <48 procedures per year stayed and average of 0.8 days (95% CI; 0.5-1.1) longer than patients treated in hospitals performing >113 procedures per year. Patients treated by surgeons performing between 48-113 procedures per year stayed and average of 0.4 days (95% CI; 0.2-0.6) longer than patients treated in hospitals performing >113 procedures per year. There was no significant association between surgeon volume and mortality at 3 months. There was no significant association between hospital volume and mortality at 3 months. There was no relation between surgeon volume and readmission rates for knee infection at 3 years. There was no relation between hospital volume and readmission rates for knee infection at 3 years. Surgeon volume was not significantly associated with increased complication rates.



Mean length of stay was significantly shorter for high volume hospitals than low 39.24±18.09 vs. 54.44±26.60 (P<0.001) High-volume groups rather than low volume groups had a significantly shorter pre-operative stay for patients receiving TKA [6.47±9.35 vs 10.00±13.72 (P<0.001)]and Non Osteo-arthritis patients receiving TKA [7.28±12.24 vs. 14.08±21.37(P=0.01)] Mean postoperative length of stay was significantly less for high volume patients than low volume patients who received, TKA [32.77±13.15 vs. 44.45±17.83 (P<0.001)], TKA with Oesto-arthritis [33.18±11.25 vs. 42.65±13.34 (P<0.001)], TKA and Non Osteo-arthritis[32.14±15.64 vs. 49.47±26.13 (P<0.001)]. The total mean length of stay for high volume groups was less than low volume groups 15.46 days The preoperative length of stay for high volume groups was less than low volume groups 3.70 days The postoperative length of stay was shorter for high volume groups than low volume groups11.76 days


Norton (1998) The United States of America

The probability model implies that an increase in operations from 40 to 80 would reduce the likely complication rate by 3 percentage points.


Solomon (2006) Atlanta, The United States of America

Hospital-related outcomes LHV associated with increased risk of an adverse postoperative event (OR: 1.8, 95%CI: 1.2-2.6) compared to HVH Controlling for patient characteristics: LVH associated with adverse postoperative events (OR: 1.8, 95%CI: 1.2-2.8) compared to HVH Controlling for patient characteristics and hospital survey responses: LVH associated with adverse postoperative events (OR: 1.6, 95%CI: 1.1-2.5) compared to HVH


SooHoo (2006) California The United States of America

Hospital-related outcomes 90-day outcomes (compared to HVH): LVH had higher mortality rate (0.55% vs. 0.49%, OR: 1.50, 95%CI: 1.14-1.98, p = 0.004) LVH had higher readmission rate for infection (1.13% vs. 0.65%, OR: 1.60, 95%CI: 1.21-2.12, p = 0.001) LVH had higher readmission rate for pulmonary embolism (0.48% vs. 0.39%, OR: 1.45, 95%CI: 1.07-1.97, p = 0.016) LVH had higher readmission rate for thrombophlebitis (0.49% vs. 0.28%, OR: 2.12, 95%CI: 1.47-3.05, p ≤ 0.001) LVH had higher combined rate of death or readmission for any cause (14.28% vs. 11.97%, OR: 1.50, 95%CI: 1.14-1.98, p = 0.004) MVM had higher mortality rate (0.59% vs. 0.49%, OR: 1.31, 95%CI: 1.09-1.58, p = 0.003) MVH had higher combined rate of death or readmission for any cause (13.38% vs. 11.97%, OR: 1.31, 95%CI: 1.09-1.58, p = 0.003) 1-year outcomes (compared to HVH): LVH had higher mortality rate (OR: 1.19, 95%CI: 1.01-1.41, p = 0.035) LVH had higher readmission rate for infection (OR: 1.64, 95%CI: 1.28-2.09, p ≤ 0.001) LVH had higher readmission rate for pulmonary embolism (OR: 1.27, 95%CI: 1.03-1.56, p = 0.027) LVH had higher readmission rate for thrombophlebitis (OR: 1.98, 95%CI: 1.46-2.68, p ≤ 0.001) LVH had higher combined rate of death or readmission for any cause (OR: 1.22, 95%CI: 1.12-1.32, p ≤ 0.001) MVM had higher mortality rate (OR: 1.18, 95%CI: 1.06-1.32, p = 0.002) MVM had higher readmission rate for pulmonary embolism (OR: 1.16, 95%CI: 1.02-1.33, p = 0.029) MVH had higher combined rate of death or readmission for any cause (OR: 1.12, 95%CI: 1.05-1.19, p ≤ 0.001)


Taylor (1997) The United States of America

Hospital-related outcomes Total knee arthroplasty procedures: No significant difference between LVH and MVH in-house mortality rates (0.35% vs. 0.27%, n.s.) MVH had significantly higher in-house mortality rate than HVH (0.27% vs. 0.22%, p < 0.02) Knee revision procedures: Mortality rates similar to total knee arthroplasty were reported for knee revision, however due to the small sample size statistical significance could not be tested.

Appendix C 2.3: Financial Data – Knee Authors Financial data


Mean charges

High Volume Low Volume P Value Total Knee Arthroplasty 2,021,540.31±415,919.82 1,981,238.99±825,042.30 P= 0.45 Osteoarthritis 2,038,785.52±288,4445.78 1,950,559.51 ±758,607.43 P= 0.12 Non- Osteoarthritis 1,995,001.83±557,881.57 2,066,973.42±988,262.17 P= 0.56

Factors related to costs

Patient Factor Total Charge (Yen) Patient volume 45,484.33 Age 5121.93 Sex -794.97 Comorbidity 105,240.00* Transfer to hospital 111580.00 Diagnosis (OA, Non OA) -44,449.89 Adjusted 0.01 F value 1.88

* P< 0.05


STUDY DESIGN TABLES

Appendix C 3.1: Study design tables – Liver Resection Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria

Begg (1998) The United States of America



Age: %

Age Low Medium High 65 – 69 40 35 47 70 – 74 27 37 30 ≥75 33 28 22

Hospital Number: Hn = NR Based on total number of procedures performed during study period Surgeon Number: Sn = NA Volume Definitions: Hospital:

Low Medium High 1 - 5 6 - 10 ≥11

Surgeon: NA

Level of Evidence: III-3 Follow-up: 30 days Lost to Follow-up: NR Study Period: 1984 – 1993 Inclusive Outcome Measures: 30-day mortality Data Source: Surveillance, Epidemiology and End Results (SEERS) – Medicare linked database

Condition: Liver Metastases following cancer of the colon and rectum Procedure: Partial Hepatectomy Lobectomy of the liver ICD- 9 Classification: ICD 9 - CM Partial Hepatectomy 50.22 Hepatic Lobectomy 50.3, 50.4 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: 65 - 69, 70 - 74, ≥75 Race: NR Comorbidities: See Table 1: Volume and Comorbidity Cancer type: Primary cancer of the colon-rectum

Inclusion criteria: Patients >65 years old. Exclusion criteria: NR

Appendix C 3.1: Study design tables – Liver Resection (Continued) Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria

Begg (1998) (Cont.) The United States of America


Hospital Volume Number of Procedures n(%)

1 138(4) 2 106(9) 3 108 (5) 4 60 (7) 5 70 (4) 6 36 (2) 7 49 (4) 8 40 (3) 10 20 (5) 11 11 (9) 12 12 (0) 13 13 (8) 16 32 (0) 18 18 (0) 20 20 (0) 21 21 (0) 23 23 (0) 24 24 (4)

Length of stay: NR

Cancer Stage: NR Treatment Type: NR

Appendix C 3.1: Study design tables – Liver Resection (Continued)

Table 36: Volume and Comorbidity (Begg 1998).

Comorbidity index, % (Charlson/ Romano) Procedure Volume No. of patients 0 1 2

Hepatic Resection 1 – 5 Low 482 80 17 2 6 – 10 Medium 145 81 17 2 ≥11 Hih 174 88 10 2


Choti (1998) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 606 (Minor = 374, Major = 232)

Low High 342 264

Age: Mean

Low High 55.4 54.3

P= 0.45 Hospital Number: Hn =36


Surgeon Number: Sn = NA Volume Definitions: Hospital: Discharges

Low High ≤15 >15

Relative Risk of Mortality

Low Medium High <7 7 – 15 >15

Surgeon: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 01/01/1990 – 30/06/1996 Outcome Measures: Length of Stay Average total hospital charges In-hospital mortality Data Source: Maryland Health services Cost Review Commission

Condition: (ICD – 9) Primary liver Cancer 155.0, 155.2 Metastatic Cancer 153.0, 153.9, 154.0, 157.0, 157.4. 197.0, 197.7 Liver resection from trauma, Benign neoplasms Infectious Processes Procedure: Partial Hepatectomy (Minor Resection) Hepatic Lobectomy (Major Resection) ICD- 9 Classification: ICD - 9 Partial Hepatectomy 50.22 Hepatic Lobectomy 50.3 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Mean

Low High 55.4 54.3

P= 0.45

Inclusion criteria: Primary liver Cancer 155.0, 155.2 Metastatic Cancer 153.0, 153.9, 154.0, 157.0, 157.4. 197.0, 197.7 Liver resection from trauma, Benign neoplasms Infectious Processes Exclusion criteria: Cryosurgery and other nonresectional therapy

Appendix C 3.1 Study design tables – Liver Resection (Continued) Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria

Choti (1998) (Cont.) The United States of America

End Points: Morbidity: NR Mortality: %

Low High Primary cancer 18.8 4.9

Hepatic resection for primary liver cancer was associated with a significantly higher mortality (P <0.01) compared to metastatic cancer. Over all mortality rate was 11.0% for primary cancer compared to 2.8% for those undergoing resection for metastatic cancer. Mortality: Overall See Table 37: Unadjusted Mortality; Table 38: Adjusted relative risk of mortality Table 39: Association of Hospital volume and in-hospital mortality Length of stay: Unadjusted Average

Category Low Volume High Volume P Value All procedures 13.2 12.7 0.15 Partial Hepatectomy

10.8 11.7 <0.01

Hepatic Lobectomy

16.6

14.9 0.98

Diagnosis Primary liver Cancer

15.4 14.8 0.09

Metastatic Cancer 11.4 11.6 0.88 All other diagnoses

14.6 13.0 0.63

Sex:

Sex Low High Male 54.4 50.4 Female 45.6 49.6

Race: %

Race Low High White 67.3 82.2 Afro-American

27.5 12.1

Other 5.3 5.7 P=<0.01 Comorbidities: %

Low High 0 69.6 72.0 1 25.7 23.9 ≥2 4.7 4.2

Dartmouth Manitoba adaptation of Charlson Comorbidity index Cancer type: Primary liver cancer 109 Metastatic cancer 285 Other diagnosis 212 Treatment Type: n(%) Partial Hepatectomy 374 (62) Hepatic Lobectomy 232 (38)


Choti (1998) (Cont.) The United States of America

Adjusted Average

Category Low Volume High Volume P Value All procedures 9.8 11.1 0.02 Partial Hepatectomy

8.4 10.4 <0.01

Hepatic Lobectomy

11.9 12.6 0.56

Diagnosis Primary liver Cancer

10.9 13.3 0.15

Metastatic Cancer 9.5 10.1 0.31 All other diagnoses

9.8 10.8 0.39

Hepatic resection for primary liver cancer was associated with a significantly longer length of stay (P <0.01) compared to metastatic cancer. The average length of stay for primary cancer was 15.1 days compared to 11.5 days for patients undergoing resection for metastatic cancer

Table 37: Unadjusted Mortality (Choti 1998).

Mortality Relative risk of mortality Category Low Volume High Volume Low vs. High Volume P Value All procedures 7.9 1.5 5.21 <0.01 Partial Hepatectomy 6.1 1.1 5.33 0.03 Hepatic Lobectomy 10.4 2.3 4.58 0.04 Diagnosis Primary liver cancer 18.8 4.9 3.81 0.05 Metastatic cancer 5.0 0.0 >5.00 NS All other diagnoses 7.5 1.3 5.82 0.09

Appendix C 3.1 Study design tables – Liver Resection (Continued)

Table 38: Adjusted relative risk of mortality (Choti 1998)

Relative risk of mortality Category Low vs. High Volume P Value All procedures 5.20 <0.01 Partial Hepatectomy 5.25 0.03 Hepatic Lobectomy 4.37 0.05 Diagnosis Primary liver cancer 2.88 0.14 Metastatic cancer >5.00 NS All other diagnoses 5.92 0.99

Table 39: Association of Hospital volume and in-hospital mortality

Hospital volume No. of hospitals Total cases Deaths Mortality rate (%) Adjusted relative risk P Value ≤7 33 209 20 9.6 6.4 <0.01 7 – 15 2 133 7 5.3 3.4 0.05 >15 1 264 4 1.5 1.0 NA



Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume Population Number: n(%) Pn = 569 Age: Mean (SD)

Without daily ICU physician With daily ICU physician 58 (16) 56 (16)

Hospital Number: Hn = 31 High volume hospitals n=3 Surgeon Number: Sn = 114 High volume surgeons n=11 Volume Definitions: Hospital: NR Surgeon: NR End Points: Morbidity: See Table 40: Postoperative Complications Mortality: Cardiac complications OR 3.8; 95% CI 1.4 – 10.8 Surgical complication OR 4.7; 95% CI 1.9 – 11.8 Reintubation OR 18.3; 95% CI 7.7 – 43.3 Pulmonary insufficiency OR 5.7 95% CI 1.8 – 18.2 Septicemia OR 5.5; 95% CI 1.5 – 20.6 Acute renal failure OR 55.5; 95% CI 15.4 – 200

Level of Evidence: III-2 Follow-up: NR Lost to Follow-up: NR Study Period: 1994 - 1998 Outcome Measures: In-hospital mortality Hospital length of stay Health care costs Data Source: Uniform Data Discharge set maintained by the Health Services Cost Review Commission (HSCRC) ICU director questionnaire response Response rate Total: 85% (39 of 46) Hepatic resection ICUs : 78% (25 of 32)

Condition: See Table 6: Patient Condition Procedure: Hepatic Wedge Resection Hepatic Lobectomy ICD- 9 Classification: ICD9 - CM Partial Hepatectomy 50.22 Hepatic Lobectomy 50.3 Training Hospital: NR Institutional/Environmental Support: Selective Referral: NR Covariates: Age:

Without daily ICU physician

With daily ICU physician

58 (16) 56 (16) Sex: male



56 50 Race: White



67 83

Inclusion criteria: Hospitals must have performed more than 30 procedures over the study period. Surgeons must have performed more than 10 procedures over the study period Exclusion criteria: Patients less than 18 years old.

Appendix C 3 .1: Study design tables – Liver Resection (Continued) Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria


Multivariate analysis of in-hospital mortality

Patient characteristics Hospital length of stay (95% CI) Age 1.0 (0.99 – 10.2) Male Sex 1.5 (0.8 – 3.2) Nonwhite 1.2 (0.4 – 3.7) Hepatic Lobectomy 3.3 (1.2 – 9.4) Urgent admission 0.9 (0.1 – 9.0) Emergent admission 0.4 (0.1 – 1.3) Hospital Characteristics Without daily rounds 3.8 (1.4 – 10.2) Low hospital volume 1.4 (0.6 – 3.2) Low surgeon volume 1.2 (0.6 – 2.4)

Length of stay: Multivariate analysis for length of stay

Patient characteristics Hospital length of stay (95% CI) Age % (0 – 1%) Male Sex 12% (4 – 20%) Nonwhite 10% (0 – 18%) Hepatic Lobectomy 18% (7 – 28%) Urgent admission 36% (19 – 55%) Emergent admission 35% (2 – 79%) Hospital Characteristics Without daily rounds 7% (-8 – 20%) Low hospital volume 21% (2 – 44%) Low surgeon volume -1% (-9 – 7%)

Univariate analysis did not show any difference between high and low volume hospitals 7 days (IQR = 6 – 11) and 7 days (IQR = 6 – 11) respectively.

Comorbidities:

Comorbidities % Without ICU Physician

With ICU Physician

Metastases 57 59 Malignancy 26 28 Mild to moderate diabetes

12 12

Mild liver disease

8 8

Chronic Pulmonary Disease

5 2

Myocardial infarction

1 5

Moderate to severe liver disease

3 4

Peripheral vascular disease

2 2

Renal disease 3 0.4 Diabetes with complications

2 0.4

Dementia 0 0.4 Cerebrovascular disease

0.4 0



Factors in multivariate analysis, incorporating patient characteristics, demonstrating increase in hospital stay Low volume hospitals 21% (95% CI 2 – 44%; p = 0.03) Urgent admission 36% (95% CI 19 - 55%; p <0.001) Emergent admission 35% (95% CI 2 - 79%; p = 0.04) Hepatic Lobectomy 18% (95% CI 7 – 28%; p = 0.01) Male Gender 12% (95% CI 4 – 20%; p = 0.01) Non-white 10% (95% CI 0 – 18%; p = 0.04)

Other:

Complications ICD-9-CM Aspiration 507

9973 Pulmonary insufficiency

5184 5185 5188

Cardiac Complications

9971

Pneumonia 480-487 Acute renal failure 584 Septicemia 038 Post operative infection

9985

Cardiac arrest 4275 Acute myocardial infarction

410

Reintubation 9604 Re-operation for bleeding

3941 3949 3998

Post operative complications

9981-9983

Nature of admission: (%)

Without ICU Physician

With ICU Physician

Elective 77 83 Urgent 2 11 Admission 16 6



Cancer Type: Primary diagnosis


With ICU Physician

Secondary malignancy

53 60

Primary hepatic malignancy

14 16

Primary biliary malignancy

4 5

Benign liver malignancy

12 7

Traumatic liver injury

10 4

Other benign liver disease

7 8

Treatment Type:


With ICU Physician

Hepatic wedge resection

54 64

Hepatic lobectomy

46 36

Appendix C 3 .1: Study design tables – Liver Resection (Continued)

Table 40: postoperative complications

Complication No daily rounds by an ICU physician daily rounds by an ICU physician Odds Ratios (95% CI) P Aspiration 11 10 1.1 (0.6-1.9) 0.3 Reintubation 11 1 16.2 (3.8-67) <0.0011 Surgical complications 9 5 1.7 (0.9-3.4) 0.1 Pulmonary insufficiency 6 1 8.0 (1.8-35.0) 0.006 Pneumonia 5 1.5 3.7 (1.2-11.3) 0.02 Cardiac arrest 0.4 0.4 1.0 (0.1-16.2) 0.99 Acute myocardial infarction 1 0 - - Cardiac complications 4 8 0.5 (0.2-1.1) 0.08 Septicemia 3 2 1.2 (0.4-3.6) 0.8 Post operative infection 3 3 0.8 (0.3-2.2) 0.6 Acute renal failure 3 0.4 9.3 (1.2-74) 0.04


Dimick (2003) The United States of America It is likely that this review contains sections of the same patient cohort as reported in Dimick (2002)


Low High Totals* 275 276 551 147 442 589

*Three different population totals were reported in this review Partial Hepatectomy n=338 Hepatic Lobectomy n=231

Low High 59±16 56±15


Low High 32 3


Low High No. of hospitals 32 3 No. of operations 147 422

Surgeon: NA End Points: Morbidity:

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1994 - 1998 Outcome Measures: Ion-hospital Mortality Length of stay Health care costs Data Source: State discharge database maintained by the Health Services Cost Review Commission (HSCRC) of Maryland

Condition: NR Procedure: Partial Hepatectomy Hepatic Lobectomy Hepatic Wedge Resection ICD- 9 Classification: ICD – 9 - CM Partial Hepatectomy 50.22 Hepatic Lobectomy 50.3 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: n=589

Low High 59±16 56±15

Sex: n=589 Male (%)

Low High 51 52

Race: n=589 White (%)

Low High 65 78



Dimick (2003) (Cont.) The United States of America It is likely that this review contains sections of the same patient cohort as reported in Dimick (2002)

Mortality:

All patients (n=569)%

Low volume hospitals (n=276)%

High volume hospitals (n=275)%

P value

In-hospital mortality

4.8 10.2 2.8 <0.001

Adjusted for casemix

Independent Variable Risk of in-hospital mortality (OR, 95%CI)

P value

Low-volume hospital 3.1 (1.3 – 7.6) 0.02 Age 1.0 (0.98 – 1.05) 0.2 Male 1.0 (0.4 – 2.5) 0.07 Non-white 1.3 (0.5- 3.3) 0.5 Hepatic lobectomy* 2.2 (0.9 – 5.7) 0.09 Urgent/Emergent** 2.1 (00.8 – 5.9) 0.14 Chronic renal disease 24 (5.3 - 111) <0.001 Liver disease 7.0 (1.6 – 30.4) 0.009

*Associated risk in comparison to hepatic wedge resection ** Associated risk in comparison to elective admission

Extent of resection Partial Lobectomy P value Mortality 3.0 7.4 P= 0.02

Trend towards significance for extent of resection: OR 2.2; 95% CI. 0.9 – 5.7; P=0.09 Trend towards significance for Urgent/Emergent compared to Elective admission: OR 2.1; 95% CI. 0.8 – 5.9; P=0.10 See Tables 40 - 42 Length of stay:

All patients (n=569)

Low volume hospitals (n=276)

High volume hospitals (n=275)

P value

Length of stay, median, IQR

7 (2-9) 7 (6-11) 7(6-11) 0.9

Comorbidities: See Table 43: Patient comorbidities Other:

Complication ICD-9-CM Aspiration 507

9973 Pulmonary insufficiency

5184 5185 5188

Cardiac Complications

9971

Pneumonia 480-487 Acute renal failure 584 Septicemia 038 Post operative infection

9985

Cardiac arrest 4275 Acute myocardial infarction

410

Reintubation 9604 Re-operation for bleeding

3941 3949 3998

Post operative complications

9981-9983

Urgent or emergent admission: % LVH:30 HVH:16 P<0.05


Dimick (2003) (Cont.) The United States of America It is likely that this review contains sections of the same patient cohort as reported in Dimick (2002)

Cancer type: NR Treatment Type: Partial Hepatectomy n=338 (59%) Hepatic Lobectomy n=231 (41%)

Table 41: Comorbid diseases associated with and increased rate of in-hospital mortality (Univariate analyses)

Comorbidities P value Peripheral vascular disease (P=0.07) Mild liver disease (P=0.05) Moderate/severe liver disease (P<0.001) Chronic renal disease (P<0.001) Diabetes with complications (P=0.003) History of Myocardial infarction (P=0.14)

Table 42: Comorbid diseases associated with increased rate of in-hospital mortality (Multivariate analyses)

Comorbidities Odds ratios Chronic renal disease 24; 95% CI; 5.3 – 111; P<0.001 Pre-existing liver disease 7.0; 95% CI;1.6 – 30.4; P=0.009


Table 43: Effect of Hospital volume on In-hospital mortality after adjusting for case-mix and postoperative complications

Independent Variable Risk of in-hospital mortality adjusted odds ratio (95% CI) P value Low-volume hospital 2.1 (0.6 -5.2) 0.22 Pulmonary complications 12.8 (3.6 – 46.0) 0.001 Acute renal failure 16.1 (1.9 - 138) 0.01

Table 44: Patient comorbidities

Comorbid disease state (%) Low volume hospital High volume hospital Metastases from solid tumour 53.1 60.0 Malignancy 34.0 25.1 Mild to moderated diabetes 12.9 12.6 Diabetes with complications 2.0 1.0 Mild liver disease 10.9 7.3 Chronic pulmonary disease 5.4 3.3 History of Myocardial infarction 2.0 3.0 Moderate to severe liver disease 2.7 3.3 Peripheral vascular disease 3.4 1.9 Renal disease 3.4 1.2

Table 45: Specific complications and relative risk, based on Univariate analysis

Comorbidities Relative Risk Cardiac complications 3.6; 95% CI, 1.4 – 8.8; P= 0.005 Surgical complications 4.5; 95% CI, 2.0 – 10.0; P<0.001 Reintubation 13.4; 95% CI, 6.9 – 26.2; P<0.001 Pulmonary failure 5.0; 95% CI, 1.9 – 13.1; P= 0.001 Septicemia 5.3; 95% CI, 1.8 – 15.5; P= 0.002 Pneumonia 3.4; 95% CI, 1.1 – 10.4; P= 0.03 Acute renal failure 23.5; 95% CI, 13.7 – 40.4; P<0.001 Acute myocardial infarction 7.2; 95% CI, 1.4 – 37.5; P= 0.02


Table 46: Variation in post-operative complications

Complications Overall incidence % Range of incidence Low % to High % Extremal ratio Aspiration 10.1 4.8 – 10.1 2.10 Reintubation 5.6 0.4 – 11.9 29.8 Surgical complications 7.2 4.9 – 23.8 4.9 Pulmonary insufficiency 3.3 0.8 – 9.5 11.8 Pneumonia 3.5 1.5 – 15.0 10.0 Acute myocardial infarction 0.5 0 – 1.6 … Cardiac complications 5.9 3.3 – 15.0 4.5 Septicemia 2.3 0 – 10.0 … Post operative infection 3.0 0 – 4.8 … Acute renal failure 1.8 0.4 – 5.0 12.5

Table 47: Univariate relative risk of post-operative complications

Complications High volume hospital (patients n=422)

Low volume hospital (patients n=147)

Relative Risk (95% CI)

P value

Aspiration 9.0 13.6 1.4 (0.9 – 2.0) 0.11 Reintubation 3.1 12.9 2.5 (1.8 – 3.4) <0.001 Surgical complications 6.4 9.5 1.5 (0.8 – 2.7) 0.2 Pulmonary insufficiency 1.9 7.5 2.3 (1.6 – 3.5) 0.001 Pneumonia 2.6 6.1 2.4 (1.0 – 5.6) 0.05 Acute myocardial infarction 0.2 1.4 2.6 (1.2 – 5.9) 0.1 Cardiac complications 6.4 5.0 0.8 (0.3 – 1.7) 0.5 Septicemia 2.1 2.7 1.3 (0.4 – 3.6) 0.7 Post operative infection 3.1 2.7 0.88 (0.3 – 2.4) 0.8 Acute renal failure 1.2 3.4 2.0 (1.1 – 3.7) 0.07


Dimick (2003b) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =2097 (Minor = 1164, Major = 933) LVH: 1086 (52) HVH: 1011 (48) Age: LVH: 57±19 HVH: 54±17 Hospital Number: Hn = 472 1996: 221 1997:251 Surgeon Number: Sn = NA Volume Definitions: Hospital:

Definition 1996 n 1997 n LVH 1-9/year 201 226 HVH ≥10/year 20 25

Surgeon: NA End Points: Morbidity: NR Mortality: Over all mortality 5.8% HVH (3.9%) vs. LVH (7.6%); P<0.001 RR 0.51 95% CI 0.34-0.73

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1996-1997 Outcome Measures: In-hospital mortality Length of stay Data Source: Nationwide In-patient Sample (NIS)

Condition: Primary hepatic malignancy, secondary malignancy, benign hepatic neoplasm, biliary malignancy, benign hepatic disease, traumatic liver laceration or other. Procedure: Hepatic Wedge resection Hepatic Lobe resection ICD- 9 Classification: ICD-9-CM Hepatic Wedge resection: 5022 Hepatic Lobe resection: 503 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: LVH: 57±19 HVH: 54±17 Race: Not white LVH: 214 (20) HVH: 154 (15)

Inclusion criteria: Patients with ICD-9-CM codes (5022, 503) plus undergoing resection for laceration, however the latter were excluded from multivariate analysis. Exclusion criteria: Patients who underwent Percutaneous (5011), or Open wedge resection (5012). Patients with traumatic liver resection (5061, 5069)


Dimick (2003b) (Cont.) The United States of America

Increased mortality with age OR 1.01; 95% CI 1.00-1.02; P=0.03 <65 years HVH 3.5% vs. LVH 5.9% (P=0.04) >65 years HVH 4.7% vs. LVH 10.1% (P=0.006) Mortality and nature of presentation (%) Elective: 4.1 Urgent: 7.5 Emergent: 12.9 P< 0.001 Mortality and sex (%) Female: 7.2 Male:4.6 P=0.01 Mortality and extent of resection (%) Hepatic lobectomy: 7.6 Hepatic wedge resection: 4.4 P= 0.002 Other Univariate risk factors which increase risk of morality: Race: P=0.001 Chronic Obstructive Pulmonary Disease: P<0.001 Metastatic Disease: P<0.001 History of mild liver disease: P=0.001 History of moderate to severe liver disease: P<0.001 See Table 15: Mortality rate according to indication for hepatic resection Table 16: Variables associated with in-hospital mortality Length of stay: Overall length of stay was 7 days (median) HVH vs. LVH: 7 days[IQR, 5-9] vs. 8 days [IQR, 5-11]; P=0.002 Lobectomy vs. wedge resection: 7 days [IQR, 5-9] vs. 8 days [IQR, 6-12]; P<0.001 >65 years vs. <65 years: 7 days [IQR, 5-10] vs. 8 days [IQR, 6-11]; P<0.001

Sex: Female LVH: 562 (52) HVH: 529 (52) Comorbidities: See Table 50: Comorbid characteristics Cancer Type: See Table 51: Indications for liver resection Treatment Type: n (%)

LVH HVH Elective admission

628 (58) 780(77)

Urgent admission

97 (9) 67 (7)

Emergent admission

159 (15) 97 (10)

Hepatic Lobectomy: n (%) LVH: 452 (42) HVH: 481 (48) Malignancy: n (%) LVH: 281 (28) HVH: 402 (37)


Dimick (2003b) (Cont.) The United States of America

Other Univariate risk factors which increase length of stay: Female sex: P<0.001 Urgent admission: P<0.001 Emergent admission: P<0.001 Malignancy: P<0.001 Metastatic disease: P=0.02 Chronic pulmonary disease: P=0.02 Sever liver disease: P<0.001 In addition, respective to other resection for metastases all other indications for surgery had a Univariate association with LOS of P<0.05 See Table 48: Variables associated with in-hospital length of stay

Table 48: Mortality rate (%) according to indication for hepatic resection

Indication for Surgery High Volume Hospital Low Volume Hospital Metastatic Disease 2.6 4.9* Primary hepatic malignancy 6.3 15.5* Benign hepatic neoplasm 0.9 0.0 Biliary tract malignancy 0.0 3.2 Benign hepatic disease 0.0 5.1 Benign biliary disease 0.0 2.4 Traumatic laceration 30.0 26.5 *Comparison of high and low volume hospitals; P<0.05 X² test

Table 49: Variables associated with in-hospital mortality

Independent Variable Risk of In-hospital mortality (OR 95% CI) P value High volume hospital 0.6 (0.4-0.9) 0.02 Mild to moderate liver disease 2.0 (1.0-3.8) 0.04 Hepatic Lobectomy 2.2 (1.4-3.3) <0.001 Age older than 65 years 2.2 (1.4-3.2) 0.001 Chronic pulmonary disease 2.7 (1.3-5.7) 0.007 Primary hepatic malignancy 3.0 (1.7-5.2) <0.001 Severe liver disease 72.0 (23.7-218.5) <0.001


Table 50: Variables associated with in-hospital length of stay

Independent Variable Adjusted % rate increase for length of stay (OR 95% CI) P value High volume hospital -5 (-9-1) 0.09 Age older than 65 years 9 (3-15) 0.01 Female sex 10 (5 to 15) <0.001 Biliary malignancy 20 (2.3 to 41) 0.03 Hepatic Lobectomy 21 (15-28) <0.001 Urgent admission 24 (13-36) <0.001 Benign hepatic disease 27 (3.1-57) 0.02 Emergent admission 51 (37-67) <0.001 Severe liver disease 116(66-182) <0.001

Table 51: Comorbid characteristics

Characteristics High Volume Hospital n(%) Low Volume Hospital n(%) Diabetes mellitus 90(9) 105 (10) Mild to moderate liver disease 75 (7) 86 (8) Chronic obstructive pulmonary disease 23 (2) 58 (5) History of myocardial infarction 24 (2) 11 (1) Severe liver disease 8(<1) 13 (1) Chronic Renal disease 2 (<1) 3 (<1)

Table 52: Indications for liver resection

Indication for Surgery High Volume Hospital n(%) Low Volume Hospital n(%) Metastatic Disease 537 (54.7) 553 (51.2) Primary hepatic malignancy 161 (16.4) 168 (15.6) Benign hepatic neoplasm 110 (11.2) 89 (8.2) Biliary tract malignancy 38 (3.7) 62 (5.7) Benign hepatic disease 25 (2.6) 39 (3.6) Benign biliary disease 15 (1.5) 42 (3.9) Traumatic laceration 38 (3.9) 87 (8.0) Other 58 (5.9) 41 (3.7)


Dimick (2004) The United States of America This study likely contains a sub-group analysis of patients reported in Dimick (2003b)

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =16 582 (Minor = 10 690, Major = 5 892) Age:

Overall Period 1 Period 2 Period 3 57±16 57±17 57±17 58±16

Hospital Number: Hn =8 141

Definition Period 1 Period 2 Period 3 LVH 1-9 NR NR NR HVH ≥10 1 494 2 435 4 212

1988/1989, 37% of resection performed in HVH, 1999/2000, 57%; P<0.001 Surgeon Number: Sn =NA Volume Definitions: Hospital:

Definition LVH 1-9/year HVH ≥10/year


Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1988-2000 Outcome Measures: In-hospital mortality Length of stay Time trends for these outcomes were also determined for the periods: Period 1: 1988 - 1991 Period 2: 1992 - 1995 Period 3: 1996 - 2000 Data Source: Nationwide In-patient Sample (NIS)

Condition: See Table 55: Indications for hepatic resection Procedure: Lobe resection Wedge resection ICD- 9 Classification: ICD-9-CM Lobe resection 503 Wedge resection 5022 Training Hospital: n(%)

HVH* Overall 10 290 (68) Period 1 1 718 (58) Period 2 3 127 (65) Period 3 5 445 (74)

*LVH: NR The majority of hepatic resections were performed in teaching hospitals, increase across periods; Period 1= 58%, Period 2= 74% P<0.001 Institutional/Environmental Support: NR Selective Referral: NR Covariates:

Inclusion criteria: All patients discharged during the study duration with the ICD-9-CM codes 503 and 5022 were included in this study. Exclusion criteria: NR



Mortality: Overall mortality: 7.4% Metastatic tumours vs. primary hepatic malignancy: 4.2 vs. 11.2 (P<0.001) Hepatic lobe resection vs. Hepatic wedge resection: 9.4 vs.6.3 (P<0.001) Period 3 Hepatic lobe resection vs. Hepatic wedge resection: 8.1 vs. 4.5 (P<0.001) Study duration and mortality

1988/99 1990/91 1992/93 1994/95 1996/97 1998/2000 Mortality %

10.4 9.1 8.7 7.0 6.5 5.3

Multivariate analysis for hospital and patient characteristics Period 1 increase: 37% (95% CI, 16% to 62%; P<0.001) Period 2 increase: 31% (95% CI, 10 to 55%; P=0.002) Length of stay: (Mean), [SD], {Range} Median length of stay: 11 days (1988/89) vs. 7 days (1999/2000); P<0.001 During 1988/89 27% of patients had a prolonged length of stay vs. 13% in 1999/2000; P<0.001 Adjustment analyses for hospital and patient characteristics compared to period 1 Period 2: 29% (95% CI, 11% to 49%; P=0.001) Period 3: 77% (95% CI, 54 % to 104%; P<0.001)

Age:

HVH* Overall 57±16 Period 1 57±17 Period 2 57±17 Period 3 58±16

*LVH: NR Race: Non-Caucasian n(%)

HVH* Overall 2 322 (14) Period 1 286 (7) Period 2 758 (15) Period 3 1 278 (17)

*LVH: NR Sex: Female Gender n(%)

HVH* Overall 8 861 (52) Period 1 2 126 (53) Period 2 2 662 (51) Period 3 3 858 (51)

*LVH: NR Comorbidities: See Table 56: Patient comorbid characteristics Cancer type: See Table 55: Indications for hepatic resection

Appendix C .31: Study design tables – Liver Resection (Continued) Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria


Admission Type: HVH n(%)

Urgent admission

Emergent admission

Overall 2 243 (15) 2 659 (18) Period 1 693 (17) 810 (20) Period 2 760 (15) 824 (16) Period 3 790 (11) 1 025 (14)

*LVH: NR

Table 53: Indications for hepatic resection

Period 1 Period 2 Period3 Secondary metastases 2 026 (51) 2 797 (54) 4 177 (56) Primary hepatic malignancy 423 (11) 604 (12) 862 (12) Primary biliary malignancy 199 (5) 266 (5) 387 (5) Benign hepatobiliary disease 584 (15) 743 (14) 1 007 (14) Traumatic laceration 531 (13)* 432 (8) 434 (6)* Other 186 (5) 254 (5) 351 (5) *P<0.001

Table 54: Patient comorbid characteristics

Number of comorbidities Overall Period 1 Period 2 Period3 0 4 073 (24) 1 207 (30) 1 283 (25) 1 583 (21) 1 6 338 (38) 1 460 (37) 2 002 (39) 2 876 (39) 2 5 046 (30) 1 051 (26) 1 581 (31) 2 414 (33) ≥3 1 125 (7) 272 (7) 297 (6) 546 (7)


Fong (2005) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =3734 (Minor = 2729, Major =1005)

Low volume High volume 3260 (88%) 474 (12%)

Primary 917 145 Metastatic 2343 329

Age: Total = 72±6

Low volume High volume 71±6 72±6


Low volume High volume 1272 12

Surgeon Number: Sn = NA Volume Definitions: Hospital: (Including surgery for benign disease)

Low volume High volume <25 >25


Level of Evidence: III-3 Follow-up: 5 years Lost to Follow-up: NR Study Period: 1995 and 1996 Outcome Measures: 30 day postoperative mortality Data Source: National Medicare Database

Condition: Primary malignancies of the liver and biliary tree: 1062 (28%) Metastatic disease of the liver: 2672 (72%) Procedure: Hepatic resection ICD- 9 Classification: NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Total = 72±6

Low volume High volume 71±6 72±6

P=NS Race: NR Sex:

Low High Total Male 1625 268 1893 Female 1635 206 1841

P=0.01

Inclusion criteria: Only liver resections for cancer Exclusion criteria: Resections for benign liver disease


Fong (2005) (Cont.) The United States of America

Mortality: Low volume centre: Mortality: 265/3037 (9%) High volume centre: Mortality: 21/474 (4%) Relative Risk of surgery at Low Volume Hospitals: 1.8 P Value: (P = 0.01) Length of stay: NR

Comorbidities:

Comorbidity ICD – 9 Diabetes 250.x Essential hypertension

401.x

Pulmonary disease

491.x, 492.x, 493.x, 495.x, 507.x, 511.x, 514.x, 514.x, 518.x

Renal disease 584.x, 591.x 593.x, 596.x

Cardiac disease 396.x, 402.x, 410.x, 412.x, 413.x, 414.x, 415.x, 424.x, 426.x, 427.x, 428.x, 429.x

Cancer type: See table 57: Cancer type Treatment Type: See Table 58: Extent of resection

Table 55: Cancer type

Cancer type Low volume High volume Total Primary 917 145 1062 Metastatic 2343 474 2817* *Two totals were reported by the author for this outcome 2817 and 2672


Table 56: Extent of resection

Low volume High volume Total <Lobectomy 2387 342 2729 Lobectomy or more 873 132 1005 P=NS

Table 57: Secondary diagnosis

Low volume High volume Total 0 1113 170 1283 1 1275 179 1454 2 673 99 772 3 177 23 200 4 22 3 25 Comorbidities Diabetes 434 62 496 Hypertension 860 129 989 Vascular 799 118 917 Renal 156 23 179 Cardiac 991 26 1117

Table 58: Predictors of outcome after hepatic resection (Multivariate analysis)

Relative risk P value Surgical volume 1.2 0.02 Gender 0.6 <0.001 Age 1.008 0.005 Renal 1.9 <0.001 Hypertension 0.8 <0.001 Pulmonary 1.1 NS Cardiac 1.2 0.002 Diabetes 1.1 NS Extent of procedure 1.0 NS


Gordon (1999) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =293 Age: Mean (SD) 57.4 (16.6) Hospital Number: Hn = NR Surgeon Number: Sn = NA Volume Definitions: Hospital: Procedures/year

Very low Low Medium High 10 11-20 21-50 >201


Overall Very low Low Medium High 10.2 21.2 19.4 7.4 4.6

Unadjusted Relative Risk

Overall Very low Low Medium High NA 4.7ns

(1.6-13.4) P<0.01

4.3ns (1.4-13.5) P<0.05

1.6ns (0.5-5.1)

1.0

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1990-1997 Financial Outcome Measures: Mortality Data Source: Maryland Health Services Cost Review Commission Database

Condition: NR Procedure: Hepatic Lobectomy ICD- 9 Classification: ICD-9-CM Hepatic Lobectomy 50.3 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: 57.4±16.6 Race: % Caucasian: 75.8 African American: 17.8 Sex: % Male: 52.9 Comorbidities: %

0 63.1 1 14.3 2 8.5 ≥3 14.0

Dartmouth-Manitoba adaptation of Charlson index

Inclusion criteria: This study examined six procedures. Patients included for hepatic Lobectomy had an ICD-9-CM code of 50.3 Exclusion criteria: Numerous non-complex surgical procedures were excluded, including: 41.5 Total splenectomy 43.7 distal gastrectomy with Jejunum anastomosis 44.31 to 44.39 gastroenterostomy 45.71 to 45.79 Distal large bowel excision 45.90 to 45.95 intestinal anastomosis 46.01 to46.04 exteriorization Of the bowel 46.10 to 46.14 colostomy 52.51 to 52.59 distal pancreatectomy



Adjusted Relative Risk

Overall Very low Low Medium High NA 4.7ns

(1.6-13.7) 3.8ns (1.2-12.4)

1.5ns (0.5-4.9)

1.0

Length of stay: NR

Cancer type: Benign: 21.5 Malignant: 78.5 Treatment Type: NR Type of admission: % Elective 62.5 Emergent/Urgent: 37.5


Glasgow (1999) The United States of America


Year No. of patients 1990 117 1991 95 1992 101 1993 87 1994 107

Number of procedures per 5 years n(%)

Low Medium High Very High 1 - 2 3 - 6 7 - 16 ≥17 115 (22.7) 130 (25.6) 116 (22.9) 146 (28.8)

Procedure Patient number Partial Hepatectomy 50.22 299 Hepatic Lobectomy 50.3 208

Age:

Age range No. (%) of patients <45 126 (24.8) 45-59 125 (24.6) 60-74 203 (40.0) ≥75 53 (10.4)

Median 60 - 64

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1 January 1990 to 31 December 1994 Outcome Measures: Mortality Rate Length of stay Data Source: Patients: California Office of Statewide Health Planning and Development (OSHPD) Hospitals: Licensed Services and Utilization Profiles: Annual Report of Hospitals (January 11, 1991 – December 21, 1991)

Condition: Hepatocellular carcinoma Procedure: Hepatic resection for Hepatocellular carcinoma ICD- 9 Classification: ICD–9-CM Hepatic resection for Hepatocellular carcinoma : 155.0 Training Hospital: See Table 22: Hospital characteristics Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:

Age range No. (%) of patients

<45 126 (24.8) 45-59 125 (24.6) 60-74 203 (40.0) ≥75 53 (10.4)

Median 60 - 64 Race: n(%)

White 263 (51.9) Asian 135 (26.6) Hispanic 68 (13.4) African American 20 (3.9)

Inclusion criteria: Patients were chosen from an original cohort of patients identified byICD-9-CM codes: ▪ Partial Lobectomy 50.22 ▪ Hepatic Lobectomy 50.3 Exclusion criteria: Patients without Hepatocellular carcinoma


Glasgow (1999) (Cont.) The United States of America


Year No. of Hospitals 1990 59 1991 57 1992 50 1993 45 1994 56


Low Medium High Very High 1 - 2 3 - 6 7 - 16 ≥17 90 (65.2) 32 (23.2) 12 (8.7) 4 (2.9)


Sex: n(%) Male: 293 (57.8) Female: 214 (42.2) Comorbidities (ICD-9): n(%)

Diabetes mellitus (250)

46 (9.1)

Coronary artery disease (412-414)

37 (7.3)

Chronic obstructive pulmonary disease (490-496)

36 (7.1)

Chronic nutritional deficiencies (260-263)

17 (3.4)

Congestive Heart Failure 428

9 (1.8)

Chronic renal insufficiency

6 (1.2)

Comorbidity: Mean 0.70±0.04 Cancer type: Hepatocellular carcinoma Treatment Type: NR Other: Payer source n(%)

Medicare 160 (31.6) Medi-cal 76 (15.0) Blue cross/ blue shield

28 (5.5)

Private insurance 94 (18.5)



Mortality:

Volume group Overall crude mortality* Adjusted mortality rate†‡ Low 1 - 2 24.4 22.7 Med 3 - 6 16.2 13.3 High 7 - 16 14.7 15.4 Very high ≥17 6.2§ 9.4 All 14.8 NA

* P<0.001 using logistic regression † Indicates risk adjustment for sex, age, year of operation, source of admission, type of resection, presence of chronic liver disease and presence of significant comorbid illnesses. ‡P<0.05 hospitals with 17 or more operations vs. those with 1 to 2 , 3 to 6 and 7 to 16 ; hospitals with 1 to 2 operations vs. those with 3 to 6, 7 to 16 and ≥17 ; and hospitals with ≥17 operations vs. those with 1 to 2 using multiple regression analyses.§ P<0.05, hospitals with ≥17 operations vs. those with 1 to 2 Chronic liver disease: 192/507 (37.9)

Chronic liver disease

Without chronic liver disease

P value

Mortality 27.1% 7.3 P <0.001

Comorbidities Mortality rate 0 5.0% 4 50.0%

Increasing with increasing Comorbidity P<0.001 More operations vs those with 1 to 2 , 2 to 6 nd 7 to 16, and hospitals with 17 or more operations vs those with 1 to 2, with multiple regression analysis

Other: Payer source n(%)

Health maintenance or preferred health provider organization

128 (25.5)

Other 21 (4.1)



Length of stay:

Volume group Length of hospital stay, mean ± SEM, d*

Risk adjusted length of hospital stay,d†

Length of hospital stay >75th percentile mean % ‡ §

Low 1 - 2 14.7±1.0 14.3 30.4 Med 3 - 6 13.7±1.0 13.4 28.5 High 7 - 16 12.9±1.0 13.1 24.1 Very high ≥17 10.8±0.9 11.3|| 15.8 All 12.9±0.5 … 24.3

* P<0.05 using linear regression analyses, hospitals with ≥17 operations vs. those with 1 to 2, using Tukey-Kramer honestly significant difference † Indicates risk adjustment for sex, age, year of operation, source of admission, type of resection, presence of chronic liver disease and presence of significant comorbid illnesses ‡ Indicates more than 14 days §P<0.05 using linear regression analysis, hospitals with 17 or more operations vs those with 1 to 2 and 3 to 6 , using X² analysis || P<0.05 hospitals with 17 or

Length of stay Mean ±SEM

Deceased 18.4 ± 2.24 Alive 12.0 ± 0.42

Other: Payer source n(%)

Health maintenance or preferred health provider organization

128 (25.5)

Other 21 (4.1)


Table 59: Hospital characteristics

Characteristic All 1-2 3-6 7-16 ≥17 University hospital %* 6.5 0.0 12.5 25.0 50.0 Liver Transplantation program %*

8.0 0.0 12.5 33.3 75.0

Residency training centre%* 18.7 7.0 37.5 33.3 75.0 No. of acute care beds mean, ± SEM*

302±18 243±20 337±32 493±53 734±92

No. of patient days/y mean, ± SEM*

63 877 ±4 130 47 548±4 224 74 753±6 884 114 606±11 242 171 701±19 472

No. of discharges/y mean, ± SEM*

11 906±738 9 498±789 12 643±0.2 21 273±2 099 29 056±3 637

No. of intensive care unit beds, mean, ± SEM*

21.3±1.7 14.4±1.7 28.2±2.9 39.8±4.7 56.7±8.1

No. of operations/y mean, ± SEM*

7 356±482 5 808±532 8 022±862 13 456±1 408 16 245±2 439

No. of hepatectomies for neoplasia in 1990-1994, mean, ± SEM*

55.1±1.3 6.3±1.0 19.8±0.9 52.4±1.0 139.8±0.92

Cardiac surgery centre *% 54 45.6 62.5 83.3 100 * P<0.001 by analysis of variance, linear regression analysis

Appendix C.1 Study design tables – Liver Resection (continued)

Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Hollenbeck (2007) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =3360 Age: Mean (95% CI) 58.1 (57.5-58.7) Hospital Number: Hn =NR Surgeon Number: Sn = NA Volume Definitions: Hospital: Average number of procedures performed per volume category over study period.

Low High Mean 1.0 33.8 SD 0 19.9

Surgeon: NA End Points: Morbidity: NA Mortality: %

Low High Liver Resection 13.5 5.7

Level of Evidence: III-2 Follow-up: NR Lost to Follow-up: NR Study Period: 1993-2003 Outcome Measures: Intraoperative death (Intraoperative surgical death, death during course of hospitalization) Prolonged length of stay (Patients whose length of stay was greater than the 90th percentile) Data Source: Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample (NIS)

Condition: Liver Cancer Procedure: Partial excision Lobectomy Total Hepatic Resection ICD- 9 Classification: Diagnosis 155,155.0-155.2 Procedure Partial excision 50.2, 50.22, 50.29 Lobectomy 50.3 Total Hepatic Resection 50.4 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Mean (95% CI) 58.1 (57.5-58.7) Race: %

White 53.6 African American 7.1 Hispanic 7.1 Other 12.1 Missing 20.1

Inclusion criteria: Patients undergoing their procedure for cancer diagnosis. Exclusion criteria: NR

Appendix C.1 Study design tables – Liver Resection (continued)

Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Hollenbeck (2007) (Cont.) The United States of America

Mortality: Odds Ratio for Operative Mortality (Bottom vs. Top Decile)

Unadjusted OR

95% CI Adjusted OR 95% CI

Liver Resection

2.6 1.6-4.2 2.0 1.4-2.9

C Statistic Adjusted models without

volume Adjusted models with volume

Liver Resection 0.77 0.77 Length of stay: Prolonged Length of Stay

Low High Liver Resection 11.7 8.4

Odds Ratio for Prolonged Length of Stay (Bottom vs. Top Decile)

Unadjusted OR


Liver Resection

1.4 0.7-2.9 0.9 0.5-1.6

C Statistic

Adjusted models without volume

Adjusted models with volume

Liver Resection 0.75 0.75

Sex: Women % 39.8 Comorbidities: NR Other: Admission type: % Urgent/ Emergent admission = 28.2 Insurance: % Medicare = 43.0 Private = 42.1 Other = 14.9

Appendix C 3.1 Study design tables – Liver Resection (Continued)

Table 60: Operative Mortality – Impact of regionalisation of care

Average No. of surgeries performed at a Low Volume Hospital

Adjusted attributable risk Lives Saved Lives saved per 100 000 US population

% 95% CI No. 95% CI

Liver Resection

274 46.4 25.7-60.8 190 105-248

0.07

Table 61: Prolonged Length of Stay


Adjusted attributable risk Earlier Discharges Earlier discharges per 100,000 US population

% 95% CI No. 95% CI

Liver Resection

274 -14.5 -97.5-31.5 -51 -342-110

-


Lin (2006) Taiwan

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 1872 n(%)

Very Low Low Medium High Very High 362 (19.36)

386 (20.6)

379 (20.3)

430 (23.0)

315 (16.8)

Age: Mean (SD)

Very Low Low Medium High Very High 59 (14) 58 (14) 56 (15) 52 (12) 57 (14)

Hospital Number: Hn =82 n(%)

Very Low Low Medium High Very High 63 11 4 2 2


Very Low Low Medium High Very High <25 25 - 51 52 - 186 197 - 231 >231

Volume categories were assigned by cut-offs which closely sorted patients into equal groups. Surgeon: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: January 2000 – December 2003 Outcome Measures: In-hospital mortality Data Source: Taiwan National Health Insurance Research Database

Condition: NR Procedure: Liver Lobectomy ICD- 9 Classification: ICD-9-CM NR Training Hospital: Not examined as all medical centers are and regional hospitals are teaching hospitals. Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Patient age was controlled through the use of the following categories: <45,45–64, 65-74, 75-84, >84 Race: NR Sex: Female (%)

Very Low

Low Medium High Very High

31 25 23 26 28



Lin (2006) (Cont.) Taiwan


Liver Lobectomy

Very Low Low Medium High Very High

Observed mortality (%)

4.42 2.33 1.58 0.0 0.32

Unadjusted Odds Ratio

1.00 0.52 0.23–1.18*

0.35 0.14–0.90*

† 0.07 0.01-0.52*

Adjusted Odds Ratio

1.00 0.64 0.19-2.14*

0.30 0.07-0.56*

† 0.05 0.04-0.59*

*95% CI †Statistically indeterminate Length of stay: NR

Comorbidities: ≥3 %

Very Low


36 29 30 20 22 Cancer type: NR Treatment Type: Liver Lobectomy

Appendix C 3.2: Volume outcome tables – Liver Resection Authors Volume outcome data


High volume was linked with lower mortality (P=0.04) Statistical trend analysis of decreasing mortality with increasing volume leads to P=0.04 for hepatic resection Reduction in 30-day mortality; from low volume 5.4% (95% CI, 3.6% - 7.8%) to high volume 1.7% (95% CI, 0.4%-5.0%)

Authors Volume outcome

Birkmeyer (2006)b United States of America

There was a decrease from 13.6 % mortality in very low hospital volume (quartile 1) to 8.0% in very high hospital volume (quartile 5), odds ratio= 1.82 (CI 95% 0.83 to 3.98), when adjusting for patient and hospital characteristics and all measurable processes of care.

Appendix C 3.2: Volume outcome tables – Liver Resection (Continued) Authors Volume outcome data

Choti (1998) Canada

The mortality rate for all procedures in the low volume group was 7.9% compared to 1.5% for the high volume group (P<0.01, RR=5.2) Unadjusted in-hospital mortality was higher at ther low-volume providers compared to the high volume provider for both minor and major resections (minor: 1.1% vs. 6.1%, P<0.05; major: 2.3% vs. 10.4%, P<0.05) Adjusted relative risk of mortality was higher at low volume hospitals for both minor and major resection, (minor: RR=5.3, P<0.05; major : RR=4.4, P=0.05) The mortality rate for primary liver cancer was 18.8% in the low volume provider group compared to 4.9% in the high volume groups (P≤0.05) No deaths were recorded in high volume, eight were recorded at low volume hospitals (0% vs. 5%, P=NS), in patients with metastatic disease. Comparisons of relative risk of mortality from metastatic disease did not reach statistical significance between hospital groups (RR>5.0, p=NS) Adjusted analysis shows a shorter length of stay at low volume providers (11.1 vs. 9.8 days, P<0.05) Relative risk of mortality was 5.2 times higher at low volume hospitals compared to high volume hospitals (p<0.01). No differences between low volume hospitals and high volume hospitals for all measured outcomes for non-malignant diagnosis. 7-15 resections per year equal relative risk of in-hospital mortality 3.4 times that of high volume hospitals. <7 resections per year equal relative risk of in-hospital mortality 6.4 times that of high volume hospitals.



Low volume hospitals had a 21% (95% CI; 2%-44%: P=0.03) increased length of stay and an increased total hospital cost 22%(95% CI; 1%-48%; P=0.04) High volume hospitals had a lower crude in-hospital mortality rate than low volume hospitals (11.4% vs. 2.9%; P<0.001) Surgeons with high case volumes had lower mortality rates than surgeons with low case volumes (2.7% vs. 9.7; P=0.002) No differences were found in a Univariate analysis for length of stay for patients with or without daily rounds by an ICU physician 7 days (IQR= 6-10) vs. 8 days (IQR= 6-11 P=0.9),; however in a multivariate analysis adjusting for patient and hospital characteristics, low volume hospitals are associated with a 21%(95% CI 2%-44%, P= 0.03) increase length of stay.


Dimick (2003) The United States of America It is likely that this review contains sections of the same patient cohort as reported in Dimick (2002)

Overall mortality rate was 4.8% and was significantly lower in high volume hospitals (2.8%) than in low volume hospitals (10.2%) P<0.001. After adjusting for case mix analysis low hospital volume was associated with a 3-fold increase in mortality (OR 3.1; 95% CI 1.2-7.6; P=0.02)


Dimick (2003b) The United States of America

Higher-volume centres had significantly lower mortality rates for both resection of hepatic metastases (P=0.05) and primary hepatic malignancy (P=0.008) High volume hospitals had a significantly lower patient mortality rate of (3.9%) in comparison to low volume hospitals (7.6%), (p<0.001) Lobectomy patients had a higher mortality rate than patients receiving wedge resection (p=0.002) High volume hospital 0.6 95% CI, (0.4-0.9); P=0.02



The decline in mortality was greater in HVH (10.1 – 3.9, P<0.001) than LVH (10.6 – 7.4, P=0.01) Mortality rate: HVH: 5.8 % vs. LVH: 8.9 % P<0.001


Fong (2005) The United States of America

Log rank for superior survival at high volume centres (P=0.02) The relative risk of death at a Low volume hospital is 1.8 Patients treated at high volume hospitals had a significantly reduced likelihood of mortality (p=0.02)



Unadjusted Relative Risk - Mortality Overall Very low Low Medium High NA 4.7

(1.6-13.4) P<0.01

4.3 (1.4-13.5) P<0.05

1.6ns (0.5-5.1)

1.0

Adjusted Relative Risk - Mortality Overall Very low Low Medium High NA 4.7

(1.6-13.7) P<0.01

3.8 (1.2-12.4) P<0.05

1.5ns (0.5-4.9)

1.0

Length of stay was reportedly longer at lower volume hospitals however this was not tested for statistical significance.


Glasgow (1999) The United States of America

The relationship between decreasing mortality and increasing volume is significant to (P<0.001) Overall operative mortality rate 6.9%, ranging from 9.3% in the lowest-volume hospitals to 4.1% in the highest-volume hospitals


Hollenbeck (2007) The United States of America

Adjusted mortality 2.0 (95% CI, 1.4-2.9) between lowest and highest volume decile. Unadjusted mortality2.6 (95% CI, 1.6-4.2) between lowest and highest volume decile. Adjusted prolonged length of stay 0.9 (95% CI, 0.5-1.6) between lowest and highest volume decile. Unadjusted prolonged length of stay 1.4 (95% CI, 0.7-2.9) between lowest and highest volume decile.


Lin (2006) Taiwan

Liver Lobectomy Very Low Low Medium High Very High Observed mortality (%) 4.42 2.33 1.58 0.0 0.32 Unadjusted Odds Ratio 1.00 0.52

0.23–1.18* 0.35 0.14–0.90*

† 0.07 0.01-0.52*

Adjusted Odds Ratio 1.00 0.64 0.19-2.14*

0.30 0.07-0.56*

† 0.05 0.04-0.59*

*95% CI †Statistically indeterminate

Appendix C 3.3: Financial Data – Liver Resection Authors Financial data

Choti (1998) The United States of America

Unadjusted average cost

Classification Average total charge By procedure High Volume Low Volume P value All procedures 17,923.49 22,485.24 0.49 Minor (Partial Hepatectomy) 16,340.23 17,747.56 0.08 Major (≥Hepatic Lobectomy) 21,090.02 28,999.56 0.02 By diagnosis Primary liver cancer 20,312.83 26,848.67 0.70 Metastatic cancer 17,273.92 17,603.39 0.68 All other diagnoses 17,095.89 26,751.30 0.42

Adjusted average cost

Classification Average total charge By procedure High Volume Low Volume P value All procedures 15,434.80 15,326.42 0.90 Minor (Partial Hepatectomy) 14,730.56 12,425.31 <0.01 Major (≥Hepatic Lobectomy) 17,127.41 20,318.97 0.08 By diagnosis Primary liver cancer 18,184.93 18,505.02 0.90 Metastatic cancer 14,445.41 14,137.53 0.76 All other diagnoses 14,854.96 15,925.39 0.53

Average total charge $20,498 Hospital costs were adjusted for age, sex, race and number of comorbidities. Multiple regression models for average total charge. Total charges were $17,085 and $25,999 for minor and major resections (P<0.001) respectively The average total charges were higher at low volume providers for major resections ($21,090 vs. $30,000 p<0.05) The average total charges for a primary liver malignancy were $23,191 compared to $17,459 for metastatic disease

Appendix C 3.3: Financial Data – Liver Resection (Continued) Authors Financial data


In the study by Dimick (2002) operative cost was assessed in relation to the presence or absence of an Intensive Care Unit physician. However the presence or absence of this physician is not contingent on a high or low volume classification. Univariate analysis of cost and presence/absence of ICU Physician daily rounds.

Outcome variable All patients No daily rounds by ICU physician Daily rounds by ICU physician P Total health care cost median, (IQR) $12,630

($9,425-$17,643) $13,777 ($9,534-$19,751)

$11,935 ($9,359-$16,337)

0.0006

The above charges do not include professional fees, and are adjusted to 1998 dollars (USD) using a consumer price index for health care After multivariate analysis hospital volume was significantly associated with an increase in hospital costs (22%; 95% CI, 1-48%; p=0.04). Other factors were also identified as being significantly associated with increased cost.

Factors % Increase in hospital charges 95% CI P Urgent admission 23 % 2-47 % 0.03 Hepatic Lobectomy 24 % 9-37 % 0.005 Male gender 14 % 2-25 % 0.02

Multivariate analysis of total hospital cost related to patient and hospital characteristics

Characteristic Rate % 95% CI P Patient Age 0 (0-0%) Male sex 14 (2-25) p<0.05 Non-white 11 (-2-22) Hepatic Lobectomy 24 (9-37) p<0.05 Urgent admission 23 (2-47) p<0.05 Emergent admission 32 (-4-81) Hospital Absence of daily rounds by ICU physician 14 (-1-27) Low volume hospital 22 (1-48) p<0.05 Low volume surgeon 7 (-7-23)

Appendix C 3.3: Financial Data – Liver Resection (Continued) Authors Financial data


There was a significantly decreased hospital cost at high volume centres (Median $10,840; IQR $7,1181-$16,803) compared with low-volume (median, $11,776; IQR, $9,160-$16,577).

Outcome variable All patients High Volume Low Volume P value Health care cost $12,630

($9,425-$17,643) $10,840 ($7,181-$16,803)

$11,776 ($9,160-$16577)

P=0.05


STUDY DESIGN TABLES

Appendix C 4.1: Study design tables – Oesophagectomy Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria

Bachmann (2002) United Kingdom

Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume Population Number: Pn = 781 Age: NR Hospital Number: Hn = 23 hospital trusts Surgeon Number: Sn = NR Volume Definitions: Hospital: median (range; interquartile range) 42 (13-83; 24-66) Surgeon; median (range; interquartile range): 12 (1-48; 6-25)

Surgeon Volume according to quartiles Very Low Low Medium High Surgical volumes

1 10 20 40

End Points: Morbidity: NR Mortality: Unadjusted Odds Ratio (95% CI) according to surgeon volume

Very low Low Medium High 0.95 (0.92- 0.99)

0.61 (0.42-0.89)

0.38 (0.18-0.79)

0.14 (0.03-0.63)

Note: terminology of categories applied by reviewer

Level of Evidence: III-2 Follow-up: NR Lost to Follow-up: NR Study Period: July 1996 to June 1997 Outcome Measures: Mortality Data Source: NHS Central Register

Condition: NR Procedure: Oesophagectomy ICD- 9 Classification: ICD-9-CM NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: NR Race: NR Sex: NR Comorbidities: NR

Inclusion criteria: This study examined six procedures. Patients included for excision of the oesophagus had an ICD-9-CM code of 42.40 Exclusion criteria: Numerous non-complex surgical procedures were excluded, including: ▪ 41.5 Total splenectomy ▪ 43.7 distal gastrectomy

with Jejunum anastomosis ▪ 44.31 to 44.39

gastroenterostomy ▪ 45.71 to 45.79 Distal large

bowel excision ▪ 45.90 to 45.95 intestinal

anastomosis ▪ 46.01 to46.04

exteriorization of the bowel ▪ 46.10 to 46.14 colostomy ▪ 52.51 to 52.59 distal

pancreatectomy

Appendix C 4.1: Study design tables – Oesophagectomy (Continued) Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria

Bachmann (2002) (Cont.) United Kingdom

Adjusted Odds Ratio (95% CI)

Very low Low Medium High 0.95 (0.90-1.00)

0.60 (0.36-0.99)

0.35 (0.18-0.79)

0.14 (0.03-0.63)

Note: terminology of categories applied by reviewer Length of stay: NR

Cancer type: NR Treatment Type:

Treatment Prevalence, % Resection 31

Stent 38 Dilatation 37

Chemotherapy 24 Radiotherapy 11

None of the above

10

Type of admission: NR

Appendix C 4.1: Study design tables – Oesophagectomy (Continued) Authors Procedure Study Design Procedure Inclusion/Exclusion

Criteria Begg (1998) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: No. of oesophageal cancers: 6782 No. of procedures: 503 (7.4% of cases) Age: 65 years +

Age at Diagnosis, % Volume 65-69y 70-74y ≥75y 1-5 34 38 28 6-10 43 31 26 ≥11 40 33 27

Hospital Number: Hn = 503 Surgeon Number: Sn = NA Volume Definitions: Hospital:

Low Medium High 1-5 6-10 ≥11

Level of Evidence: III-3 Follow-up: 30 days Lost to Follow-up: NR Study Period: 1984-1993 Outcome Measures: 30 Day Operative Mortality Data Source: Surveillance, Epidemiology and End Results (SEER)-Medicare Linked Database Medicare Provider Analysis and Review

Condition: Cancer of the oesophagus (ICD-9-CM 150) Procedure: Oesophagectomy not otherwise specified Partial oesophagectomy Total oesophagectomy ICD- 9 Classification: 42.40 (CM) 42.41 (CM) 42.42 (CM) Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: 65 years +

Age at Diagnosis, % Volume 65-69y 70-74y ≥75y 1-5 34 38 28 6-10 43 31 26 ≥11 40 33 27

Race: NR

Inclusion criteria: Patient for whom procedure was performed within 2 months of diagnosis Exclusion criteria: NR


Criteria Begg (1998) (Cont.) The United States of America

Volume Definitions: Hospital: (Cont.)

Volume No. of Esophagectomy Procedures

1 95 2 60 3 66 4 76 5 15 6 48 7 14 8 32 9 9 10 NA 11 22 12 12 13 13 14 NA 15 NA 16 NA 17 NA 18 18 19 NA 20 NA 21 NA 22 NA 23 23


Comorbidities:

Comorbidity Index, % Volume 0 1 ≥2 1-5 74 21 4 6-10 81 17 3 ≥11 89 9 2

Location: NR Stage:

Treatment: NR

Stage, % Volume Local Regional Distant Unstaged 1-5 33 50 6 11 6-10 38 43 16 4 ≥11 34 59 3 3


Criteria Begg (1998) (Cont.) The United States of America

Mortality:

Volume % Mortality 1 20 2 18 3 26 4 8 5 7 6 2 7 14 8 3 9 0 10 NA 11 5 12 8 13 0 14 NA 15 NA 16 NA 17 NA 18 0 19 NA 20 NA 21 NA 22 NA 23 4

Mortality rates by hospital volume:

Volume 30-Day Mortality Rate % 1-5 17.3 6-10 3.9 ≥11 3.4

P values for the effects of mortality using logistic regression for oesophagectomy P<0.01 30 Day Average mortality rate P<0.001 Length of stay: NR


Criteria Birkmeyer (2002) United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 6337 Medicare patients Patients eligible for travel time analysis= 5971

Very Low Low Medium High Very High Medicare Patients

861 (14) 1817 (29) 1091 (17) 1393 (22) 1175 (19)

Very Low Low Medium High Very High Patients eligible for time travel analysis

825 (14) 1734 (29) 1053 (18) 1330 (22) 1029 (17)

Age:


Age>75yr 31.9 31.7 31.3 28.6 28.1 Hospital Number: n (%) Hn = 1575

Very Low Low Medium High Very High Hospitals, No

618 (39) 620 (39) 187 (12) 119 (8) 31 (2)

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1994-1999 Outcome Measures: Operative mortality (rate of death before hospital discharge/ within 30 days of index procedure) Additional travel time required Data Source: Medicare Provider Analysis and Review

Condition: Esophageal Cancer Procedure: Esophagectomy ICD- 9 Classification: ICD 42.40-42, 43.99 Training Hospital: NR Institutional/Environmental Support: Dartmouth Medical School Selective Referral: NR Covariates: Age:

Very Low


Age>75yr 31.9 31.7 31.3 28.6 28.1 Race:

Very Low


Black 12.0 7.6 6.7 6.5 5.5

Inclusion criteria: Surgical procedure including esophagectomy Patients receiving one of six different types of cardiovascular procedures and eight types of major cancer resections were reported in this study. However, only the esophagectomy data is included in this analysis. Exclusion criteria: 10% of medicare patients (those not covered by fee-for-service arrangements) Patients under 65 years of age or over 99 years Information on coexisting conditions identified at previous admissions that occurred within two weeks before index hospitalisation


Criteria Birkmeyer (2002) (Cont.) United States of America


Very Low Low Medium High Very High Avg. No. of procedures/yr

<2 2-4 5-7 8-19 >19

Surgeon: NR End Points: Morbidity: NR Mortality:

Very Low Low Medium High Very High Observed mortality rate (%)

23.1 18.9 16.9 11.7 8.1

Adjusted Mortality

(%)

20.3 17.8 16.2 11.4 8.4

Unadjusted odds ratio (95% CI)

1.0 0.78 (0.63-0.95)

0.68 (0.54-0.86)

0.44 (0.35-0.55)

0.29 (0.21-0.40)

Adjusted odds ratio (95% CI)

1.0 0.85 (0.69-1.05)

0.76 (0.60-0.97)

0.51 (0.40-0.64)

0.36 (0.26-0.50)

Length of stay: NR

Comorbidities:

Very Low


Charlson Score ≥3

43.3 43.3 45.4 41.6 43.0

Charlson Score (number of coexisting conditions, weighted according to their relative effects on mortality) Location: NR Stage: NR Treatment: Esophagectomy


Birkmeyer (2003) United States of America It is likely that patients from this study are also reported in Birkmeyer (2006)

Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume Population Number: Pn = NR Age:

Low Medium High

Age >75yr 31.2 31.6 31.0 Hospital Number: Hn = NR Surgeon Number: Sn = NR Volume Definitions: Hospital:

Low Medium High Avg. No. of procedures/yr

<5.0 5.0-13.0 >13.0

Surgeon:

Low Medium High Avg. No. of procedures/yr

<2.0 2.0-6.0 >6.0

Surgeon Volume Adjusted odds ratio (95%)

Surgeon Volume, Adjusted for hospital volume Adjusted odds ratio (95%)

Proportion of Effect of Surgeon Volume Attributable to Hospital Volume %

2.30 (1.54-3.42) 1.80 (1.13-2.87) 38

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1998-1999 Outcome Measures: Operative mortality (rate of death before hospital discharge/ within 30 days of index procedure) Data Source: Centre of Medicare and Medicaid Services and The Medicare Provider Analysis and Review (MEDPAR) Characteristics of hospitals were from the American Hospital Association

Condition: Esophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: ICD 42.40-42, 43.99 Training Hospital: NR Institutional/Environmental Support: Dartmouth Medical School Selective Referral: NR Covariates: Age:

Low Medium High

Age>75yr 31.2 31.6 31.0 Gender:

Low Medium High

Female Sex

24.4 25.1 21.5

Race:

Low Medium High

Black 8.7 6.8 4.3

Inclusion criteria: Patients who underwent one of eight cardiovascular procedures or cancer resections were also reported in this study. However, only the esophagectomy data is included in this analysis.


Criteria Birkmeyer (2003) (Cont.) United States of America It is likely that patients from this study are also reported in Birkmeyer (2006)


ANNUAL SURGEON VOLUME Low Medium High

Adjusted Mortality

(%)

18.8 13.1 9.2

Cutoff

No./year Hospital Volume<Cutoff Hospital Volume≥Cutoff

13 Low-Volume Surgeons

High Volume Surgeons

Overall Hospital Mean

Low-Volume Surgeons

High Volume Surgeons

Overall Hospital Mean

Proportion of Patients

36.0 14.4 9.2 70.0

Mortality 19.2 11.1 15.3 17.5 8.1 9.5

Mortality according to hospital and surgeon volume Annual Surgeon Volume

Low <2.0 Medium 2.0-6.0 High >6.0 Low <5.0 21.7 14.7 - Medium 5.0-13.0

14.6 13.3 9.8

Annual Hospital

Volume

High >13.0

17.2 9.8 8.0

Adjusted Odds Ratio for Surgeon related Mortality

Hospital Volume Adjusted odds ratio (95% CI)

Hospital Volume, Adjusted for surgeon volume Adjusted odds ratio (95% CI)


2.23 (1.47-3.39) 1.67 (1.02-2.73) 46

Comorbidities:

Low Medium High Charlson Score ≥3

42.4 41.8 42.4

Charlson Score (number of coexisting conditions, weighted according to their relative effects on mortality) Location: NR Stage: NR Treatment: Oesophagectomy

Exclusion criteria: Patients who did not have an accompanying diagnosis code for cancer Records containing invalid provider ID numbers (6%) Patients under 65 years of age or over 99 years


Birkmeyer (2003) (Cont.) United States of America It is likely that patients from this study are also reported in Birkmeyer (2006)

Adjusted Odds Ratio for Hospital related Mortality

Hospital Volume Adjusted odds ratio (95% CI)

Hospital Volume, Adjusted for surgeon volume Adjusted odds ratio (95% CI)


2.23 (1.47-3.39) 1.67 (1.02-2.73) 46 Length of stay: NR


Birkmeyer (2004) United States of America


Patients in US

Patients in nonrural hospitals (%)

Patients at hospitals not meeting EHR criteria (%)

Volume Criteria Volume and process criteria

Volumes and outcome criteria

Annual Number of US Patients (%)

4350 4132 3058 (74%) NA NA

Age: NR Hospital Number: Hn = NR Surgeon Number: Sn = NA Volume Definitions: Hospital:

Low volume hospital High volume hospital <13 ≥13

Surgeon: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 2000-2003 Outcome Measures: Operative mortality (rate of death before hospital discharge/ within 30 days of index procedure) Total lives saved by new EHR standards Data Source: 2000 Nationwide Inpatient Sample

Condition: Esophageal Cancer Procedure: Esophagectomy ICD- 9 Classification: ICD 42.40-42, 43.99 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: NR Gender: NR Race: NR Comorbidities: NR Location: NR

Inclusion criteria: Patients who underwent one of five procedures targeted by the Leapfrog Group. However, only esophagectomy data was included in this analysis. Exclusion criteria: NR


Birkmeyer (2004) (Cont.) United States of America


Low <13 High ≥13 In-patient Mortality

(%)

11.1 5.2

Lives Saved:

Lives Saved with implementation of Leapfrog Volume

Criteria Volume and Process Criteria

Volume and outcomes criteria

Total lives saved by new EHR standards

Oesophagectomy 180 NA NA 180 Length of stay: NR

Stage: NR Treatment: Esophagectomy


Birkmeyer (2006) United States of America It is likely that a smaller subgroup of patients included in this study Is reported in Birkmeyer (2003)b

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 4349 Age: NR Hospital Number: Hn = NR Surgeon Number: Sn = NA Volume Definitions: Hospital:

Hospitals ranked by procedure volume: 1 (Worst) 2 3 4 5 (Best) Average annual volumes

<1.3 1.3-2.0 2.1-3.0 3.1-7.3 >7.3


Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1994-2001 Outcome Measures: Operative mortality (rate of death before hospital discharge/ within 30 days of index procedure) Data Source: Centre for Medicare and Medicaid Services The Medical Provider Analysis and Review (MEDPAR)

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: NR Training Hospital: NR Institutional/Environmental Support: Dartmouth Medical School Selective Referral: NR Covariates: Age: NR Gender: NR Race: NR Comorbidities: NR Location: NR Stage: NR

Inclusion criteria: Patients who underwent one of four procedures targeted by the Leapfrog Group. However, only esophagectomy data was included in this analysis. Patients aged between 65-99 years. Exclusion criteria: Patients with noncancer diagnoses (15%)


Birkmeyer (2006) (Cont.) United States of America It is likely that a smaller subgroup of patients included in this study Is reported in Birkmeyer (2003)b

Mortality:

Hospitals ranked by risk-adjusted historical mortality 1 (Worst) 2 3 4 5 (Best)

Actual Mortality

(%)

53.1 18.6 2.9 1.9 2.1

Expected Mortality

(%)

16.6 16.2 14.5 16.1 15.7

Hospitals ranked by historical Volume

Average annual

volumes

<1.3 1.3-2.0 2.1-3.0 3.1-7.3 >7.3

Actual Mortality

(%)

21.8 17.1 16.9 13.3 8.1

Expected Mortality

(%)

16.8 16.3 15.9 15.3 14.2

Treatment: Oesophagectomy



Subsequent Mortality (%), by Quintile of Historical Volume

1 (Worst) 2 3 4 5 (Best) 1994-1997

ranking vs 1998-

1999

20.0 16.6 13.1 12.3 7.5

1996-1999

ranking vs. 2000-

2001

18.9 14.1 12.7 12.1 7.5

Historical Volume

1994-1997

ranking vs. 2000-

2001

18.9 14.6 12.4 11.5 8.1

Subsequent Mortality (%), by Quintile of Historical Mortality

1 (Worst) 2 3 4 5 (Best) 1994-1997

ranking vs 1998-

1999

12.9 14.3 18.5 12.3 11.4

1996-1999

ranking vs. 2000-

2001

16.7 12.9 15.1 13.0 9.4

Historical Mortality

1994-1997

ranking vs. 2000-

2001

15.9 11.4 20.6 12.0 8.0



Length of stay: NR


Birkmeyer (2006)b United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Data was pooled according to all procedures, therefore oesphagectomy-specific data was not available. Age: Data was pooled according to all procedures, therefore oesphagectomy-specific data was not available. Hospital Number: Data was pooled according to all procedures, therefore oesphagectomy-specific data was not available. Surgeon Number: NA Volume Definitions: Hospital: Data was pooled according to all procedures, therefore oesphagectomy-specific data was not available. Surgeon: NA End Points: Morbidity: NR

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 2000-2002 Outcome Measures: Operative Death (Death before discharge or within 30 days of the procedure) Data Source: National Medicare Claims Databases

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Data was pooled according to all procedures, therefore oesphagectomy-specific data was not available. Gender: Data was pooled according to all procedures, therefore oesphagectomy-specific data was not available. Race: Data was pooled according to all procedures, therefore oesphagectomy-specific data was not available.

Inclusion criteria: Procedures potentially related to operative mortality were considered for this study however, for the present analysis only oesophagectomy data was analysed. Patients aged 65-99

Exclusion criteria: NR


Birkmeyer (2006)b (Cont.) United States of America

End Points: Mortality:

Hospital Volume Quintile Odds ratio (low vs high) (95% CI)

1 2 3 4 5 Adjusted for patient and hospital characteristics

15.5 15.2 11.6 9.9 6.8 2.52 (1.70-3.74)

Adjusted for patient and hospital characteristics and all measurable processes of care

15.2 14.4 11.3 9.7 7.1 2.34 (1.58-3.46)

Length of Stay: NR There was a decrease from 15.2 in very low hospital volume (quartile 1) to 7.1% in very high hospital volume (quartile 5), odds ratio= 2.34 (CI 95% 1.58 to 3.46), when adjusting for patient and hospital characteristics and all measurable processes of care.

Comorbidities: n(%) Data was pooled according to all procedures, therefore oesphagectomy-specific data was not available. Type of Admission: NR Location: NR Stage: NR Treatment: Oesophagectomy


Criteria Dimick (2001) United States of America


Low Volume Hospitals

Medium Volume Hospitals

High Volume Hospitals

Number of patients (%)

445 (39%) 291 (26%) 400 (35%)

Age:

Total Low Medium High P value Age, mean (SD)

61 (13) 62 (12) 61 (13) 59 (14) <0.001


Low Volume Medium Volume High Volume Hospitals, n 39 20 3


Low Volume Medium Volume High Volume Procedures per

year ≤3 4-15 >15


Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1984-1999 Jan-Sept Outcome Measures: In-patient mortality Length of Stay Charges Data Source: Uniform Health Discharge Data Set maintained by the Maryland Health Services Cost Review Commission

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: ICD-9-CM 4240-42 Training Hospital: NR Institutional/Environmental Support: John Hopkins Hospital Selective Referral: NR Covariates: Age:

Total Low Medium High P value

Age, mean (SD)

61 (13)

62 (12)

61 (13) 59 (14)

<0.001

Gender:


Sex, male %

74 74 72 76 0.4

Inclusion criteria: Patients diagnosed with one of three ICD-9-CM codes within the defined durcations Exclusion criteria: Patients < 65 or >99 years of age


Criteria Dimick (2001) (Cont.) United States of America

Mortality:

Total Low Medium High P value Time Period 1 (1984-1989) Mortality rate, %

13.3 15.9 13.7 3.7 0.02

Time Period 2 (1990-1994) Mortality rate, %

11.5 19.6 10.8 5.0 <0.001

Time Period 3 (1995-1999) Mortality rate, %

6.4 12.1 13.5 0.6 <0.001

Overall (1984-1999) Mortality rate, %

10.5 16 12.7 2.7 <0.001

Risk of Death

Volume: Adjusted OR 95% CI Medium 0.73 0.47-1.10

High 0.21 0.10-0.42 Age >65 y 1.04 1.02-1.06

Male Sex 1.0 0.64-1.54 Non-white race 1.75 1.12-2.74 Time Period:

1990-1994 1.12 0.71-1.80 1995-1999 0.65 0.37-1.14

Admission Urgent -

Emergent - Malignancy - Renal Disease 7.73 0.93-64.0

Race:

Total Low Medium High P value Race, white %

76 72 70 84 <0.001

Comorbidities:


Malignancy, %

83 87 87 77 <0.001

COPD, % 14 17 12 12 0.04 Diabetes Mellitus, %

7 7 8 7 0.9

History of MI, %

2 1 1 4 0.008

Location: NR Stage: NR Treatment: Oesophagectomy Nature of Admission:


Elective 64% 67% 64% 61% 0.3 Urgent/Emergent 36% 33% 36% 39% 0.3


Dimick (2001) (Cont.) United States of America

Mortality: Other univariate predictors of death were nonwhite race (p=0.004), extent of resection (p=0.02), age (p<0.001), urgent and emergent admission (p<0.001) and chronic renal disease (p-0.01). Length of stay:

Total Low Medium High P value Time Period 1 (1984-1989) Length of Stay

22 (14-24) 22 (15-34)

24 (15-38) 17 (12-29) 0.004

Time Period 2 (1990-1994) Length of Stay

16 (11-26) 22 (14-36)

18 (13-29) 11 (10-18) <0.001

Time Period 3 (1995-1999) Length of Stay

10 (8-17) 13 (10-22)

15 (11-26) 8 (8-11) <0.001

Overall (1984-1999) Length of Stay

16 (10-27) 19 (12-33)

20 (13-31) 11 (9-16) <0.001

Length of stay and charges presented as median number of days and the interquartile range. Significant reduction in length of stay was also seen for patients who underwent operations during time period 4 (1995-1999), p<0.001



Length of Stay

Volume: Adjusted % Increase 95% CI Medium 0.00 -10.0 to 11.0

High -32.0 -46.0 to -27.0 Age >65 y 0.00 0.00 to 1.0

Male Sex 9.0 1.0 to 17.0 Non-white race 25.0 -11.0 to 76.0 Time Period:

1990-1994 -10.0 -19.0 to 0.00 1995-1999 -34.0 -44.0 to -22.0

Admission Urgent -

Emergent - Malignancy - Renal Disease 51.0 24.0 to 83.0

Other univariate predictors of increased length of stay in a univariate analysis were older age (p=0.02), male sex (p=0.002), diabetes mellitus (p=0.002), malignant disease (p=0.003), metastatic disease (p=0.004), history of myocardial infarction (p=0.0004), renal disease (p=0.05), peripheral vascular disease (p=0.06) and having a total of three or more comorbidities (p=0.04).


Dimick (2003) United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 1,226

Low Volume High Volume Patients, N 636 590

Age:

Low Volume High Volume Age (Mean±SD) 63±13 61±14

Hospital Number: Hn = NR Surgeon Number: Sn = NA Volume Definitions: Hospital: Median annual hospital volume for oesophageal resection was greater than 6 Surgeon: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1996-1997 Outcome Measures: Complications Data Source: Nationwide Inpatient Sample (NIS)

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: ICD-9-CM 4240,4241,4242 Training Hospital: NR Institutional/Environmental Support: Dartmouth Medical School Selective Referral: NR Covariates: Age:

Low Volume

High Volume

Age (Mean±SD)

63±13 61±14

Gender: n (%)

Low Volume

High Volume

Female Gender

142 (22) 133 (23)

Race: n (%)

Low Volume

High Volume

Nonwhite race

76 (15) 55 (11)

Inclusion criteria: Patients who underwent one of three procedures with a high risk of postoperative morbidity and mortality. However, only Oesophagectomy data was included in this analysis.




Risk of Mortality after complications Complication Oesophageal Resection OR (95% CI)

Aspiration 1.9 (1.2-3.1) Cardiac complications 2.9 (1.7-4.8) Postoperative infection 2.6 (1.1-6.0)

Pneumonia 2.2 (1.1-4.3) Pulmonary failure 5.2 (3.3-8.3)

Renal failure 14.0 (7.5-26) Septicemia 16.2 (9.5-27)

Surgical Complications 2.2 (1.3-3.7) Oesophageal resection mortality was 16.9% for patients with at least one complication and 2.5% for those without complications (OR 9.7; 95% CI 5.5 to 17.3; p<.001) Patients at LVH are at higher risk of medical complications that are often indirectly related to the operation. Surgical complications associated with a 2- to 4- fold increase in risk of death after Oesophagectomy Length of stay: NR

Comorbidities: n(%)

Low Volume

High Volume

Comorbidity score

0 331 (52) 357 (61) 1 184 (29) 151 (26) 2 69 (11) 61 (10)

3 or more 52 (8) 21 (4) Location: NR Stage: NR Treatment: Oesophagectomy Type of Admission: n(%)

Low Volume

High Volume

Urgent Admission

80 (15) 61 (11)

Emergent Admission

62 (12) 38 (7)

Exclusion criteria:

Patients with noncancer diagnoses (15%)


Criteria Dimick (2003b) United States of America This paper is likely to contain data included in Dimick (2003) and Dimick (2004)


Low Medium High Very High Patients, N (%) 895 (30) 653 (22) 791 (26) 684 (23)

Age:

Low Medium High Very High Age 63±13 62±13 62±12 641±12

* Data reported as 641 but this seems unlikely; more likely 64 or 61 Hospital Number: Hn =

Year Total No. of Hospitals 1995 210 1996 204 1997 202 1998 189 1999 192


Low Medium High Very High Hospital Volume Quartiles

<3 3-5 6-16 >16

Surgeon: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1995-1999 Outcome Measures: In-Hospital Mortality Length of Stay Data Source: Nationwide Inpatient Sample (NIS)

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:


Age 63±13 62±13 62±12 64±12 Gender:


Female, n(%)

203 (23)

140 (21)

169 (21)

157 (23)

Race:


Nonwhite, n(%)

111 (15)

89 (18) 60 (11)

68 (11)

Inclusion criteria: * any patient discharged from a NIS hospital from 95-99 w/ an ICD-9-CM code for oesophageal resection Exclusion criteria: NR


Criteria Dimick (2003b) (Cont.) United States of America This paper is likely to contain data included in Dimick (2003) and Dimick (2004)

End Points: Morbidity: NR Mortality: Overall mortality rate from 1995-1999 was 8.2%

Low Medium High Very High In-hospital mortality, %

11.8 10.2 6.4 3.7

Other univariate analysis factors included female sex (p=0.004), nonwhite race (p=0.02), extent of resection (p=0.005), history of chronic obstructive pulmonary disease (p=0.08), chronic liver disease (p<0.001) and chronic renal insufficiency (p=0.002). In the multivariate analysis, other variables significant variables included age of 71 to 80 years (OR,2.5;95% CI, 1.6-2.5;p=0.001), age greater than 80 years (OR, 3.2; 95% CI, 1.6-6.1; p=0.001, urgent admission (OR, 1.9;95% CI, 1.3-3.0; p=0.003), emergent admission (OR, 2.3; 95% CI, 1.4-3.7; p=0.001) and nonwhite race (OR, 1.9 95% CI, 1.2-3.0; p=0.03). See table under volume outcome data. Admission status was also a factor with increases for elective (66%), urgent (13.8%) and emergent (17.3

Comorbidities: n(%)


Malignancy 748 (84)

535 (82)

641 (81)

563 (82)

Metastases 290 (32)

224 (34)

261 (33)

238 (35)

COPD 131 (15)

84 (13) 78 (10)

44 (6)

Diabetes Mellitus

97 (11)

60 (9.2) 66 (8.3)

47 (6.9)

History of MI

23 (2.6)

11 (1.7) 22 (2.8)

22 (3.2)

PVOD 20 (2.2)

6 (<1) 13 (1.6)

8 (1.2)

Liver Disease

14 (1.6)

9 (1.4) 7 (<1)

7 (1)

Location: NR Stage: NR Treatment: Oesophagectomy Type of Admission: n(%)


Urgent admission

128 (17)

56 (10) 93 (13)

43 (7)

Emergent Admission

76 (10)

58 (10) 50 (7)

32 (6)


Dimick (2003b) (Cont.) United States of America This paper is likely to contain data included in Dimick (2003) and Dimick (2004)

Length of stay: Overall median=13 days (interquartile range, 10-20 days) Length of stay greater than 75th percentile of 20 days considered to have prolonged stay Patients at very-high volume hospitals were less likely to have prolonged LOS compared with low-volume hospitals (20% vs 28%; p<0.001)

Univariate Analyses Length of Stay, % P value Volume

Very high volume 20.0 <0.001 Low-volume 28.0 <0.001

Nature of Admission Elective 21.0 <0.001 Urgent 33.0 <0.001

Emergent 50.0 <0.001 Other factors associated with prolonged LOS include increasing age (p<0.001), non white race (p<0.001), COPD (p<0.001), malignant indication for surgery (p=0.02) and history of chronic renal insufficiency (p<0.001)

Multivariate analyses Odds Ratio (95% CI) P value Hospital Volume

Low 1.5 (1.1-2.0) p=0.01 Medium 1.4 (1.0-1.9) p=0.03

Age 61-70 1.4 (1.1-1.8) P=0.01 71-80 1.5 (1.1-2.0) P=0.04

>80 1.7 (1.0-2.7) P=0.03 Nature of admission

Urgent 2.0 (1.5-2.7) P<0.001 Emergent 3.6 (2.6-5.0) P<0.001

Nonwhite Race 1.8 (1.4-2.5) P<0.001 COPD 1.5 (1.1-2.0) P=0.007


Dimick (2003c) United States of America


Low High Patients, N (%) 162 (44) 204 (56)

Age:

Low High Age 63±12 59±12

Hospital Number: Hn = 35 hospitals (2 HVHs and 33 LVHS) Surgeon Number: Sn = NA Volume Definitions: Hospital: Surgeon: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1994-1999 Outcome Measures: Mortality Morbidity/Complications Data Source: Uniform Health Discharge Data Set maintained by Maryland Health Services Cost Review Commission (HSCRC)

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: ICD-9-CM 42.40-42 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:

Low High Age 63±12 59±12

Gender:

Low High Male, n(%)

43 (27) 45 (22)

Race:

Low High Nonwhite,

n(%) 43 (27) 26 (13)

Inclusion criteria: Exclusion criteria: NR


Dimick (2003c) (Cont.) United States of America

End Points: Morbidity: Overall complication rate=43% 22% with one complication, 11% with two complications, 4% with three complications, 5% having four or more complications

No. of Patients needing to be referred to HVH to prevent one death

Outcome Variable Absolute Risk Reduction, %

Number needed to refer to high-volume hospital

Mortality 12.9 8

Incidence of Postoperative Complications Complication High-volume

(n=204) Low-volume (n=162)

P

Pulmonary failure 2.9 11.8 0.001 Myocardial infarction

0.5 1.2 0.4

Renal failure 0.5 8.0 <0.001 Aspiration 16 34 0.001 Cardiac complications

16 13 0.4

Pneumonia 8.8 14 0.1 Postoperative infection

3.4 6.2 0.2

Reintubation 7.8 27 <0.001 Surgical complications

6.9 14 0.03

Septicemia 1.5 6.2 0.02

Comorbidities: n(%)

Low High Malignancy 131

(81) 163 (80)

Metastases 51 (33) 51 (25) COPD 36 (22) 20 (10)

Diabetes Mellitus

1(<1) 2(1)

History of MI 6(4) 7(3) Cerebrovascular

disease 1(<1) 2(1)

Renal disease 1(<1) 1(<1) Liver Disease 1(<1) 2(1)


Low High Elective

admission 118 (73) 189 (93)

Urgent admission

18 (11) 11 (5)

Emergent Admission

25 (15) 3 (1.5)



Risk of Postoperative complications at Low-Volume Hospitals

Outcome variable Unadjusted Odds Ratio (95% CI)


Adjusted p

Renal failure 18 (2.3 to 136) 19 (1.9 to 178) 0.01 Pulmonary failure 4.4 (1.7 to 11) 4.8 (1.6 to 14) 0.002 Septicemia 4.4 (1.2 to 16) 4.0 (1.1 to 15) 0.04 Reintubation 4.2 (2.3 to 7.9) 2.9 (1.4 to 6.1) 0.004 Surgical complications

2.1 (1.1 to 4.3) 3.3 (1.6 to 6.9) 0.001

Aspiration 2.4 (1.4 to 3.9) 1.8 (1.0 to 3.3) 0.04 Pneumonia 1.7 (0.90 to 3.3) 1.8 (0.92 to 3.5) 0.07 Myocardial infarction

2.5 (0.2 to 28) 1.3 (0.7 to 27) 0.8

Postoperative infection

1.9 (0.7 to 5.0) 1.4 (0.5 to 4.0) 0.4

Cardiac complications

0.8 (0.43 to 1.4) 0.7 (0.37 to 1.3) 0.2

No. of patients needing to be referred to HVH to avoid one complication

Outcome variable Absolute Risk Reduction, %

Number needed to refer to HVH

Reintubation 19.2 5 Aspiration 18.0 6

Pulmonary failure 8.9 11 Renal failure 7.5 13

Surgical complications 7.1 14 Septicemia 4.7 21



Mortality: Overall mortality rate= 8.2% HVHs had a mortality rate of 2.5% versus 15.4% at LVHs (p<0.001) For elective cases only, mortality rate was 3.2% at HVHs c.f. 11.5% at LVHs (p=0.005) In multivariate analysis adjusting for significant patient covariates, surgery at LVH was associated with a near sixfold increased risk of death (OR,5.7; 95% CI, 2.0 to 16.0; p<0.001)

Outcome Variable Unadjusted odds

ratio (95% CI) Adjusted Odds Ratio (95% CI)

Adjusted p

Mortality 7.3 (2.7 to 19.3) 5.7 (2.0 to 16.0) <0.001 Length of stay: Median= 13 days (interquartile range=6-29 days)

Significant complications Odds Ratio 95% CI Pulmonary failure 6.8 2.7-17.5 Renal failure 41.5 11.9-144 Pneumonia 2.7 1.1-6.8 Postoperative infection 3.8 1.2-12.6 Reintubation 5.7 2.6-12.4 Septicaemia 8.2 2.5-26.9


Dimick (2005) United States of America This paper is likely to share some data covered by Dimick (2003)b Dimick (2003) and Dimick (2004)

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 8,657

Time Period 1(1988 to 1991) 2 (1992 to 1996) 3 (1997 to 2000) Total number, n(%) 1,963 3,663 3,031

Age:

Time Period 1(1988 to 1991) 2 (1992 to 1996) 3 (1997 to 2000) Age (Mean±SD) 63 (12) 63 (12) 63 (12)

Hospital Number: NR Surgeon Number: Sn = NA Volume Definitions: Hospital: Volume threshold for oesophageal resection >6 per year Surgeon: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1988 to 2000 Outcome Measures: In-Hospital Mortality Prolonged length of Stay Data Source: Nationwide Inpatient Sample data

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: ICD-9-CM: 42.40,42.41 and 42.42 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: Referral improved over time with proportion of oesophageal resections performed at HVHs increasing from 40% (1988-1991) to 57% (1997-2000) Covariates: Age:

Time Period 1(1988

to 1991)

2 (1992 to 1996)

3 (1997 to 2000)

Age (Mean±SD)

63 (12)

63 (12)

63 (12)

Inclusion criteria: NR


Dimick (2005) (Cont.) United States of America This paper is likely to share some data covered by Dimick (2003)b Dimick (2003) and Dimick (2004)

End Points: Morbidity: NR Mortality: Overall mortality rate= 11.3% Modest but significant decline from 13.6% to 10.5% (1988 to 2000) (p=0.001) Low volume hospitals had markedly higher mortality rates and showed no improvement over time (15.3% vs 14.5%) HVHs demonstrated a significant reduction in mortality over time 11.0% vs 7.5% (p=0.003).

Relationship of Mortality during three time periods for OR (Oesophageal Resection) Time Period

1(1988 to 1991) 2 (1992 to 1996)

3 (1997 to 2000) p value

Mortality (%) Overall 13.6 10.8 10.5 0.001 High volume hospitals

11.0 7.3 7.5 0.003

Low volume hospitals

15.3 14.7 14.5 0.8

In risk adjusted multivariate analysis, trend towards overall reduction in mortality for time period 2 (OR, 0.87; 95% CI, 0.7-1.1) and time period 3 (OR, 0.88; 95% CI, 0.7-1.2) but this did not reach statistical significance When only considering HVHs there was significant 42% reduction in mortality between time period 1 and time period 2 (OR, 0.58; 95% CI, 0.39-0.89; p=0.01)

Gender:

Time Period 1(1988

to 1991)

2 (1992 to 1996)

3 (1997 to 2000)

Female Gender, no.(%)

509 (26)

918 (25)

687 (22)

Race:

Time Period 1(1988

to 1991)

2 (1992 to 1996)

3 (1997 to 2000)

Nonwhite race, no.(%)

- 418 (15)

310 (14)

Comorbidities: n(%)

Time Period No. of Comorbid Conditions, No. (%)

1 (1988

to 1991)

2 (1992

to 1996)

3 (1997

to 2000)

0 251 (13)

501 (14)

424 (14)

1 743 (38)

1,364 (37)

1,177 (39)

2 839 (43)

1,456 (40)

1,144 (38)

≥3 130 (7)

342 (9)

286 (9)

Exclusion criteria:

NR


Dimick (2005) (Cont.) United States of America This paper is likely to share some data covered by Dimick (2003)b Dimick (2003) and Dimick (2004)

Length of stay:

Relationship of Prolonged LOS during three time periods for OR (Oesophageal Resection)

Time Period 1(1988 to 1991) 2 (1992 to

1996) 3 (1997 to 2000) p value

Overall 33 27 21 <0.001 High volume hospitals

33 23 20 <0.001

Low volume hospitals

33 32 23 <0.001

Median length of stay= 15 days (IQR, 11 to 24 days) Median LOS decreased over time from 17 days (IQR, 13 to 28 days) during time period 1 to 13 days (IQR 10 to 21 days) during time period 3 (p<0.001) Proportion of patients experiencing prolonged LOS (>75th percentile) showed significant decline from 33% during 1988-1991 to 21% during 1997-2000 (p<0.001) In risk-adjusted multivariate analysis, significant reduction in prolonged LOS for both time period 2 (OR, 0.73; 95% CI, 0.61-0.88) and time period 3 (OR, 0.59; 95% CI, 0.49-0.71) compared to time period 1


Time Period 1

(1988 to 1991)

2 (1992 to 1996)

3 (1997 to 2000)

Urgent Admission, no. (%)

233 (12)

339 (9)

238 (8)

Emergent Admission, No. (%)

357 (18)

548 (15)

311 (10)


Dimick (2005)b United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume Population Number: Pn = 1,946

Type of Surgeon Operation by Thoracic Surgeon General Surgeons Patients, n(%) 625 (32%) 1321 (68%)

Age:

Type of Surgeon Operation by Thoracic Surgeon General Surgeons Age>75y, n(%) 174 (27.8) 426 (32.3)

Hospital Number: NR Surgeon Number: Sn = 1118 (305, 27%, board certified in thoracic surgery) Volume Definitions: Hospital:

Low Volume Medium Volume High Volume Hospital Volume, cases per year

<5 5-12 >12

Relationship of Surgeon Board Certification and Hospital Volume

Hospital volume Thoracic Surgeons, No. (%) (n=305)

General Surgeons, No. (%) (n=813)

Low 67 (22.0) 240 (29.5) Medium 151 (49.5) 419 (51.5)

High 87 (28.5) 154 (18.9)

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1998-1999 Outcome Measures: In-Hospital Mortality (defined as death before discharge or within 30 days) Prolonged length of Stay Data Source: Medicare Provider Analysis Review File (MEDPAR database)

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: ICD-9-CM: 42.40, 42.41, 42.42 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:

Type of Surgeon Thoracic

Surgeons number of patients

General Surgeons number of patients

Age>75y, n(%)

174 (27.8) 426 (32.3)

Gender:




Female, n(%)

141 (22.6) 325 (24.6)

Inclusion criteria: Patients who underwent oesophagectomy specifically for cancer Exclusion criteria: Medicare beneficiaries younger than 65 years or older than 99 years Those enrolled in health maintenance organisations (approx 10%)


Dimick (2005)b (Cont.) United States of America

Surgeon:

Low Volume Medium Volume High Volume Surgeon Volume,

cases per year <2 2-5 >5

Relationship of Surgeon Board Certification and Individual Surgeon Volume

Surgeon volume Thoracic Surgeons, No. (%) (n=305)


Low 116 (38.0) 402 (49.9) Medium 117 (38.4) 297 (36.9)

High 72 (23.6) 106 (13.2) End Points: Morbidity: NR Mortality: After adjustment for patient characteristics, mortality rates were 37% (odds ratio, 1.37; 95% CI, 1.02 to 1.82) higher for surgeons without specialty training compared with thoracic surgeons (adjusted mortality 16.5% vs 12.4%; p=0.01)

Thoracic General Operative Mortality (%) 12.5 16.4

Low Volume Surgeon High Volume Surgeon

Operative Mortality (%) 24.3 11.4

Low Volume Hospital High Volume Hospital Operative Mortality (%) 20.7 10.7

Race:




Nonwhite, n(%)

60 (9.6) 142 (10.8)

Comorbidities: n(%):

Type of Surgeon No. of Comorbid Conditions, n (%)

Thoracic Surgeons number

of patients


Charlson score ≥ 3

n (%)

245 (42.2)

567 (46.1)

Location: NR Stage: NR Treatment: Oesophagectomy


Dimick (2005)b (Cont.) United States of America

Risk adjusted mortality for General Surgeons stratified for hospital volume




Risk-adjusted mortality

25.5 15.3 12.4

Risk adjusted mortality for Thoracic Surgeons stratified for hospital volume





17.1 13.7 10.6

Risk adjusted mortality for General Surgeons for surgeon volume Low volume

Surgeons Medium volume Surgeons

High volume Surgeons


21.4 15.7 11.8

Risk adjusted mortality for Thoracic Surgeons for surgeon volume Low volume

Surgeons Medium volume Surgeons

High volume Surgeons


16.9 14.3 9.9

Risk of Mortality with OCR for General vs Thoracic Surgeons after adjusting for patient characteristics, hospital volume and surgeon volume Risk Adjustment Increased risk of mortality w/ General vs

Thoracic Surgeons OR (95% CI)

Unadjusted 1.43 (1.08-1.90) Adjusting for patient characteristics 1.37 (1.02-1.82)

Adjusting for hospital volume 1.32 (1.00-1.75) Adjusting for surgeon volume 1.23 (0.92-1.63)

Type of Admission: n(%)

Time Period Thoracic



Urgent Admission, no. (%)

72 (11.6) 163 (12.4)

Emergent Admission, No. (%)

37 (6.0) 88 (6.7)


Elixhauser (2003) United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: NR Age:

Mean age (years) Low High 62.4 63.7

Hospital Number:

Number of US hospitals that are high and low volume Low High No. of Hospitals (%) 681 (95.9%) 29

Mean number of Procedures Performed

Low Volume High Volume 2 9

Surgeon Number: NA Volume Definitions: Hospital:

Hospital Volume Thresholds Low High <7 >7

Surgeon: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 2000 Outcome Measures: In-hospital mortality Data Source: Healthcare Cost and Utilization Project (HCUP), including NIS


Mean age (years) Low High 62.4 63.7

Gender: NR Race: NR



Criteria Elixhauser (2003) (Cont.) United States of America


Mean in-hospital mortality, percent adjusted Low High P significance 9.8 4.0 P<0.05

LVHs for oesophagectomy had mortality rates that were on average 1.5 times higher than those in high-volume hospitals. Length of Stay: NR

Comorbidities: n(%)

Mean number of comorbidities Low High 1.9 2.1

Type of Admission: NR Location: NR Stage: NR Treatment: Oesophagectomy



Finlayson (2003) United States of America


Total Low Medium High Total no. of Events

5282 1681 1774 1827

Age:

Hospital Volume Stratum Low Medium High Age>65y, n(%) 57.3 49.9 50.9

* Adjusted for age groups: <35 35-44 45-54 55-64 65-74 75-79 80-84 >85 Hospital Number:

Total Low Medium High Total no. of sampled hospitals

603 443 120 40

Surgeon Number: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1995-1997 Outcome Measures: Operative Mortality (Inpatient mortality) Data Source: Nationwide Inpatient Sample


Hospital Volume Stratum Low Medium High Age>65y, n(%)

57.3 49.9 50.9

* Adjusted for age groups: see earlier Gender:

Hospital Volume Stratum Low Medium High Sex, female, n(%)

21.8 20.9 25.3

Inclusion criteria: Patients who undertook one of eight cancer resections; only oesophagectomy data was included in this analysis Exclusion criteria: Medicare beneficiaries younger than 65 years or older than 99 years Those enrolled in health maintenance organisations (approx 10%)


Finlayson (2003) (Cont.) United States of America


Low Volume Medium Volume High Volume Hospital Volume, cases per year

<4 4-9 >9

Relationship of Surgeon Board Certification and Hospital Volume

Hospital volume Thoracic Surgeons, No. (%) (n=305)


Low 67 (22.0) 240 (29.5) Medium 151 (49.5) 419 (51.5)

High 87 (28.5) 154 (18.9) Surgeon: NA End Points: Morbidity: NR Mortality:

Observed operative mortality by hospital volume Low Medium High Operative Mortality,

% 15.0 13.8 6.5

Observed operative mortality for oesophagectomy by Hospital Volume and Age

Operative Mortality, % Adjusted odds ratios, high vs low volume

Low Volume High Volume Age<65y 9.17 4.82 0.49 (0.20, 1.20) Age≥65y 19.32 8.14 0.38 (0.24, 0.62)

Race:

Hospital Volume Stratum Low Medium High Race,black, n(%)

9.1 11.7 10.1

Comorbidities, n(%):

Hospital Volume Stratum Low Medium High Charlson comorbidity index, ≥3

42.3 38.8 42.7


Hospital Volume Stratum Low Medium High Admission Acuity, urgent-emergent

26.5 21.7 15.6

Other:

Hospital Volume Stratum Low Medium High Median income, ≤ $25,000

31.6 31.3 27.1


Goodney (2003) United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 1125 (1125, 84% from full hospital notes and 180, 16%, from abbreviated CIU notes) Age: NR Hospital Number: NR Surgeon Number: NA Volume Definitions: Hospital:

Very Low Low Medium High Very High Hospital volume, no. of cases

<2 2-4 5-7 8-19 >19

Surgeon: NA End Points: Morbidity: NR Mortality: NR

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1994-1999 Outcome Measures: 30-day Readmission Postoperative length of stay Data Source: MEDPAR

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: NR Gender: NR

Inclusion criteria: Patients undergoing one of 14 cardiovascular or cancer procedures, however, only oesophagectomy data was used in this analysis Exclusion criteria: Medicare patients enrolled in risk-bearing health maintenance organisations Patients <65 and >99


Goodney (2003) (Cont.) United States of America

Length of Stay:

Very Low Low Medium High Very High Postoperative length of stay (no. of days)

19.7 20.1 19.6 20.0 18.2

Mean length of stay for oesophagectomy was 19.6 days Readmission Rate:

Overall Very Low


Readmission rate (%)

18.4 19.1 17.9 18.2 18.4 18.7

Race: NR Comorbidities, n(%): NR Location: NR Stage: NR Treatment: Oesophagectomy



Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 518 Age: Mean (SD) 61.4 (12.0) Hospital Number: Hn = 52 non-federal acute care hospitals in state of Maryland Surgeon Number: Sn = NA Volume Definitions: Hospital: Procedures/year

Very low Low Medium High ≤10 11-20 21-50 >201


Overall Very low Low Medium High 8.9 15.1 14.8 9.3 3.1

Unadjusted Relative Risk

Overall Very low Low Medium High - 4.9 4.8 3.0 1.0

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1990-1997 Financial Outcome Measures: Mortality Data Source: Maryland Health Services Cost Review Commission Database

Condition: NR Procedure: Excision of the oesophagus ICD- 9 Classification: ICD-9-CM NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: 61.4 (12.0) Race: % Caucasian: 78.0 African American: 20.5 Sex: % Male: 74.5 Comorbidities: %

0 51.0 1 18.0 2 3.3 ≥3 27.8

Dartmouth-Manitoba adaptation of Charlson index

Inclusion criteria: This study examined six procedures. Patients included for excision of the oesophagus had an ICD-9-CM code of 42.40 Exclusion criteria: Numerous non-complex surgical procedures were excluded, including: 41.5 Total splenectomy 43.7 distal gastrectomy with Jejunum anastomosis 44.31 to 44.39 gastroenterostomy 45.71 to 45.79 Distal large bowel excision 45.90 to 45.95 intestinal anastomosis 46.01 to46.04 exteriorization Of the bowel 46.10 to 46.14 colostomy 52.51 to 52.59 distal pancreatectomy


Gordon (1999) (Cont.) The United States of America

Adjusted Relative Risk

Overall Very low Low Medium High - 3.8 4.0 2.4 1.0

Length of stay: NA

Cancer type: % Benign: 16.4 Malignant: 83.6 Treatment Type: NR Type of admission: % Elective: 62.9 Emergent/Urgent:: 37.1


Ho (2006) United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume Population Number: Pn = 10,023 Age: % of patients ≥75 increased over sample period 1.1%

Time Period 1988-1991 1992-1996 1997-2000 Age >75yr (%) 15.1 16.5 16.2

Hospital Number: Hn: NR Surgeon Number: Sn: NR Volume Definitions: Hospital:

Time Period 1(1988-1991) 2(1992-1996) 3(1997-2000) Mean Hospital Volume

3.2 3.5 3.8

Surgeon:

Time Period 1(1988-1991) 2(1992-1996) 3(1997-2000) Surgeon Volume 1.8 1.9 2.1

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1988-2000 (1988-1991) (1992-1996) (1997-2000) Outcome Measures: Inpatient mortality Postoperative length of stay Data Source: Statewide hospital discharge abstract files for Florida, New Jersey and New York

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: ICD-9-CM: 42.40, 42.41, 42.42, 43.99 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:

Time Period 1988-

1991 1992-1996

1997-2000

Age >75yr (%)

15.1 16.5 16.2

Gender: NR Race: NR

Inclusion criteria: Patients undergoing one of 6 cancer resections,, however, only oesophagectomy data was used in this analysis Exclusion criteria: Patients who did not have a cancer diagnosis code related to the procedure performed Records containing missing physician license numbers


Ho (2006) (Cont.) United States of America


Time Period 1988-1991 1992-1996 1997-2000

% of mortality 14.5 11.7 10.5 Largest decline in inpatient mortality (4.0%) occurred for oesophagectomy (14.5% to 10.5% over the sample period). Time periods 1 (1988-1991) and 2 (1992-1996) show odds ratios that represent time-specific differences for all patients regardless of hospital and surgeon volume

Adjusted OR for inpatient mortality according to time period, hospital volume and surgeon volume Adjusted Odds Ratio 95% CI 1992-1996 0.89 0.74-1.06 1997-2000 0.90 0.74-1.10 Hospital volume (ln) 0.93 0.84-1.04 Surgeon volume (ln) 0.80 0.71-0.90

Actual and predicted inpatient mortality associated with increases in provider volume Time Period 1988-1991 1997-2000 Annual hospital volume NA NA Annual surgeon volume 1.8 2.1 Actual in-hospital death (%)

14.5 10.5

Predicted in-hospital death (%)

13.9 13.5

Length of Stay: Used as regressor but NR

Comorbidities: n(%)

Time Period 1988-

1991 1992-1996

1997-2000

Charlson ≥3 (%)

55.8 53.0 49.1

Type of Admission:

Time Period 1988-

1991 1992-1996

1997-2000

Nonelective admission (%)

27.8 25.3 17.4

Location: NR Stage: NR Treatment: Oesophagectomy

Appendix C 4.1: Study design tables – Oesophagectomy (Continued)

Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Hollenbeck (2007) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 4,020 Age: Mean (95% CI) 63.3 (63.0 to 63.6) Hospital Number: Hn = NR Surgeon Number: Sn = NA Volume Definitions: Hospital:

Low High Mean 1.0 19.5 SD 0 5.9

Surgeon: NA End Points: Morbidity: NA Mortality:

Low High Oesophagectomy 14.9 4.8

Odds Ratio for Operative Mortality (Bottom vs. Top Decile)

Unadjusted OR

95% CI Adjusted OR

95% CI

Oesophagectomy 3.5 2.1 to 6.0 2.2 1.3 to 3.5

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1993-2003 Outcome Measures: Intraoperative death (Intraoperative surgical death, death during course of hospitalization) Prolonged length of stay (Patients whose length of stay was greater than the 90th percentile) Data Source: Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample (NIS)

Condition: Procedure: ICD- 9 Classification: Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Mean (95% CI) 63.3 (63.0 to 63.6) Race: %

White 62.1 African American 6.8

Hispanic 2.6 Other 2.4

Missing 24.2 Sex: Women % 23.7 Comorbidities: NR



Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Hollenbeck (2007) (Cont.) The United States of America

Mortality: C Statistic



Oesophagectomy 0.78 0.78 Length of stay: Prolonged Length of Stay

Low High Oesophagectomy 11.3 5.2


Unadjusted OR


Oesophagectomy

2.3 1.5 to 3.7 1.7 1.0 to 2.9

C Statistic



Oesophagectomy 0.71 0.71

Other: Admission type: % Urgent/ Emergent admission = 24.2 Insurance: % Medicare = 46.9 Private = 40.8 Other = 12.3


Table 62: Operative Mortality


Adjusted risk factor Lives Saved Lives saved per 100 000 US population

% 95% CI No. 95% CI

Oesophagectomy

420 49.7 22.4 to 66.4 339 153 to 453

0.12



Adjusted risk factor Earlier Discharges Earlier discharges per 100,000 US population

% 95% CI No. 95% CI

Oesophagectomy

420 37.9 -1.5 to 60.9 198 -8 to 319

0.07


Kuo (2001) United States of America


Hospital Volume Low High Average no. per hospital per year

1.1 28

Patients per group 519 674 % Patients per group 43.5 56.5

Age: Average overall age= 64.3

Age by Hospital Volume Group Low Volume High Volume P value Mean age ± SD 63.1± 11.3 65.8±11.1 <0.001

Hospital Number:

Hospital Volume Low High 61 3


Type of Volume Low Volume High Volume Hospital Volume <6 >6

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: January 1992- December 1999 Outcome Measures: Hospital mortality Days of intensive care Length of stay Discharge disposition Total Cost Data Source: Massachusetts Health Data Consortium

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: ICD-9-CM 42.4x, 42.52, 42.62, 43.5 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:

Age by Hospital Volume Group Low

Volume High Volume

P value

Mean age ± SD

63.1± 11.3

65.8±11.1 <0.001

Gender:

Gender by Hospital Volume Group Low

Volume High Volume

P value

Gender (Male), n(%)

501 (74)

381 (73)

NS

Inclusion criteria: Hospitals were included if they performed at least one oesophagectomy between 1992 and 1999 Malignancy


Kuo (2001) (Cont.) United States of America


Hospital mortality (%) 9.2 3.7 fold decrease (2.5) Odds ratio of death at LVH was 4.3 (95% CI, 2.3 to 7.7)

Length of Stay:

Low High Median length of stay 2 day decrease

Unadjusted and Adjusted Outcomes by Provider Volume Group Statewide Low Volume High Volume P value Mortality (%) 5.4 9.2 2.5 <0.001 Unadjusted odds ratio (95% CI)

- 3.9 (2.2-6.9) 1 <0.001


- 4.3 (2.3-7.7) 1 <0.001

Unadjusted and Adjusted Length of Stay by Provider Volume Group Statewide Low Volume High Volume P value Length of Stay (days)

Median (IQR) 14 (10-21) 15 (11-23) 13 (10-20) <0.001 Mean

Unadjusted 19.5 20.5 18.8 <0.001 Adjusted - 19.1 18.8 =0.88

Race:

Race by Hospital Volume Group Low

Volume High Volume

P value

Nonwhite n(%)

74 (11.0)

31 (6.0) 0.003

Comorbidities, n(%):

Comorbidities by Hospital Volume Group Low

Volume High Volume

P value

None 507 (75) 369 (71) NS 1 148 (22) 130 (25) NS 2 15 (2) 15 (3) NS ≥3 4 (1) 5 (1) NS

Type of Admission:

Admission by Hospital Volume Group Low

Volume High Volume

P value

Emergency, n(%)

37 (6) 54 (10) <0.001

Urgent 23 (3) 73 (14) <0.001 Elective 614

(91) 392 (76)

<0.001

Location: NR Stage: NR

Exclusion criteria: Patients who did not have a cancer diagnosis code related to the procedure performed Records containing missing physician license numbers



The median length of stay in HVHs= 13 days and 15 days in LVHs (p<0.001). Median length of stay in HVHs declined from 15 days (1992-1994) to 11 days (1998-2000) (p<0.001) Median length of stay in LVHs declined from 16 days (1992-1994) to 14 days (1998-2000) (p=0.01) Intensive Care Unit Stay: Overall, the median reduction for intensive care unit stay was 3 days.

Unadjusted and Adjusted Outcomes by Provider Volume Group Statewide Low Volume High Volume P value Length of ICU stay (days)

Median (IQR) 3 (1-6) 2 (1-4) 5 (2-9) <0.001 Mean

Unadjusted 6.3 8.4 4.6 <0.001 Adjusted - 9.6 4.6 =0.08


Criteria Lin (2006) Taiwan


Type of Volume Very

Low Low Medium High Very High

No. of Patients (%)

1354 (20.3)

1338 (20.1) 1382 (20.7) 1161 (17.4)

1439 (21.6)

Age:

Type of Volume Very


Mean age, y (SD)

59 (12) 60 (12) 59 (12) 59 (12) 60 (12)

Hospital Number:

Type of Volume Very


Hospital No.

84 13 7 4 3


Type of Volume Very


Volume Threshold

<78 78-135 136-235 236-346 >346

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: January 2000- December 2003 Outcome Measures: In-hospital mortality Data Source: Taiwan National Health Insurance Research Database

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: ICD-9-CM Training Hospital: Not examined as all regional hospitals are teaching hospitals Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:

Type of Volume Very

Low Low Medium High Very

High Mean age, y (SD)

59 (12)

60 (12)

59 (12) 59 (12)

60 (12)

Gender:

Type of Volume Very

Low Low Medium High Very

High Female (%)

16 19 20 14 15

Inclusion criteria: Patients underwent one of five cancer-related gastrointestinal resections, however, only oesophagectomy was used for this analysis


Lin (2006) (Cont.) Taiwan


Type of Volume Very


Mean No. of Procedures (SD)

16 (21) 103 (19) 197 (21) 290 (42) 480 (165)

Surgeon: NA End Points: Morbidity: NA Mortality:

Hospital Volume Very Low Low Medium High Very High Observed Mortality Rate (%)

6.79 7.60 5.31 4.22 5.49

Unadjusted odds ratio (95% CI)

1.00 1.13 (0.84-1.51)

0.77 (0.56-1.06)

0.60 (0.42-0.86)

0.80 (0.58-1.09)


1.00 0.97 (0.68-1.39)

0.87 (0.62-1.23)

0.72 (0.47-0.91)

0.65 (0.43-0.97)

Length of Stay: NR

Race: NR Comorbidities, ≥3%;

Type of Volume Very Low


75 80 79 78 76 Type of Admission: NR Location: NR Stage: NR Treatment: Oesophagectomy



Miller (1997) Canada

Hospital Volume and/or Surgeon Volume: Surgeon Volume Population Number: Pn = 74

Operated on by Occasional Surgeon Operated on by Frequent Surgeon 32 42

Age: Hospital Number: Hn = NA Surgeon Number: Sn = 20 Volume Definitions: Hospital: NA Surgeon:

Occasional Surgeon Frequent Surgeon ≤5 ≥6

End Points: Morbidity:

Occasional Frequent Anastamotic Leaks, n (%) 7 (22) 3 (7)

Mortality:

Occasional Frequent Operative Deaths, n (%) 7 (22) 0

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1989-1993 Outcome Measures: Inpatient Mortality Data Source: Hamilton Regional Cancer Centre (HRCC)

Condition: NR Procedure: Oesophagectomy ICD- 9 Classification: ICD-9-CM NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: NR Race: % NR Sex: % NR Comorbidities: % NR Cancer type: % NR Treatment Type: NR



Miller (1997) (Cont.) Canada

Type of admission: % NR Tumour Site:

Occasional Frequent Middle 2 11 Lower 11 14 Gastroesophageal junction

19 17


Patti (1998) United States of America


No. of Patients (%) Very Low Low Medium High Very High 453 (29) 320 (21) 291 (19) 224 (14) 273 (17)

Age:

Age (yr) No. of Patients 0-34 14

35-54 279 55-64 412 65-75 587 >75 269

Hospital Number: Hn = 133 hospitals (during years of study)

No. of Hospitals (%) Very Low Low Medium High Very High 196 (72) 43 (16) 20 (7) 9 (3) 5 (2)


Hospital Volume in Quintiles per 5 years Very Low Low Medium High Very High

1-5 6-10 11-20 21-30 >30 Category applied by reviewer Surgeon: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1990-1994 Outcome Measures: Inpatient Mortality Data Source: Office of Statewide Health Planning and Development (OSHPD)

Condition: NR Procedure: Oesophagectomy ICD- 9 Classification: ICD-9-CM NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:

Age (yr) No. of Patients 0-34 14 35-54 279 55-64 412 65-75 587 >75 269

Race: %

White 1235 Hispanic 120 Asian 93 Black 89 Native American 2 Other 14 Unknown 8



Patti (1998) (Cont.) United States of America

End Points: Morbidity: Incidence of postoperative complication

Complication (%)


Infection 8 9 9 7 9 haemorrhage 4 5 3 4 7

Mortality: Crude Mortality Rate (%)


Note: terminology of categories applied by reviewer Adjusted Odds Ratio (95% CI)


Note: terminology of categories applied by reviewer Length of stay (days):


Sex: %

Male 1213 Female 348

Comorbidities: % NR Cancer type: % NR Treatment Type: NR Type of admission: % NR Tumour Site:

Upper 126 Middle 163 Lower 1115 Other 157


Authors Procedure Study Design Study Variables Inclusion/Exclusion Criteria Rouvelas (2007) Sweden

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn =1,199

Low Volume High Volume 731 (61) 468 (39)

Age:



Low Volume High Volume 51 2

Surgeon Number: Sn = NA Volume Definitions: Hospital: Number of procedures performed annually during study period

Low Volume High Volume <10 >10


Level of Evidence: Prospective Follow-up: From the date of surgery till death emigration or the end of the study (October 2004). Lost to Follow-up: NR Study Period: 01/01/1987 – 31/12/2000 Outcome Measures: Mortality: 30 day, 1,3 and 5 years Data Source: National cancer register accessed through an inpatient register, based on patients national registration number.

Condition: Oesophageal cancer Procedure: Most common approach was transthoracic Oesophageal resection ICD- Xx Classification: NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:


Race: NR

Inclusion criteria: ▪ Only adenocarcinomas and

squamous cell carcinomas of the oesophagus were included.

Exclusion criteria: ▪ NR


Authors Procedure Study Design Study Variables Inclusion/Exclusion Criteria Rouvelas (2007) Sweden

See Table 64: Tumour stage survival duration specific mortality rates Basic and adjusted hazard ratios

Hospital volume category

All patients Patients without preoperative Oncological treatment

HR (95% CI) P Value HR (95% CI) P Value Low volume 1.00 … 1.00 … High volume Crude model

0.89 (0.78-1.01)

0.08 0.92 (0.78-1.08)

0.30

High volume Basic model

0.88 (0.77-0.99)*

0.047 0.91 (0.77-1.07)*

0.26

High volume Adjusted model

0.90 (0.79-1.04)†

0.16 0.99 (0.84-1.18)‡

0.99

* Adjusted for age and sex † Adjusted for age, sex, comorbidity, tumour location, tumour type, calendar period, and preoperative oncologic treatment ‡ Adjusted for age, sex, comorbidity, tumour location, tumour type, calendar period and tumour stage

Comorbidities:

Comorbidities Low Volume

High Volume

0 472 (64.6)

363 (77.6)

1 132 (18.1)

57 (12.2)

>1 118 (16.1)

26 (5.6)

No data 9 (1.2) 22 (4.7) Cancer Stage

Stage Low volume

High volume

1 67 (14.8)

50 (16.1)

2 180 (39.7)

112 (36.0)

3 142 (31.3)

112 (36.0)

4 50 (11.0)

37 (11.9)

Undefined 14 (3.1) 0 Cancer location

Low volume

High volume

Upper 31 (4.2)

28 (6.0)

Middle 144 (19.7)

121 (25.9)

Lower 506 (69.2)

309 (66.0)

Missing data 50 (6.8)

10 (2.1)


Authors Procedure Study Design Study Variables Inclusion/Exclusion Criteria Rouvelas (2007) (Cont.) Sweden

Length of stay: NR

Cancer type

Low volume

High volume

Squamous cell

429 (58.7)

308 (65.8)

Adenocarcin – oma

215 (29.4)

123 (26.3)

Uncertain 87 (11.9)

37 (7.9)

Previous treatment

Low volume

High volume

No 453 (62.0)

311 (66.5)

Yes 243 (33.2)

148 (31.6)

Missing data 35 (4.8)

9 (1.9)

Date of procedure

Low volume

High volume

1987-1991 224 (30.6)

164 (35.0)

1992-1996 290 (39.7)

153 (32.7)

1997-2000 217 (29.7)

151 (32.3)


Swisher (2000) United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 340 Age: Mean (SD) NR Hospital Number: Hn = 25 hospitals 13 national cancer institutions and 88 community hospitals Surgeon Number: Sn = NA Volume Definitions: Hospital:

Oesophageal Operative Volume Low High

<5 cases per year ≥5 cases per year

Total Operative Volume Low High

<3333 cases per year ≥3333 cases per year

Bed Size Low High

<600 beds ≥600 beds

Cancer Specialisation National cancer institution Community Hospital

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1994-1996 Outcome Measures: Mortality Morbidity Length of Stay Data Source: Health Care Utilization Project (HCUP)

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: ICD-9-CM NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: NR Race: % NR Sex:

No. % Male 265 78 Female 75 22

Comorbidities: % NR

Inclusion criteria: ▪ Oesophagectomies based

on ICD-9 procedure and diagnosis codes

Exclusion criteria: * Those patients with oral or pharyngeal tumours


Swisher (2000) (Cont.) United States of America

Surgeon; median (range; interquartile range): 10 (1-40; 6-19)

Surgeon Volume according to quartiles Very Low Low Medium High Difference in surgeons’ surgical volumes

1 10 20 40


No. of Hospitals Patients Actual Complications of Care, No of patients (%)

Cancer specialisation

NCIs 12 310 176 (57%) Community

Hospitals 13 30 21 (70%)

P value NS Oesophagectomy volume

≥5 cases/year 5 266 147 (55%) <5 cases/year 20 74 50 (68%)

P value 0.06 Total Operative Volume

≥3333 cases/year 10 262 150 (57%) <3333 cases/year 15 77 47 (61%)

P value NS Hospital Size

≥600 beds 12 176 104 (59%) <600 beds 13 164 93 (57%)

P value NS

Cancer type: % NR Treatment Type:

No. of Patients

%

Total Oesophagectomy

133 39

Partial Oesophagectomy

196 58

Not otherwise specified

11 3

Type of admission: % NR Location of Tumour:

No. of patients

%

Cervical Oesophagus

6 2

Upper Oesophagus

17 5

Middle Oesophagus

38 11

Lower Oesophagus

227 67

Not otherwise specified

52 15



End Points: Mortality:

No. of Hospitals Patients Actual Mortality Cancer specialisation

NCIs 12 310 12 (4.2%) Community

Hospitals 13 30 4 (13.3%)

P value 0.05 Oesophagectomy volume

≥5 cases/year 5 266 8 (3.0%) <5 cases/year 20 74 9 (12.2%)

P value 0.004 Total Operative Volume

≥3333 cases/year 10 262 12 (4.6%) <3333 cases/year 15 77 5 (6.5%)

P value NS Hospital Size

≥600 beds 12 176 12 (6.8%) <600 beds 13 164 5 (3.0%)

P value NS



Multivariate Analysis of operative mortality in hospitals per operative volume, hospital size or cancer specialisation

Hospital Factors Odds Ratio CIs P value Cancer specialisation (community hospitals)

0.98 0.23-4.26 .98

Oesophagectomy volume (<5 cases/yr)

3.97 1.14-13.84 .03

Total operative volume (<3333 cases/year)

1.96 0.32-12.3 .47

Hospital size (<600 beds)

0.25 0.05-1.31 .10

Length of stay:

No. of Hospitals Patients Actual Length of Stay, Mean (95%CI)

Cancer specialisation

P=0.002

NCIs 12 310 14.9 (14.1-15.8) Community

Hospitals 13 30 20.2 (16.1-25.6)

Oesophagectomy volume

P=0.006

≥5 cases/year 5 266 14.7 (13.9-15.6) <5 cases/year 20 74 17.7 (15.6-202)

Total Operative Volume

p=0.017

≥3333 cases/year 10 262 14.8 (13.9-15.7) <3333 cases/year 15 77 17.4 (15.2-19.8)

Hospital Size p<0.05 ≥600 beds 12 176 14.1 (13.0-15.2) <600 beds 13 164 16.8 (15.6-18.2)


Criteria Urbach (2003) Canada Data set is same as that used in Urbach (2004) and Urbach (2005)


Average annual hospital volume Quartile 1 Quartile 2 Quartile 3 Quartile 4 No. of Patients

161 167 108 177

Age:

Average annual hospital volume Quartile 1 Quartile 2 Quartile 3 Quartile 4 Mean age (and SD), yr

65.2 (10.2) 63.7 (10.0) 65.0 (10.9) 63.4 (11.6)

Hospital Number:

Average annual hospital volume Quartile 1 Quartile 2 Quartile 3 Quartile 4 No. of Hospitals

37 6 2 2

Surgeon Number: NA Volume Definitions: Hospital: NR Surgeon: NA

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: Apr 1 1994 to Mar 31 1999 Outcome Measures: 30 day mortality Lives Saved Data Source: Canadian Institute for Health Information (CIHI) and Ontario Registered Persons Database (RPDB)

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: NR CCP Procedure Code: 54.33 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age:

Average annual hospital volume Quartile

1 Quartile 2

Quartile 3

Quartile 4

Mean age (and SD), yr

69.5 (11.1)

68.6 (11.7)

68.7 (11.6)

68.4 (11.8)

Gender:


1 Quartile 2

Quartile 3

Quartile 4

% male

69.6 73.7 73.2 76.8

Inclusion criteria: Patients underwent one of five cancer-related gastrointestinal resections, however, only oesophagectomy was used for this analysis


Criteria Urbach (2003) (Cont.) Canada Data set is same as that used in Urbach (2004) and Urbach (2005)


Risk of 30 day mortality, according to hospital volume quartile Quartile 1 Quartile 2 Quartile 3 Quartile 4 P value for

trend No. of deaths

30 21 13 18

Risk of death (%)

18.6 12.6 12.0 10.2 0.03

Adjusted relative risk of death (and 95% CI)

1.9 (1.0,3.7)

1.3 (0.6, 2.5)

1.1 (0.5, 2.4)

1.0 0.04

Overall mortality rate for oesophageal resection is 13.4%. Potentially Avoidable Deaths:

Potentially avoidable deaths (per year)

No. of persons

No. of deaths

Risk of death, %

Point estimate (and 95% CI)

% of all deaths (and 95% CI)

Oesophagectomy 613 82 13.4 4 (0,9) 24.3 (0, 54.9)

Annual no. of lives saved by regionalisation at HVHs was 4 (95% CI, 0-9) for oesophagectomy.

Race: NR Comorbidities, n(%):


1 Quartile 2

Quartile 3

Quartile 4

Mean Charlson Score (and SD)

3.9 (2.2)

4.5 (2.2)

4.4 (2.2)

4.0 (2.3)

Type of Admission: NR Location: NR Stage: NR Treatment: Oesophagectomy



Urbach (2004) Canada Data set used same as Urbach (2003;2005)

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 613 Age: Mean (SD) age in years= 64.2 (10.7) Hospital Number: No. of hospitals= 47 Surgeon Number: NA Volume Definitions: Hospital: Median (interquartile range) for average annual hospital volume: 8.8 (2.8-16.6) Range: 0.2-19.0

Type of Volume Low Volume Hospitals High Volume Hospitals Volume Threshold <8.8 >8.8


30 day mortality according to hospital volume Low Volume

No. (%) High Volume No. (%)

Crude odds ratio (95% CI)


Oesophagectomy 51/328 (15.55)

31/285 (10.88)

0.66 (0.41 to 1.07)

0.60 (0.30 to 1.20)

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: Apr 1 1994 to Mar 31 1999 Outcome Measures: 30 day mortality Data Source: Ontario Health Database

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Mean (SD) age in years= 64.2 (10.7) Gender: No. (%) male= 450 (73.4) Race: NR Comorbidities, n(%): Median (Interquartile range) Charlson score= 4 (2-6) Type of Admission: NR Location: NR





Length of Stay: NR

Stage: NR



Hospital Volume and/or Surgeon Volume: Hospital Volume and Surgeon Volume Population Number: Pn = 613

Average Annual hospital volume Quartile 1 Quartile 2 Quartile 3 Quartile 4 Number of subjects

156 170 151 136

Average Annual Surgeon volume Quartile 1 Quartile 2 Quartile 3 Quartile 4 Number of subjects

163 156 159 135

Age: NR Hospital Number:

Average Annual hospital volume Quartile 1 Quartile 2 Quartile 3 Quartile 4 No. of hospitals

45 8 3 2

Total number= 58 Surgeon Number:

Average Annual Surgeon volume Quartile 1 Quartile 2 Quartile 3 Quartile 4 No. of Surgeons

66 17 8 2

Total number= 93

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: April 11994- March 31 1999 Outcome Measures: 30 day mortality Postoperative length of stay Data Source: Canadian Institute for Health Information (CIHI), Ontario health Insurance Plan (OHIP) and Registered Persons Database (RPDB)

Condition: Oesophageal Cancer Procedure: Oesophagectomy ICD- 9 Classification: NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Adjusted not reported Gender: Adjusted not reported




Urbach (2005) (Cont.) Canada Data set used same as Urbach (2003;2004)


Average annual hospital volume Quartile 1 Quartile 2 Quartile 3 Quartile 4 Volume thresholds

0.2-2.1 2.2-7.0 7.1-12.0 12.1-14.4

Surgeon:

Average annual surgeon volume Quartile 1 Quartile 2 Quartile 3 Quartile 4 Volume thresholds

0.6-2.3 2.4-4.5 4.6-6.8 6.9-15.8


Average annual hospital volume: Quartile 1 Quartile 2 Quartile 3 Quartile 4 Number of deaths (30 day)

29 18 22 13

Risk of death, %

18.59 10.59 14.57 9.56

Overall risk of death within 30 days= 13.4%

Average annual surgeon volume: Quartile 1 Quartile 2 Quartile 3 Quartile 4 Number of deaths (30 day)

29 16 28 9

Risk of death, %

17.79 10.26 17.61 6.67

Surgeon random effect for 30-day mortality=0.540 and standard error of variance=0.424 Hospital random effect for 30-day mortality=0.119 and standard error of variance= 0.311

Race: NR Comorbidities, n(%): Adjusted not reported Type of Admission: NR Average annual Surgeon Volume Quartile: Adjusted not reported Average annual Hospital Volume Quartile: Adjusted not reported Location: NR Stage: NR Treatment: Oesophagectomy


Urbach (2005) (Cont.) Canada Data set used same as Urbach (2003;2004)

Length of Stay:

Average annual hospital volume: Quartile 1 Quartile 2 Quartile 3 Quartile 4 Median 16 16 16 15.5 Interquartile range

12-22.5 11-27 12-25 13-23.5

Average annual surgeon volume: Quartile 1 Quartile 2 Quartile 3 Quartile 4 Median 17 16 16 15 Interquartile range

13-27 13-26 12-25 12-22

Surgeon random effect for length of stay=0.025 and standard error of variance=0.026 Hospital random effect for length of stay=0.008 and standard error of variance= 0.019


Van Lanschot (2001) The Netherlands

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn DNMR= 1792 Pn DNNDP= 1900

Hospital volume Low Medium Medium and

Low volume combined

High

1-10 11-20 >20 No. of procedures (%) DNMR

928 (52) 107 (6) 1035 (58) 757 (42)

No. of procedures (%) DNNDP

- - 1214 (64) 686 (36)

Age:

Age according to DNNDP Low/Median

Volume n=1214 (%)

High Volume n=686 (%)

p-value

Age 62±11 63±22 0.13 Hospital Number: Hn=NR Surgeon Number: Sn=NA Volume Definitions: Hospital:

Average annual hospital volume Low Medium High

Volume thresholds 1-10 11-20 >20

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 1993-1998 Outcome Measures: 30 day mortality Data Source: Dutch National Medical Registry (DNMR) and Dutch Network and National Database for Pathology (DNNDP)


Age according to DNNDP Low/Median

Volume n=1214 (%)


p-value

Age 62±11 63±22 0.13

Inclusion criteria: Patients who underwent oesophagectomy - followed by reconstruction with a gastric tube or colon interposition - with additional procedures not otherwise described



Criteria Van Lanschot (2001) (Cont.) The Netherlands


Average annual hospital volume: Low Medium High Hospital Mortality 12.1% 7.5% 4.9%

There is a significant (inverse) relation between hospital volume and hospital mortality, decreasing from 12.1% in LVHs to 7.5% in MVHs and 4.9% in HVHs (p<0.001) Length of Stay: NR

Gender:

Gender according to DNNDP Low/Median

Volume n=1214 (%)


p-value

Sex (male/ female)

890/324 498/188 0.20

Race: NR Comorbidities, n(%): NR Type of Admission: NR Location: NR Stage:

pTNM Low Volume, n (%)

High Volume, n (%)

Stage 1 140 (13) 78 (13) IIa 327 (29) 149 (24) IIb 89 (8) 45 (7) III 506 (46) 288 (46) IV 49 (4) 61 (10)


Criteria Van Lanschot (2001) (Cont.) The Netherlands

Cancer Type:

LVH HVH Adenocarcinoma 741 (61) 398 (58) Squamous cell carcinoma

370 (31) 223 (33)

Other: 103 (8) 65 (9)

Appendix C 4.2: Volume outcome tables – Oesophagectomy Authors Volume outcome data

Bachmann (2002) United Kingdom

There was a general trend in the adjusted odds ratio, according to surgeon volume, from very low to high for 30-day mortality (OR= 0.95 (95% CI= 0.90-1.00)) and OR=0.14 (95% CI= 0.03-0.63), respectively. Operative mortality decreased with increase surgeon volume (p=0.01) Operative mortality decreased with increase hospital volume (p=0.057)



Decreasing mortality with increasing volume leads to P<.001 for oesophagectomy 30-day mortality decrease from 17.3% (95% CI, 13.3-22.0%) in low volume category to 3.4% (95% CI, 0.7%-9.6%) in highest volume category.



When treated as a continuous variable hospital volume is significantly associated with patient mortality p<0.001



Surgeon volume was inversely related to operative mortality (P<0.001) and accounted for 46% of the apparent effect of hospital volume for esophagectomy For oesophagectomy, operative mortality among patients treated by low-volume surgeons at high-volume hospitals was higher than the overall operative mortality at low-volume hospitals (17.5% vs 11.1% respectively)

Appendix C 4.2: Volume outcome tables – Oesophagectomy (continued) Authors Volume outcome data


Total lives saved by new EHR (evidence-based hospital referral) standards= 180 for esophagectomy This was determined by estimating the population at risk and then accounting for mortality associated with each procedure and the potential reductions associated with each volume, process or outcomes standard. EHR standard for esophagectomy was ≥13



Historical mortality did not predict subsequent mortality for oesophagectomy, however, procedure volume did (P<0.001). Procedure volume predicted subsequent mortality considerably better than historical mortality (difference of 12.5% for volume, 17.5% to 20.5%; best to worst, but only 1.5%, 11.4% to 12.9%, across quintiles of historical mortality)

* too small to determine

Prediction of Mortality Rates (1998-1999) by Historical Volume Odds of subsequent Mortality, Worst vs. Best (95% CI) Proportion of Variation Explained

Oesophageal Cancer Resection 1.18 (0.75-1.89) *

Prediction of Mortality Rates (1998-1999) by Procedure Volume Odds of subsequent Mortality, Worst vs. Best (95% CI) Proportion of Variation Explained

Oesophageal Cancer Resection 3.09 (1.90-5.02) *



There was a significant difference between the % adjusted in-hospital mortality rate for LVHS and HVHs (9.8 vs 4.0% respectively, p<0.05)



Unadjusted in-hospital mortality rates were lower in high volume hospitals (2.7%) than medium (12.7%) and low (16%) volume hospitals (p<0.001) High hospital volume was associated with: 1) fivefold reduction in risk of death (odds ratio, 0.21; 95% confidence interval, 0.10 to 0.42; p<0.001_ 2) 6-day (95% confidence interval, 5 to 7 days; p<0.001) reduction in length of stay; and 3) $11,673 (95% confidence interval, $9,504 to $12,841; p<0.001) decrease in hospital charges High Volume Hospitals had a significant reduction in LOS (P<0.001), compared to Low Volume Hospitals; 6 days (95% CI; 5-7 days)



Rate of postoperative complication were 44% for oesophageal resection (range 30% to 51% across volume deciles, P=0.03) Oesophageal resection at HVH, in comparison to LVH, had lower rates of aspiration, pulmonary failure, renal failure, septicaemia and surgical complications Morbidity:

Complication Rate at high-volume hospital

Rate at low-volume hospital

Adjusted OR (95% CI)

Adjusted P value

One or more complications

39% 48% 0.68 (0.52 to 0.90)

0.008

Aspiration 12.7% 18.1% 0.67 (0.52 to 0.91)

0.008

Cardiac complications

8.6% 9.5% 0.99 (0.61 to 1.63)

0.9

Postoperative infection

2.7% 3.3% 0.77 (0.36 to 1.67)

0.5

Pneumonia 5.4% 5.7% 0.77 (0.43 to 1.35)

0.3

Pulmonary failure

7.8% 12.1% 0.57 (0.38 to 0.87)

0.008

Renal failure 1.9% 5.4% 0.36 (0.16 to 0.83)

0.016

Septicemia 3.6% 7.1% 0.52 (0.28 to 0.96)

0.036

Surgical Complications

10.0% 12.0% 0.70 (0.45 to 1.0)

0.08


Dimick (2003b) United States of America

The operative mortality rate varied more than 3-fold across hospital volume groups (11.8% to 3.7%; p=0.001). In comparison to VHVH both medium and low volume hospitals were reported as significantly associated independent variable, p=0.002 and p<0.001 respectively. Prolonged length of stay (>75th percentile of patient length of stay) was significantly more likely at low volume hospitals than very high volume hospitals p<0.001.

Variation in Operative Mortality Rates Across Hospital Volume Quartiles for Patient Subgroups undergoing Oesophageal Resection, % Annual Hospital Volume Overall Low <3 Medium 3-5 High 6-16 Very High >16 P value Nature of Admission

Elective 6.7 9.6 9.7 3.9 3.4 <0.001 Urgent or Emergent 15.2 21 11.4 14.9 5.3 0.006

Patient Age, y <60 5.3 8.3 7.6 3.7 1.7 0.001

60-69 7.6 10.9 8.5 4.9 5.8 0.04 70-79 11.8 13.1 16.3 12.2 4.4 0.007 ≥80 15.6 26.5 12 6.5 3.3 0.008

Indication for surgery Malignant 8.1 11.9 10.3 5.6 4.1 <0.001

Benign 8.7 11.4 10.3 10.7 1.8 0.02


Dimick (2003c) United States of America

Hospital volume varied significantly from 2.5% at HVH to 15.4% at LVHs (p<0.001). However this level of significance changed when only elective cases were included, 3.2% at HVHs and 11.5% at LVHs (p=0.001)



Low volume hospitals had higher mortality rates and showed no improvement over time (15.3% vs 14.5%) whereas HVHs demonstrated significant reduction in mortality over time (11.0% vs 7.5%, p=0.003) When considering hospital volume, both high (33% to 20%, p<0.001) and low volume hospitals (33% to 23%, p<0.001) showed a decline in the proportion of patients with prolonged LOS As a result of multivariate analysis patients treated at LVHs had an almost 6 fold increase in risk of death (OR, 5.7, 95% CI 2.0 to 16.0; p<0.001)


Dimick (2005)b United States of America

Differences in mortality between high-volume and low-volume hospitals (10.7% vs 20.7%; p<0.001) and surgeons (11.4% vs. 24.3%; p<0.001) were larger than those between thoracic and general surgeons. After adjusting risk of mortality for general vs thoracic surgeons by hospital volume, a significant association existed, however after adjusting for surgeon volume the relationship was no longer significant (odds ratio, 1.23; 95% CI, 0.92 to 1.63) After adjustment for patient characteristics, mortality rates were 37% (odds ratio, 1.37; 95% CI, 1.02 to 1.82) higher for surgeons without specialty training compared with thoracic surgeons (adjusted mortality 16.5% vs 12.4%; p=0.01)



There was a significant difference between the % adjusted in-hospital mortality rate for LVHS and HVHs (9.8 vs 4.0% respectively, p<0.05)


Finlayson (2003) United States of America

Differences in operative risks (mortality) between low and high volume hospitals was statistically significant for oesophagectomy (15.0% vs 6.5%) For older adults (≥65 years) absolute difference in operative mortality between high and low volume hospitals was 11.18 (OR=0.38) and 4.35 for younger adults (<65 years) (OR=0.49)


Goodney (2003) United States of America

Hospital volume was reported as being significantly related to patient length of stay.


Gordon (1999) (Cont.) United States of America

There appears to be a general trend for mortality from very low hospital volume to high volume (15.1% to 3.1%). The difference between continuums decreased when the data was adjusted for hospital and patient characteristics (very low= 3.8 vs high=1.0).

Unadjusted Relative Risk Overall Very low Low Medium High NA 4.9

(2.0 – 11.5) P<0.001

4.8 (1.9-12.0) P<0.001

3.0 (1.1-8.3) P<0.05

1.0

Adjusted Relative Risk Overall Very low Low Medium High NA 3.8

(1.6-9.1) P<0.01

4.0 (1.5-10.1) P<0.01

12.4ns (0.9-6.7)

1.0


Ho (2006) (Cont.) United States of America

There was a significant decline in inpatient mortality for oesophagectomy (14.5% to 10.5%) between 1988 and 2000. Time periods 1 (1988-1991) and 2 (1992-1996) show odds ratios that represent time-specific differences for all patients regardless of hospital and surgeon volume Length of stay data was used as a regressor, however, was not reported.

Authors Volume Outcome Relationship Hollenbeck (2007) The United States of America

There was a substantial difference between mortality rates at LVHs and HVHs for oesophagectomy (14.9% and 4.8%, respectively) Adjusted mortality 2.2 (95% CI, 1.3-3.5) between lowest and highest volume decile. Unadjusted mortality 3.5 (95% CI, 2.1-6.0) between lowest and highest volume decile. Adjusted prolonged length of stay 1.7 (95% CI, 1.0-2.9) between lowest and highest volume decile. Unadjusted prolonged length of stay 2.3 (95% CI, 1.5-3.7) between lowest and highest volume decile.



Hospital mortality was significantly associated with volume (p<0.001) and 3.7 times higher among patients from LVHs (9.2%) when compared with patients from HVHs (2.5%). Significant difference in mortality after adjustment for confounders: age, race, comorbidity score, urgency of admission, source of admission, year, payer type and residence. Length of stay averaged 18.8 days for HVHs c.f. 20.5 for LVHs and was insignificant after adjusting for confounders Median length of ICU stay was significantly lower at HVHs (2 days) compared with LVHs (5 days) (p<0.001), however, after adjusting for confounders was close to significant (p=0.08) Patients > 65 years mortality rate was between HVH and LVH was greater (11.4% vs 2.7%, p<0.001).


Lin (2006) Taiwan

Very high hospital volume, after adjusting for patient and hospital characteristics, had a 35% probability of procedural survival (Adjusted OR of .65 (95% CI= 0.43-0.97) Total in-hospital mortality rate for oesophagectomy was 5.93% The adjusted odds ratio for oesophagectomy showed a steady mortality rate decline with increasing hospital volume (OR: very low= 1.00, low= 0.97 (0.68-1.39), medium= 0.87 (0.62-1.23), high=0.72 (0.47-0.91) and very high= 0.65 (0.43-0.97)).


Miller (1997) Canada

Out of 74 patients undergoing oesophagectomy, overall mortality was 9.5%. For the 32 patients operated on by occasional surgeons, there were 7 (22%) anastomotic leaks and 7 (22%) operative deaths. For the 42 patients operated on by frequent surgeons, there were 3 (7%) anastomotic leaks and 0 deaths. The anastomotic leak rates were not statistically significant (p<0.07) but frequent surgeons had a significantly lower operative mortality (p<0.0014)


Patti (1998) United States of America

There was no difference in the rates between hospital volumes, when examining length of hospital stay. The incidence of morbidity (post-operative complications) did not significantly differ between hospital volume categories. Crude operative mortality rates decreased from 18% to 5% (p<0.001) Risk adjusted mortality was reported at 17% VLVH, 19% LVH, 10% MVH, 16% HVH, 6% VHVH, (p<0.001)


Rouvelas (2007) Sweden

30 day Mortality 1 year Mortality 3 years Mortality 5 years Tumour stage Low Volume High Volume Low Volume High Volume Low Volume High Volume Low Volume High Volume All stages 411 (90.7) 297 (95.5) 246 (54.3) 179 (57.7) 138 (30.4) 105 (34.0) 110 (24.4) 81 (26.3) 1 64 (94.4) 48 (95.4) 57 (84.0) 43 (84.3) 49 (72.4) 34 (67.2) 43 (63.2) 31 (61.3) 2 163 (90.6) 106 (93.8) 115 (63.5) 72 (64.2) 66 (36.3) 45 (39.7) 54 (30.0) 33 (29.8) 3 131( 91.8) 107 95.0 55 (38.7) 51 (45.4) 16 (10.7) 19 (16.7) 10 (6.5) 11 (9.6) 4 43 (85.2) 36 (96.2) 15 (29.2) 13 (35.5) 6 (11.4) 7 (18.6) 2 (4.0) 6 (15.1) Undefined 10 (67.9) 0 4 (28.6) 0 1 (7.1) 0 1 (7.1) 0


Swisher (2000) United States of America

For operative mortality, there was a near statistically significant different between National Cancer Institutions and community hospitals (4.2% vs 13.3%) p=0.05. There was a significant difference between low and high volume of oesophagectomies (12.2% vs 3.0%, respectively) p=0.004, however there were no significant differences in low and high total operative volume or between low and high hospital size. For complications of care, there was a near significant difference in oesophagectomy volume between low and high volume (68% vs 55%, respectively) p=0.06. For the three other conditions (cancer specification, total operative volume and hospital size) there were no statistical differences. After multivariate analyses, accounting for hospital and patient characteristics, oesophagectomy volume remained significant, p=0.03. This showed that oesophagectomy volume was the only significant independent risk factor for mortality. For length of stay, all conditions exhibited statistically significant differences. For cancer specialisation length of stay was equal to 14.9 days (95% CI 14.1-15.8) for NCIs and 20.2 (95% CI 16.1-25.6) for community hospitals p=0.002, for oesophagectomy volume length of stay was equal to 14.7 days (95% CI 13.9-15.6) for high volume and 17.7 days (95% CI 15.2-19.8) for low volume, p=0.006, for total operative volume length of stay was 17.4 days (95% CI, 15.2-19.8) for low volume and 14.8 days (95% CI 13.9-15.7) for high volume, p=0.017 and for hospital size length of stay was equal to 16.8 days (95% CI 15.6-18.2) for low hospital size and 14.2 days (95% CI 13.0-15.2) for high hospital size, p<0.05.



There was a significant trend for 30 day mortality for oesophagectomy according to hospital volume quartile (quartile 1 to 4) (p=0.04) Annually 4 lives would be saved if regionalisation took place at HVHs for oesophagectomy (95% CI, 0-9)



There was approximately a 5% difference in 30 day mortality between LVHs and HVHs (15.55% and 10.88% respectively). After adjusting for patient and hospital characteristics, the odds ratio for oesophagectomy was 0.60 (95% CI=0.30 to 1.20)


Urbach (2005) (Cont.) Canada

Conventional modelling suggested an increased risk of 30-day mortality for the first quartile of surgeon volume (OR=2.55, 95% CI= 1.02-6.53) and third quartile (OR=3.01, 95% CI=1.33-6.81), compared with the highest surgeon-volume quartile. However, these would no longer be considered significant for the first quartile (OR=2.12, 95% CI=0.49-9.25) and third quartile (OR=2.93, 95% CI=0.70-12.28) of surgeon volume when using multilevel analysis. Width of CIs around estimates of volume categories on mortality estimated by multilevel models increased between 161.0% and 249%, compared with conventional models When conventional analysis was used, statistically significant associations between hospital volume and surgeon volume and length of stay were observed for most volume categories, however, wider CIs (when using multilevel analysis) resulted in estimates of effect that were no longer statistically significant

Combined results showing number of significant findings for all three procedures: Type of Modelling Technique: Conventional Multilevel Hospital Volume Surgeon Volume Hospital Volume Surgeon Volume 30 day mortality 0/9 2/9 0/9 0/9 Length of stay 7/9 8/9 0/9 1/9

The above table indicates the important differences in statistical significance between conventional methods and multilevel methods; however, the prognostic strength of this pooled data is not as persuasive as data concerned with oesophagectomy alone. 30-day mortality: sign. Association between volume and outcome was ID in 11% of comparisons using conventional compared with 0% of comparisons using multilevel analysis Length of stay: sign. Association between volume and outcome was ID in 83% of comparisons using conventional analysis compared with 6% of comparisons using multilevel analysis


Van Lanschot (2001) The Netherlands

There is a significant (inverse) relation between hospital volume and hospital mortality, decreasing from 12.1% in LVHs to 7.5% in MVHs and 4.9% in HVHs (p<0.001)

Appendix C 4.3: Financial Data – Oesophagectomy Authors Financial data


Unadjusted hospital charges for Low, Medium, and High Volume hospitals during each of the three time periods ($)

Time period Overall Low Volume Medium Volume High Volume P value 1984-1989 43,046

(30,000-66,000) 42,012 (29,000-74,000)

45,314 (30,000-63,000)

35,774 (27,000-61,000)

<0.001

1990-1994 33,531 (24,000-55,000)

46,721 (29,000-84,000)

37,297 (27,000-63,000)

25,801 (21,000-36,000)

<0.001

1995-1999 24,479 (18,000-39,000)

31,934 (24,000-59,000)

37,884 (27,000-55,000)

19,378 (17,000-24,000)

<0.001

Overall 1984-1999 33,483 (23,000-55,000)

42,318 (29,000-60,000)

39,979 (27,000-71,000)

23,072 (19,000-34,000)

<0.001

Results of multivariate analyses for charges

Independent Variable Adjusted % increase Hospital charges (95% CI) P value Medium volume -1% (-10-1) High volume -35 (-41 to -28) P<0.05 Age >65 0 (-1-1) Male -7 (-14-1) Non-White 19 (9-31) P<0.05 1990-1994 1 (-9-12) 1995-1999 -17 (-26 to -8) P<0.05 Urgent admission 15 (3-24) P<0.05 Emergent admission 16 (2-31) P<0.05 Malignancy 12 (3-24) P<0.05 Renal disease 44 (-25 to -175)

Median hospital charges for all patients were $33,483 ($22,722 to $55,186) High volume hospitals had significantly lower charges compared with low and medium volume hospitals during the 15 year study period (p<0.001). After adjusting for inflation there was a dramatic reduction in hospital charges regardless of volume during each time period (p<0.001)

Appendix C 4.3: Financial Data – Oesophagectomy (continued) Authors Financial data


Univariate analysis of independent factors associated with increased hospital charges

Independent variable P value Male 0.007 Increasing age 0.02 Non-white race <0.001 Urgent admission 0.001 Emergent admission <0.001 Extent of procedure 0.005 Malignancy 0.0004 Metastatic disease 0.009 History of myocardial infarction 0.01

In a multivariate analysis, adjusted for time period and casemix, high volume hospitals were independently associated with a decrease in hospital charges (35%; 95% CI 28-41; p<0.001) Using a median regression the decrease in charges at high volume hospitals was reported as equalling $11,673 (95% CI $9,504 to 12,841; p<0.001) A reduction of charges of 17% (95% CI, 7-26: p=0.001) was reported for the third time period (1995-1999) independent of hospital volume.

Authors Financial data


Average total charges Statewide Very Low Low Medium High Unadjusted 29,932 32,516* 32,852† 31,962* 25,727 Adjusted** NA 24,049* 23,818* 24,982* 21,393

* p<0.001, with high volume as comparator **Total hospital charges are adjusted for age, gender, race, admission status, payment source, place of residence, comorbidity score, time period, procedure and diagnosis † p<0.01 High volume hospital charges were $2,425 (14%) less than low volume hospital charges


Kuo (2001) The United States of America

The median statewide total charge was $46,871 (mean $67,592). High and low volume hospitals charged $48,764 (mean $72,060) and $42, 357 (mean 61,790), (p<0.001) respectively. After both covariate and cluster analysis none of these costs were significant, only a $755 (p=0.33) difference was reported. When patients died, there was a 1.8 times higher hospital charge at high volume hospitals ($103,296) compared with low volume ($57,057), (p<0.001).

Total cost Statewide Low High P value Median 25,101 24,763 25,518 0.33 IQR 19,392-37,392 16,975-38,107 20,392-37,091 Mean* 36,999 35,539 38,124 0.22

*Cluster analysis with multiple linear or logistic regression model adjusted for age, race, comorbidity score, urgency of admission, source of admission, year, payer type, and residence Charges in the above table are reported at 1999 rates

Authors Financial data

Patti (1998) The United States of America

Relationship of hospital volume to total hospital charges.

Number of operations over 5 years Total charges 1-5 $94,781 6-10 $87,887 11-20 $107,545 21-30 $100,788 >30 $118,500

There was a statistically significant increase in charge from the lowest to the highest volume hospitals (p<0.05.)


Swisher (2000) The United States of America

Hospital use and hospital charges

Actual hospital charges (95% CI) Actual hospital charges minus expected hospital charges* Cancer specialisation National Cancer Institutions 42,113 (39.097-45,356) 15,812 (11,872-19,751) Community Hospitals 67,535 (50,945-89,518) 40,629 (24,978-56,280) P value <0.005 <0.05 Oesophagectomy volume ≥5 cases/year 39,867 (36,839-43,144) 14,752 (10,679-18,825) <5 cases/year 62,094 (52,976-72,773) 29,679 (19,764-39,594) P value <0.005 <0.05 Total Operative Volume ≥3333 cases/year 40,380 (37,291-43,726) 14,334 (10,200-18,469) <3333 cases/year 58,413 (49,726-68,631) 30,524 (21,072-39,976) P value <0.005 <0.05 Hospital Size ≥600 beds 38,300 (34,341-42,715) 15,844 (10,688-21,006) <600 beds 50,833 (46,360-55,731) 20,315 (14,572-26,058) P value <0.05 NS

*Expected hospital charges were obtained by using expected outcomes developed from the 10 million- patient database of the national HCUP survey Hospitals with higher volumes showed a significant decrease in charges ($39,867 vs. $62,094, p<0.005) A multivariate analysis reported that the most significant risk factor for increased hospital costs were hospital volume (ß=1.42, P<0.003) and hospital size (ß=1.29 P<0.002)


STUDY DESIGN TABLES

Appendix C 5.1: Study design tables – Prostatectomy

Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Begg (2002) The United States of America

Hospital Volume and/or Surgeon Volume and/or Surgical Volume focus: Hospital and Surgeon Volume Population Number:

Low Medium High Very High Hospital Volume

(n =11,522)

2736 2940 2899 2947

Surgeon Volume

(n = 10,737)

2662 2837 2555 2683

Age:

Low Medium High Very High Hospital Volume (70) (70) (70) (70)

Surgeon Volume (70) (70) (70) (71)

Hospital Number:

Low Medium High Very High Hospital Volume (n=403) 280 67 37 19

Surgeon Number:

Low Medium High Very High Hospital Volume (n=999) 642 198 103 56

Volume Definitions: Hospital: pations/hospital

Low Medium High Very High Hospital Volume 1 - 33 34 - 61 62 - 107 108 – 252

Level of Evidence: III-3 Follow-up: 1 Yr: 337 patients 2nd Yr: 287 Lost to Follow-up: 1 Yr: 11,185 2nd Yr: 11,235 Study Period: 1992 - 1996 Outcome Measures: 30, 60 Day Mortality Post operative complications Late urinary complication Long-term incontinence Data Source: Surveillance, Epidemiology and End Results (SEERS) database (Medicare linked)

Condition: Prostate Cancer Procedure: Radical Prostatectomy ICD- 9 Classification: NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Clustering Casemix Age: Recorded not adjusted Race: Recorded not adjusted Comorbidities: Recorded not adjusted Romano Charlson Cancer Stage: NR

Inclusion criteria: NR Exclusion criteria: Not treated in a SEER state. Not enrolled in Medicare A or B

Appendix C 5.1: Study design tables – Prostatectomy (continued)

Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Begg (2002) (Cont.) The United States of America

Surgeon:

Low Medium High Very High Hospital Volume 1 - 10 11 - 19 20 - 32 33 – 121

End Points: Morbidity: See Table 66: Relation between Surgeon Volume and select outcomes in 10737 men Mortality: See Table67: Reported mortality rate per Hospital Volume and Surgeon Volume.

Table 64: Relation between Hospital Volume and select outcomes in 11522 men

Hospital Volume Low ( % of px) Medium ( % of px) High ( % of px) Very High ( % of px) Adjusted for clustering and value

Adjusted for clustering and casemix

Post operative complications 32 31 30 27 0.02 0.03 Late Urinary Complications Symptoms & Procedures 28 29 23 20 <0.001 <0.001 Major events 18 19 16 13 <0.001 <0.001 Long Term incontinence Symptoms & Procedures 19 19 18 18 0.38 0.21 Major events 6.5 6.4 7.0 7.6 0.22 0.34


Table 65: Relation between Surgeon Volume and select outcomes in 10737 men

Surgeon Volume Low Medium High Very High Adjusted for clustering and value


Post operative complications 32 31 30 26 0.008 <0.001 Late Urinary Complications Symptoms & Procedures 28 26 27 20 0.003 0.001 Major events 19 18 17 14 0.01 0.01 Long Term incontinence Symptoms & Procedures 20 20 19 16 0.08 0.04 Major events 7.3 7.2 6.7 6.6 0.82 0.34

Table 66: Reported mortality rate per Hospital Volume and Surgeon Volume.

Hospital Volume Low ( % of px) Medium High Very High Adjusted for clustering and value


30 Days 0.5 0.5 0.5 0.5 0.92 0.81 60 Days 0.6 0.6 0.6 0.5 0.94 0.68 Surgeon Volume 30 Days 0.4 0.5 0.5 0.5 0.71 0.74 60 Days 0.5 0.5 0.6 0.6 0.74 0.59


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Chun et al. (2006) Canada

Hospital Volume and/or Surgeon Volume: Surgeon volume Population Number: Pn = 2475 73 excluded Analysed Pn = 2402 Restricted dataset Pn = 1109 Patients treated by highest SV Pn = 1293 Age: NR Hospital Number: Hn = 1 (single institution) Surgeon Number: Sn = 11 Surgical volume (mean) {range} = 201 {1 – 1293} Volume Definitions: Hospital: NR Surgeon:

Surgeon Individual SV 1 & 2 1 3 27 4 65 5 97 6 140 7 146 8 182 9 213 10 237 11 1293

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: January 1996 – January 2004 Outcome Measures: Rate of positive surgical margins (PSM) after RP Data Source: Prospective clinical cases

Condition: Prostate cancer (biopsy confirmed and clinically localised) Procedure: Radical prostatectomy (RP) ICD-9 Classification: NR Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: See Table 68: Descriptive characteristics of RP patients Age: NR Race: NR Comorbidities: NR

Inclusion criteria: NR Exclusion criteria: Missing data on: pathological stage; post-operative Gleason sum; seminal vesicle invasion; surgical margin status; date or surgery; pre-treatment PSA


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Chun et al. (2006) (Cont.) Canada


All px (Pn = 2402)

Restrict. dataset

(Pn = 1109)

Highest SV (Pn = 1293)

p

Mean SV (median) {range}

201 (1293) {1 to 1293}

171 (182) {1 to 237}

1293 -

Mean PSM rt (median) {range}

20.2 (21.4) {0 to 32.9}

22.6 (25.9) {0 to 32.9}

18.9 <0.001

Individual SV (%) with corresponding SV rates (%)

Surgeon Individual SV (%) PSM rates, % 1 & 2 0 0 3 27 (1.1) 25.9 4 65 (2.7) 20.0 5 97 (4.0) 22.7 6 140 (5.8) 21.4 7 146 (6.1) 32.9 8 182 (7.6) 29.1 9 213 (8.9) 30.0 10 237 (9.9) 21.1 11 1293 (53.8) 18.9

Mortality: NR Length of stay: NR


Table 67: Descriptive characteristics of RP patients

All patients Restricted dataset Highest SV p* Number of men 2402 1109 1293 Mean PSA level ng/mL (median) {range}

0.08

9.4 (7.0) {0.4 - 125.0} 9.7 (7.1) {0.6 - 125.0} 9.1 (6.8) {0.4 - 82.6} Clinical stage, n (%) <0.001 T1c 1596 (66.7) 704 (63.4) 904 (69.9) T2a 685 (28.7) 330 (29.7) 353 (27.3) T2b 80 (3.3) 51 (4.6) 30 (2.3) T3 32 (1.3) 26 (2.3) 6 (0.5) Biopsy Gleason sum 0.7 2 – 5 265 (11.0) 126 (11.4) 136 (10.5) 6 1412 (58.8) 650 (58.6) 766 (59.2) 7 – 10 725 (30.2) 333 (30.0) 391 (30.2) Pathological Gleason sum 0.4 2 – 5 300 (12.5) 129 (11.6) 171 (13.2) 6 841 (35.0) 400 (36.1) 441 (34.1) 7 – 10 1261 (52.5) 580 (52.3) 681 (52.7) Extracapsular extension 733 (30.5) 350 (31.6) 383 (29.6) 0.3 Seminal vesicle invasion 265 (11.0) 132 (11.9) 133 (10.3) 0.2 Lymph node invasion 72 (3.0) 28 (2.5) 44 (3.4) 0.2 *patients of the surgeon with the highest SV compared to those of the remaining surgeons


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Ellison (2000) The United States of America


Low Medium High 22167 22187 22339

Age:







Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 01/01/1989 – 31/12/1995 Outcome Measures: In-hospital mortality Length of stay Total Hospital charges Data Source: Nationwide Inpatient Sample 11 hospitals during 1989 – 1992 17 hospitals during 1993 – 1994 19 hospitals in 1995

Condition: Prostate cancer Procedure: Radical prostatectomy ICD- 9 Classification: 60.5 Training Hospital: % Training hospitals Low: 30.6 Medium: 54.9 High: 60.0 Institutional/Environmental Support: NR Selective Referral: Covariates: Adjusted for in OR Age: Race: Comorbidities: (ICD-9) Myocardial infarction (412) Peripheral vascular disease (440.0 to 443.9) Chronic pulmonary disease (415.0, 416.8 to 416.9, 491 to 494) Dementia (290.0 to 290.9 and 331.0 to 331.2) Diabetes (290.0 to 290.9 and 331.0 to 331.2)



Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Ellison (2000) (Cont.) The United States of America

Mortality:

Low Medium High Percentage observed mortality

0.30 0.28 0.17

OR (95% CI) 1.75 (1.2 – 2.6) 1.67 (1.1 – 2.5) 1.0 Adjusted OR (95% CI)

1.78 (1.2 – 2.7) 2.71 (1.2 -2.6) 1.0

Mean length of stay: 1995 (Yr)

Low Medium High Mean 5.4 (5) 4.8 (4) 4.2 (4)

Total Hospital Charges: 1995 (Yr)

Low Medium High Charges $15,600 $15,100 $13,500

Comorbidities: (ICD-9) Diabetes with complication (250.4 to 250.99) Mild liver disease (571.2, 571.5, 571.6, 571.8 and 571.9) Severe liver disease (572 TO 572.4 and 456.0 to 456.29) Chronic renal failure (585.0 to 586.9, V 451 and V56.0 to V56.9) V420 Various cancers (140.0, to 171.9, 174 to 195.9, to 200.0 to 208.8, 273 to 273.3 and V104.6) and Metastatic solid tumour (196.0 to 199.9) Mean comorbidity score




Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = Total 66693 Number of patients in each volume defined hospital

Low Medium High # Patients 22167 22187 22339

Age:

Low Medium High Mean 65.5 65.2 65


Low Medium High Hospital 1012 222 100

Surgeon Number: Sn =NA Volume Definitions: Hospital: Low: <25 Medium: 25 - 54 High: >54 Surgeon: NA End Points: Morbidity: NR

Level of Evidence: II III-3 Follow-up: NR Lost to Follow-up: NR Study Period: 01/01/1989 – 31/12/1995 Outcome Measures: Mortality Rates Length of stay Total hospital charges Data Source: Nation Wide Inpatient Sample. (This stratified probability sample was taken from: 11 hospitals 1989 – 1992 17 hospitals 1993 – 1994 19 hospitals 1995

Condition: Prostate Cancer Procedure: Radical Prostatectomy ICD- 9 Classification: 60.5 Training Hospital:

% Teaching Hospital


Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: NR Race: NR




Mortality:

Low Medium High OR (95% CI) 0.30 0.28 0.17 OR (95% CI) Adjusted

1.75 (1.2 – 2.6) 1.67 (1.1 – 2.5) 1.0

Length of stay:} 1995 (Yr)

Low Medium High Mean 5.4 4.8 4.2

Total Hospital Charges: 1995 (Yr)

Low Medium High Charges $15,600 $15,100 $13,500

Comorbidities:

Comorbidity Score (Mean)


Cancer Stage NR



Hospital Volume and/or Surgeon Volume: Hospital volume Population Number: Pn = 12635 Number of patients treated in each volume-defined hospital:

Low Medium High Very high # patients (%) 1953 (15.46) 2794 (22.11) 3098 (24.52) 4790 (37.91)

Age, years (mean):

Low Medium High Very high Mean age 69.3 69.5 69.8 70.2

p = 0.004 Hospital Number: Hn = 348 Number of hospitals in each volume category:

Low Medium High Very high # hospital (%) 222 (63.80) 60 (17.23) 38 (10.92) 28 (8.04)

Surgeon Number: Sn = N/A Volume Definitions: Based on the number of radical prostatectomies performed at an institution between 1991 and 1994 Hospital: Low: 1 to 33 Medium: 34 to 61 High: 62 to 107 Very high: 108 - 303 Surgeon: NA

Level of Evidence: III-3 Follow-up: Variable – until failure of cancer control, death or censored on December 31, 1999. Lost to Follow-up: NR Study Period: 1990 – 1999 Medicare files from 1990 – 1994 Outcome Measures: Failure of cancer control (defined as the use of hormone ablative therapy (medical or surgical) or radiation therapy more than 6 months after RP) Data Source: SEER-Medicare linked files. Surveillance, Epidemiology and End-Results (SEER) cancer registry captures disease specific measures and treatment data on all incident cases within 5 states and 6 metropolitan areas of the United States. Medicare program provides healthcare coverage to individuals aged 65 years or older.

Condition: Prostate cancer Procedure: Radical prostatectomy (RP) ICD- 9 Classification: 60.5 CPT codes for hormone & radiation therapy: 54520, 77261, 77499 Health Care Finance Administration Current Procedural Coding System codes for hormone therapy: Lupron™ J1950, J9217, J9218 Goserelin J9202 Diethylstilbestrol J9156 Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: NR Race: NR

Inclusion criteria: Patients undergoing radical prostatectomy as as an initial form of treatment for newly diagnosed (incident) prostate cancer Exclusion criteria: Patients coded within SEER dataset as having undergone combined treatment with surgery and radiation therapy



End Points: Morbidity: NR Mortality: All cause mortality (%):

Low Medium High Very high Mortality (%) 15.7 15.7 15.1 15.8

p = 0.85 Prostate cancer mortality

Low Medium High Very high Mortality (%) 2.7 2.8 2.8 2.8

p = 0.99 10 year overall mortality or 10 year prostate cancer specific mortality did not vary by hospital volume Length of stay: NR

Comorbidities: Assessed using Charlson score LVH: 2.9 MVH: 2.9 HVH: 2.9 VHVH: 2.9 p = 0.73 See below for baseline cancer Grades and Stages for each defined hospital volume.


Table 68: Patient characteristics:

LVH MVH HVH VHVH p Grade (%) Well 14.2 10.2 10.6 7.1 NR Moderate 61.7 68.1 67.0 67.7 NR Poor 21.5 20.4 20.7 23.7 NR Undifferentiated 0.4 0.5 0.5 0.4 NR Unknown 2.1 0.8 1.2 1.1 <0.001 Stage (%) Local 49.3 45.2 44.2 46.8 NR Regional 35.3 39.3 37.8 41.8 NR Distant 0.6 0.4 0.3 0.2 NR Unknown 14.8 15.1 17.7 11.2 0.37 Crude adjuvant therapy rate 36.9 33.4 32.8 34.7 0.01

Table 69: Hazard ratios for the use of adjuvant therapy after radical prostatectomy stratified by hospital volume

Model 1 Model 2 Model 3 Hazard ratio 95% CI p value Hazard ratio 95% CI p value Hazard ratio 95% CI p value

Hospital volume LVH 1.17 1.06 to 1.28 0.002 1.24 1.13 - 1.37 <0.001 1.25 1.14 - 1.38 <0.001 MVH 1.05 0.96 to 1.15 0.244 1.09 0.99 - 1.19 0.054 1.11 1.01 – 1.21 0.023 HVH 1.00 0.92 to 1.09 0.928 1.02 0.94 - 1.12 0.589 1.03 0.94 - 1.12 0.570 VHVH - - - Grade Well - - Moderate 1.38 1.20 - 1.58 <0.001 1.37 1.19 - 1.58 <0.001 Poor 2.42 2.09 - 2.81 <0.001 2.25 1.94 - 2.60 <0.001 Undifferentiated 3.97 2.72 - 5.79 <0.001 3.12 2.13 - 4.57 <0.001 Stage Local - - Regional 1.63 1.53 - 1.75 <0.001 1.51 1.40 - 1.62 <0.001 Distant 4.01 2.76 - 5.85 <0.001 3.24 2.23 - 4.73 <0.001 Age 1.00 0.99 - 1.01 0.497 Charlson score 1.07 1.06 - 1.08 <0.001


Authors Procedure Study Design Study Variables Inclusion/Exclusion Criteria Hollenbeck (2007) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital Volume Population Number: Pn = 141 052 Age: Mean (95% CI) 62.7 (62.6-62.7) Hospital Number: Hn = Surgeon Number: Sn = NA Volume Definitions: Hospital: Average number of procedures performed per volume category over study period.

Low High Mean 5.0 297.6 SD 3.2 209.6

Surgeon: NA End Points: Morbidity: NR Mortality: Operative Mortality %

Low High Prostatectomy 0.3 0.04

Odds Ratio for Operative Mortality (Bottom vs. Top Decile)

Unadjusted OR


Prostatectomy 6.2 2.8-13.3 3.8 1.8-7.9

Level of Evidence: III-3 Follow-up: U Lost to Follow-up: NR Study Period: 1993-2003 Outcome Measures: Intraoperative death (Intraoperative surgical death, death during course of hospitalization) Prolonged length of stay (Patients whose length of stay was greater than the 90th percentile) Data Source: Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample (NIS)

Condition: Prostate Cancer Procedure: Suprapublic Prostatectomy Retropubic Prostatectomy Radical Prostatectomy Other Prostatectomy Excision of Lesion, Prostate Perineal Prostatectomy Other Prostatectomy ICD- 9 Classification: Prostatectomy

Suprapublic 60.3 Retropubic 60.4 Radical 60.5 Other 60.6 Excision of 60.61 Perineal 60.62 Other 60.69

Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: Mean (95% CI) 62.7 (62.6-62.7)


Appendix C.1 Study design tables – Prostatectomy (continued)

Authors Procedure Study Design Study Variables Inclusion/Exclusion Criteria Hollenbeck (2007) (Cont.) The United States of America

Mortality: C Statistic



Prostatectomy 0.74 0.74 Length of stay: Prolonged Length of Stay

Low High Prostatectomy 19.0 3.9


Unadjusted OR


Prostatectomy 5.7 4.0-8.2 4.8 3.5-6.7 C Statistic



Prostatectomy 0.65 0.70

Race: %

White 63.9 African American 8.0 Hispanic 3.2 Other 2.5 Missing 22.4

Sex: Women % 0 Comorbidities: NR Other: Admission type: % Urgent/ Emergent admission = 14.7 Insurance: % Medicare = 38.2 Private = 57.0 Other = 4.8

Table 70: Operative Mortality


Adjusted attributable risk Lives saved Lives saved per 100 000 US population (male)

% 95% CI No. 95% CI

Prostatectomy

6 462 73.5 44.6-87.4 142 86-469

0.11

Appendix C.1 Study design tables – Prostatectomy (continued)



Adjusted risk factor Earlier Discharges Earlier discharges per 100,000 US population

% 95% CI No. 95% CI

Prostatectomy

6 462 75.8 68.3-81.2 10 209 9 202-10 939

7.67


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Hu (2003) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital volume and surgeon volume Population Number: Pn for hospital data = 2292, Pn for surgeon data = 2072 1953 (85.2%) RP performed in low volume hospitals 339 (14.8%) RP performed in high volume hospitals 1911 (92.2%) RP performed by low volume surgeons 161 (7.8%) RP performed by high volume surgeons Age (years): number (%)

Hospital volume Surgeon volume Low High Low High

65-69 1045 (53.5) 206 (60.8) 1038 (54.3) 88 (54.7) 70-74 676 (34.6) 114 (33.6) 666 (34.9) 59 (36.7) ≥75 232 (11.9) 19 (5.6) 207 (10.8) 14 (8.7)

Hospital Number: Hn = 1210 Low volume = 1166 High volume = 44 Surgeon Number: Sn = 1788 Low volume = 1749 High volume = 39 Volume Definitions: Based on cumulative experience in 1997/1998 Hospital: Low: <60 RP/year, High: ≥60 RP/year Surgeon: Low: <40 RP/year, High: ≥40 RP/year

Level of Evidence: III-3 Follow-up: 12 months Lost to Follow-up: NR Study Period: 1997-1998 Outcome Measures: In-hospital mortality Complications Hospital length of stay Anastomotic strictures Data Source: 5% national random sample of 1997-1998 claims data from the Center for Medicare and Medicaid Services (USA)

Condition: Prostate cancer Procedure: Radical prostatectomy (RP) ICD-9 Classification: 60.5 Physicians Current Procedural Terminology Coding System (CPT-4) code: 55810, 55812, 55815, 55840, 55842, 55848 Training Hospital: High-volume hospitals were more often academically affiliated (p<0.001) Institutional/Environmental Support: NR Selective Referral: NR Covariates: All=OR (95% CI) except LOS=PE (95% CI) Age: 70-74 vs 65-69 In-hosp comps = 1.15 (0.91 - 1.46) Anas. stricture = 1.03 (0.80 - 1.32) Mean LOS = 0.21 (-0.11 - 0.53) >74 vs 65-69 In-hosp comps = 1.94 (1.39 - 2.70) p<0.05 Anas. stricture = 2.21 (1.54 - 3.15) p<0.05 Mean LOS = 2.26 (1.75 - 2.77) p<0.05

Inclusion criteria: NR Exclusion criteria: 220 had missing physician information and were excluded from surgeon and multivariate analysis


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Hu (2003) (Cont.) The United States of America

End Points: Morbidity: Complications By hospital volume:

Low volume High volume p Number (%) 421 (21.6) 57 (16.8) 0.05

High hospital volume OR (95% CI) of complications = 0.84 (0.59 - 1.19) By surgeon volume:

Low volume High volume p Number (%) 419 (21.9) 19 (11.8) <0.01

High surgeon volume OR (95%CI) of complications = 0.53 (0.32 - 0.89) p<0.05 Anastomotic stricture By hospital volume:


High hospital volume OR (95% CI) of anastomotic stricture = 0.72 (0.49 - 1.04) By surgeon volume:


High surgeon volume OR (95% CI) of anastomotic stricture = 0.89 (0.55 - 1.44) Mortality: NR Length of stay: LOS by hospital volume:

Low volume High volume p Days, mean ± SD 5.2 ± 3.8 4.4 ± 2.1 <0.01

Race: Nonwhite In-hosp comps = 1.09 (0.80 - 1.49) Anas. stricture = 1.00 (0.71 - 1.40) Mean LOS = 0.60 (0.15 - 1.05) p<0.05 Comorbidities: Assessed using Charlson index score – higher score indicates greater co-morbidity Charlson 1 or 2 vs 0 In-hosp comps = 1.22 (0.98 - 1.53) Anas. stricture = 0.85 (0.67 - 1.08) Mean LOS = -0.33 (-0.55 - -0.03) p<0.05 Charlson 3 or greater vs 0 In-hosp comps = 1.10 (0.72 - 1.69) Anas. stricture = 0.66 (0.42 - 1.05) Mean LOS = 0.33 (-0.26 - 0.92) Geographic location: South vs Northeast In-hosp comps = 1.05 (0.76 - 1.46) Anas. stricture = 1.18 (0.82 - 1.70). Mean LOS = -0.93 (-1.36 - -0.50) p<0.05 West vs Northeast In-hosp comps = 0.58 (0.38 - 0.88) p<0.05 Anas. stricture = 1.04 (0.68 - 1.58) Mean LOS = -1.63 (-2.19 - -1.07) p<0.05 Midwest vs Northeast In-hosp complications = 0.86 (0.62 - 1.20) Anas. stricture = 0.94 (0.65 - 1.35) Mean LOS = -1.19 (-1.66 - -0.72) p<0.05 Mutlivariate regression analysis model fit: In-hosp comps: C=0.59 Anas. stricture: C=0.60 Mean LOS: R2=0.08


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Hu et al. (2003) (Cont.)

Mean length of stay, parameter estimate (95% CI) High hospital volume PE = -0.42 (-0.89 - 0.05) LOS by surgeon volume:

Low volume High volume p Days, mean ± SD 5.2 ± 3.7 4.1 ± 2.6 <0.01

Mean length of stay, parameter estimate (95% CI) High surgeon volume BE= -0.66 (-1.26 to -0.06) p<0.05

Academic Affiliation vs. non Academic affiliation In Hospital 1.05 (0.80 – 1.37) Anastomotic Stricture 1.10 (0.83-1.46) M.L.O.S -0.03 (-0.39 – 0.34) Academic Affiliation vs Non-Academic Affiliation: In-hosp comps: 1.05 (0.80 – 1.37) Anas. stricture: 1.10 (0.83 – 1.46) Mean LOS: -0.03 (-0.39 – 0.34)

Table 72: Outcomes stratified by hospital and surgeon volume:

p Low hospital, low surgeon

High hospital, low surgeon

Low hospital, high surgeon

High hospital, high surgeon

Hospital Main effect

Surgeon Main effect

Interaction Effect

In hospital complications

378 (22.4) 41 (18.6) 9 (13.6) 10 (10.5) 0.21 0.10 0.90

Anastomotic stricture 362 (28.4) 39 (22.7) 13 (29.6) 14 (17.7) 0.12 0.87 0.45 Length of stay 5.2 ± 3.8 4.7 ± 3.5 4.8 ± 3.7 3.7 ± 1.1 <0.001 <0.001 <0.001


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Konety (2006) The United States of America

Hospital Volume and/or Surgeon Volume: Hospital volume Population Number: Pn = 61,039 Age: NR Hospital Number: Hn = 1,552 Surgeon Number: Sn = NR Volume Definitions: Utilised the Leapfrog group thresholds for CABG, PCI, AAA, PAN & ESO to categorise hospitals. Hospitals that met one or more Leapfrog volume standards were compared to those that did not. Hospital:

Low Medium High ≤6 >6 - ≤20 >20

Surgeon: NR End Points: Morbidity: NR Mortality: 0.11% (66 deaths) Length of stay: NR

Level of Evidence: III-3 Follow-up: NR Lost to Follow-up: NA Study Period: 1998 - 2002 Outcome Measures: Post-operative mortality Data Source: National Inpatient Sample (NIS) of the Healthcare Utilization Project

Condition: Prostate cancer (PC) Procedure: Radical prostatectomy (RP) ICD- Xx Classification: ICD-9-CM Training Hospital: NR Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: NR Race: NR Comorbidities: NR



Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Yao (1999) USA

Hospital Volume and/or Surgeon Volume: Hospital volume Population Number: Pn = 101,604 Age (median): (69) Hospital Number: Hn = 2849 Low volume: 2013 Medium-low volume: 463 Medium-high volume: 257 High volume: 116 Surgeon Number: (Mean), [SD], {Range} Sn = NA 86.7% of surgeons performing RP were urologists Volume Definitions: Classifications based on the number of prostatectomies performed on eligible patients during 1991 – 1994 Hospital: Low volume: ≤25th percentile or ≤ 38 RP in study period Medium-low volume: 26th – 50th percentile or 39 – 74 RP in study period Medium-high volume: 51st – 75th percentile or 75 – 140 RP in study period High volume: ≥76th percentile or ≥141 RP in study period Surgeon: NA

Level of Evidence: III-3 Follow-up: At least 30 days Lost to Follow-up: NR Study Period: 1991 – 1994 Year of surgery: 1991: 22.5% 1992: 31.1% 1993: 25.2% 1994: 21.2% Outcome Measures: Length of stay Surgical complications Readmission rate Mortality rate in 30 days post-surgery Data Source: Medicare claim records

Condition: Prostate cancer Procedure: Radical prostatectomy ICD- 9 Classification: 60.5 Physicians Current Procedural Terminology Coding System codes: 55810, 55812, 55815, 55840, 55842, 55845 Training Hospital: 15.5% teaching hospitals(hospitals with accredited graduate training programs in urology) Institutional/Environmental Support: NR Selective Referral: NR Covariates: Age: NR Race: Baseline Caucasian: 89.5% African-American: 5.1% Other: 5.4%

Inclusion criteria: Medicare beneficiaries, aged 65 years or older Exclusion criteria: Men enrolled in health maintenance organisations or treated at Department of Veterans Affairs hospitals


Authors Procedure Study Design Procedure Inclusion/Exclusion Criteria Yao (1999) (Cont.) USA

End Points:

Mean rates (95% confidence interval) Volume Overall complications*

30-day readmission†

30-day mortality rates‡

Low 31.3% (30.8-31.9%) 5.0% (4.7-5.3%) 0.63% (0.53-0.73%) Medium-low 28.7% (28.2-29.3%) 4.5% (4.3-4.8%) 0.59% (0.49-0.68%) Medium-high 27.8% (27.2-28.3%) 4.3% (4.0-4.5%) 0.56% (0.47-0.66%) High 26.3% (25.8-26.9%) 4.1% (3.8-4.3%) 0.39% (0.31-0.46%)

* p for trend = 0.2; † p for trend = 0.3 ‡ p for trend = 0.0015

Outcome indicator, relative risk (95% confidence interval) 30 day

mortality Serious complications

Any complications

Readmission in 30 days

Low vs. high 1.51* (1.25 to 1.77)

1.43* (1.37 to 1.48)

1.28* (1.24 to 1.32)

1.30* (1.21 to 1.39)

M-L vs. high 1.43* (1.17 to 1.69)

1.25* (1.19 to 1.31)

1.13* (1.08 to 1.17)

1.16* (1.07 to 1.25)

M-H vs. high 1.42* (1.16 to 1.68)

1.09* (1.03 to 1.15)

1.08* (1.04 to 1.12)

1.08† (0.99 to 1.17)

† p = 0.10; *p ≤ 0.009 Length of stay

Hospital volume Mean LOS (days) 95% confidence interval Low 8.51 8.47 to 8.56 Medium-low 8.18 8.14 to 8.22 Medium-high 7.70 7.66 to 7.74 High 7.81 7.77 to 7.85

p for trend = 0.0001 In within-hospital longitudinal comparisons, the length of stay of the patient in hospital decreased throughout the study period. Hospitals that experienced a relative increase in study volume during the study period demonstrated larger volume-related decreases in LOS when compared with that for hospitals that experienced a relative decrease in volume during the study period (see table below)

Comorbidities: Baseline, % patients affected Hypertension: 26.3% Cardiac: 24.0% Pulmonary: 15.0% Diabetes: 7.2% Renal disease: 4.5% Any comorbidity: 54.9% Comorbidities were included as covariates in the multivariate analyses, this inclusion did not alter the results. Other: Surgeon Speciality Hospital Teaching Status Year of diagnosis


Table 73: Changes in length of hospital stay (days) according to changes in hospital surgical volume and quartile of hospital volume

Hospital volume from 1991 through 1994 Change in hospital surgical volume over time Relatively increased volume Relatively unchanged volume Relatively decreased volume Low 1.62 (1.33 to 1.91) 1.34 (1.12 to 1.57) 0.90 (0.63 to 1.17) Medium-low 1.42 (1.18 to 1.67) 1.38 (1.21 to 1.55) 1.07 (0.89 to 1.24) Medium-high 1.50 (1.29 to 1.72) 1.29 (1.12 to 1.47) 1.19 (1.02 to 1.36) High 1.49 (1.27 to 1.70) 1.37 (1.17 to 1.57) 1.24 (0.93 to 1.55) All 1.55 (1.37 to 1.73) 1.35 (1.18 to 1.51) 0.99 (0.83 to 1.16) P for trend = 0.0046 (Krukel-Wallis non-parametric test for trend)

Appendix C 5.2: Volume outcome tables – Prostatectomy (continued) Authors Volume outcome data

Begg (2002)

Hospital-related outcomes No relation between hospital volume and mortality (p = 0.81 @ 30 days; P = 0.68 @ 60 days) Post-operative complications lower in VHVH than LVH (27% vs. 32%, P = 0.03) Late urinary complications lower in VHVH than LVH (symptoms or procedures 20% vs. 28%, p < 0.001; major events 13% vs. 18%, P < 0.001) No relation between hospital volume and long-term incontinence (symptoms or procedures, p = 0.21; major events, P = 0.34) Surgeon-related outcomes No relation between surgeon volume and mortality (p = 0.74 @ 30 days; P = 0.59 @ 60 days) Post-operative complications lower when performed by VHVS than LVS (26% vs. 32%, P < 0.001) Late urinary complications lower when performed by VHVS than LVS (Symptoms or procedures 20% vs. 28%, P = 0.001; major events 14% vs. 19%, P = 0.01) Long term incontinence (symptoms or procedures) lower when performed by VHVS than LVS (16% vs. 20%, P = 0.04) No relation between surgeon volume and long term incontinence (major events) (P = 0.34) VHVS have lower rates of post-operative complications (26% vs. 30%, P < 0.001), late urinary complications (P < 0.001), and long term incontinence (P < 0.001) than HVS


Chun (2006)

Surgeon-related outcomes When patients of the highest volume surgeon were considered, surgeon volume was a statistically significant predictor of PSM (P < 0.001 for all models) before and after RP in both univariate and multivariate

analyses, and added significantly to PSM predictive accuracy (+1.5%, P < 0.001) Without patients of the highest volume surgeon, the univariate (before RP P = 0.6; after RP P = 0.7) and multivariate (before RP P = 1.0; after RP P = 0.6) effects of surgeon volume on predicting PSM were lost. Also,

surgeon volume had a negative effect on PSM predictive accuracy (before RP: -0.1%; after RP: -0.4%)


Ellison (2000)

Hospital-related outcomes Patients at LVH and MVH approximately 75% more likely to have in-hospital mortality than those in HVH (0.30%, 0.28%, and 0.17% respectively, P < 0.001) Patients ≥ 65y.o. at LVH or MVH approximately 60% more likely to have in-hospital mortality than those in HVH (0.40%, 0.38%, and 0.25% respectively, P < 0.001) 22% of patients at LVH had hospital stays of > 7 days, compared with 6% at HVH (P < 0.001) Hospital charges at LVH and MVH were greater than at HVH ($15 600, $15 100, and $13 500 respectively, P < 0.001)


Ellison (2005)

Hospital-related outcomes No relation between hospital volume and mortality (10-year overall or 10-year prostate cancer specific) Crude risk analysis: Patients at LVH 17% increased risk of receiving adjuvant therapy compared to VHVH (HR: 1.17, 95%CI: 1.07-1.27, P = 0.001) Controlling for histological grade, pathological stage, age & Charlson score: LVH 25% increased risk (HR: 1.25, 95%CI: 1.14-1.38, P < 0.001) and MVH 10% increased risk (HR: 1.11, 95%CI: 1.01-1.21, P = 0.023) of

receiving adjuvant therapy compared to VHVH Hospital volume had a small effect on use of adjuvant therapy for patients with low-grade disease, however LVH patients with more advanced grade disease had higher rates of adjuvant therapy (P < 0.001) LVH patients had higher rates of adjuvant therapy for each level of clinical stage (P < 0.001)

Authors Volume Outcome Relationship Hollenbeck (2007) The United States of America

Difference in operative mortality between low and high volume hospitals (3.8; 95%CI, 1.9-7.9) 19% of patients at a low volume hospital compared to 3.9% of patients at a high volume hospital had a prolonged length of stay. Adjusted mortality 3.8 (95% CI, 1.8-7.9) between lowest and highest volume decile. Unadjusted mortality 6.2 (95% CI, 2.8-13.3) between lowest and highest volume decile. Adjusted prolonged length of stay 4.8 (95% CI, 3.5-6.7) between lowest and highest volume decile. Unadjusted prolonged length of stay 5.7 (95% CI, 1.1-2.0) between lowest and highest volume decile.


Hu (2003)

Surgeon-related outcomes LVS had twice in-hospital complication rate of HVS (21.9% vs. 11.8%, p< 0.01) LVS patients had 1 day longer hospital stay than HVS patients (5.2 vs. 4.1 days, p< 0.01) Controlling for hospital volume and patient characteristics: HVS patients were half as likely to experience in-hospital complications (OR: 0.53, 95%CI: 0.32-0.89, p< 0.05) and more likely to have shorter hospital stays

(PE: -0.66, 95%CI: -1.26 to -0.06, p< 0.05) than LVS patients Hospital-related outcomes HVH experienced fewer anastomotic strictures than LVH (19.8% vs. 26.8%, p= 0.01) HVH experienced fewer complications than LVH (21.6% vs. 16.8%, p<0.05) HVH experienced shorter hospital stays (4.4 vs. 5.2 days, P < 0.01) Greater difference in length of patient hospital stay between LVS and HVS in HVH (4.7 vs. 3.7 days) than in LVH (5.2 vs. 4.8 days); interaction effect P < 0.001 When multivariate analysis is controlled for the interaction between surgeon and hospital volume becomes insignificant.


Konety (2006)

Hospital-related outcomes HVH and MVH patients have 78% (OR: 0.22, 95%CI: 0.11-0.45, p < 0.05 ) and 73% (OR: 0.27, 95%CI: 0.12-0.63, p < 0.05) lower odds of mortality, respectively, compared to LVH Controlling for Specialised Urology Centre Status and Meeting Leapfrog Volume Thresholds: HVH and MVH associated with lower odds of mortality (P < 0.05) in analyses of all Leapfrog cancer-related procedures No significant trends in hospital volume and odds of mortality


Yao (1999)

Hospital-related outcomes LVH, MLVH, and MHVH have a 30% (95%CI: 21%-39%), 16% (95%CI: 7%-25%), and 8% (95%CI: -1%-17%) greater risk of readmission, respectively, when compared to HVH LVH, MLVH, and MHVH have a 43% (95% CI: 37%-48%), 25% (95% CI: 19%-31%), and 9% (95% CI: 3%-15%) greater risk of serious complication, respectively, when compared to HVH LVH, MLVH, and MHVH have a 51% (95%CI: 25%-77%), 43% (95%CI: 17%-69%), and 42% (95%CI: 16%-68%) greater risk of mortality, respectively, when compared to HVH With exception of MHVH readmission rates, LVH, MLVH, and MHVH outcomes (mortality, serious complications, any complications, readmission) were inferior to those of HVH (p ≤ 0.009 for all comparisons; p ≤ 0.03

for trend) Mean length of stay in LVH 9% longer than HVH (8.51 vs. 7.81 days; p = 0.0001 for trend), while significant differences were found between all hospital volumes (p < 0.0001 for all comparisons) Longitudinal analyses: No relation between changes in hospital volume and changes in: surgical complications (p = 0.41); rate of readmission (p = 0.80); or mortality rate (p = 0.54) Hospitals that experienced a relative volume increase demonstrated 57% greater volume-related reduction in length of stay when compared to hospitals that experienced a relative volume decrease (p = 0.005; p =

0.0046 for trends), most evident in LVH Changes in hospital volume were highly associated with changes in length of hospital stay (p < 0.001 for trend) Initial hospital volumes not associated with changes in length of hospital stay (p = 0.99)

Appendix C 2.3: Financial Data – Prostatectomy Authors Financial data

Ellison (2000) The United States of America

Low Medium High P value Total Hospital Charges $15,600 $15,100 13,500 P <0.001

APPENDIX D – SEARCH STRATEGIES

Search Strategy

Abdominal Aortic Aneurysm CINAHL

1) Abdominal Aortic Aneurysm and Centrali?ation

2) Abdominal Aortic Aneurysm and Regionali?ation

3) Abdominal Aortic Aneurysm and Surgical Volume

4) Abdominal Aortic Aneurysm and Hospital Volume

5) Abdominal Aortic Aneurysm and Surgeon Volume

The Cochrane Collaboration






Current Contents Connect

1) Abdominal Aortic Aneursym

2) 1 and Centrali*

3) 1 and Regionali*

4) 1 and Surgical Volume

5) 1 and Hospital Volume

6) 1 and Surgeon Volume

Embase / Medline

1) * Abdominal Aortic Aneurysm

2) exp [Abdominal Aortic Aneurysm]

3) Abdominal Aortic Aneursym

4) Centrali$

5) Regionali$

6) Surgical Volume

7) Hospital Volume

8) Surgeon Volume

9) exp. Treatment Outcome

10) exp. Mortality

11) 1 or 2 or 3

12) 11 and 4 and 9

13) 11 and 5 and 9

14) 11 and 6 and 9

15) 11 and 7 and 9

16) 11 and 8 and 9

17) 11 and 4 and 10

18) 11 and 5 and 10

19) 11 and 6 and 10

20) 11 and 7 and 10

21) 11 and 8 and 10

The NHS CRD






Knee Arthroplasty CINAHL

1) Knee Arthroplasty and Centrali?ation

2) Knee Arthroplasty and Regionali?ation

3) Knee Arthroplasty and Surgical Volume

4) Knee Arthroplasty and Hospital Volume

5) Knee Arthroplasty and Surgeon Volume





4) Knee Arthroplasty and Hospital Volume



1) Knee Arthroplasty

2) 1 and Centrali*

3) 1 and Regionali*




Embase / Medline

1) * Knee Arthroplasty

2) exp [Knee Arthroplasty]

3) Knee Arthroplasty

4) Centrali$

5) Regionali$

6) Surgical Volume

7) Hospital Volume

8) Surgeon Volume


10) exp. Mortality

11) 1 or 2 or 3

12) 11 and 4 and 9

13) 11 and 5 and 9

14) 11 and 6 and 9

15) 11 and 7 and 9

16) 11 and 8 and 9

17) 11 and 4 and 10

18) 11 and 5 and 10

19) 11 and 6 and 10

20) 11 and 7 and 10

21) 11 and 8 and 10

The NHS CRD




4) Knee Arthroplasty m and Hospital Volume


Liver Resection CINAHL

1) Liver Resection and Centrali?ation

2) Liver Resection and Regionali?ation

3) Liver Resection and Surgical Volume

4) Liver Resection and Hospital Volume

5) Liver Resection and Surgeon Volume








1) Liver Resection

2) 1 and Centrali*

3) 1 and Regionali*




Embase / Medline

1) * Liver Resection

2) exp [Liver Resection]

3) Liver Resection

4) Centrali$

5) Regionali$

6) Surgical Volume

7) Hospital Volume

8) Surgeon Volume


10) exp. Mortality

11) 1 or 2 or 3

12) 11 and 4 and 9

13) 11 and 5 and 9

14) 11 and 6 and 9

15) 11 and 7 and 9

16) 11 and 8 and 9

17) 11 and 4 and 10

18) 11 and 5 and 10

19) 11 and 6 and 10

20) 11 and 7 and 10

21) 11 and 8 and 10

The NHS CRD






Oesophagectomy CINAHL

1) Oesophagectomy and Centrali?ation

2) Oesophagectomy and Regionali?ation

3) Oesophagectomy and Surgical Volume

4) Oesophagectomy and Hospital Volume

5) Oesophagectomy and Surgeon Volume








1) Oesophagectomy

2) 1 and Centrali*

3) 1 and Regionali*




Embase / Medline

1) * esophagectomy

2) exp esophagectomy

3) esophagectomy

4) Centrali$

5) Regionali$

6) Surgical Volume

7) Hospital Volume

8) Surgeon Volume


10) exp. Mortality

11) 1 or 2 or 3

12) 11 and 4 and 9

13) 11 and 5 and 9

14) 11 and 6 and 9

15) 11 and 7 and 9

16) 11 and 8 and 9

17) 11 and 4 and 10

18) 11 and 5 and 10

19) 11 and 6 and 10

20) 11 and 7 and 10

21) 11 and 8 and 10

The NHS CRD






Prostatectomy CINAHL

1) Prostatectomy and Centrali?ation

2) Prostatectomy and Regionali?ation

3) Prostatectomy and Surgical Volume

4) Prostatectomy and Hospital Volume

5) Prostatectomy and Surgeon Volume








1) Prostatectomy

2) 1 and Centrali*

3) 1 and Regionali*




Embase / Medline

1) * Prostatectomy

2) exp [Prostatectomy]

3) Prostatectomy

4) Centrali$

5) Regionali$

6) Surgical Volume

7) Hospital Volume

8) Surgeon Volume


10) exp. Mortality

11) 1 or 2 or 3

12) 11 and 4 and 9

13) 11 and 5 and 9

14) 11 and 6 and 9

15) 11 and 7 and 9

16) 11 and 8 and 9

17) 11 and 4 and 10

18) 11 and 5 and 10

19) 11 and 6 and 10

20) 11 and 7 and 10

21) 11 and 8 and 10

The NHS CRD






Documents

APPENDIX A – HIERARCHY OF EVIDENCE · Appendix A – Hierarchy Of Evidence ... Record linkage study. ... by centralized VA patient treatment file data versus hospital-based chart