ACS trauma centre designation and outcomes of post-traumatic ARDS: NTDBanalysis and implications for trauma quality improvement

Gustavo Recinos, Joseph J. DuBose *, Pedro G.R. Teixeira, Galinos Barmparas, Kenji Inaba, David Plurad,D.J. Green, Demetrios Demetriades, Howard Belzberg

Los Angeles County Hospital/University of Southern California School of Medicine, Los Angeles, CA, United States

Injury, Int. J. Care Injured 40 (2009) 856–859

A R T I C L E I N F O

Article history:

Accepted 6 November 2008

Keywords:

ARDS

ALI

Outcomes

Trauma

Critical care

ACS verification

A B S T R A C T

Background: Several authors have examined the relationship between outcomes following severe trauma

and American College of Surgeons (ACS) trauma centre designation. Little is known, however, about the

association between ACS level and outcomes following complications of trauma.

Methods: The National Trauma Databank (NTDB, v. 5.0) was queried to identify adult (Age �18) trauma

patients developing post-traumatic ARDS, who were admitted to either ACS level 1 or level 2 trauma

centres from 2000 to 2004. Patients transferred between institutions and injuries following burns were

excluded. Univariate analysis was used to assess differences between those patients admitted to ACS level

1 and level 2 facilities. Adjusted mortality was derived using logistic regression analysis.

Results: A total of 902 adult trauma patients with ARDS after 48 h of mechanical ventilation were

identified from the NTDB. Five hundred and thirty six patients were admitted to a level 1 ACS verified

centre and 366 to a level 2 facility. Univariate analysis revealed no statistical differences in clinical and

demographic characteristics between the two groups. On univariate comparison, patients admitted to

level 1 facilities had longer mean hospital and ICU length of stay and higher hospital related charges than

level 2 counterparts. Patients admitted to a level 1 centre were, however, significantly more likely to

achieve discharge to home. Using multivariate logistic regression, ACS level designation was shown to

have no statistical effect on mortality. Hypotension on admission and age greater than 55 were the only

independent predictors of mortality.

Conclusion: ACS trauma centre designation level is not an independent predictor of mortality following

post-traumatic ARDS.

� 2008 Elsevier Ltd. All rights reserved.

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Introduction

Since 1987, the American College of Surgeons (ACS) haseffectively employed their trauma verification programme tovalidate the care provided at trauma centres, clearly defining theoptimal resources required for designation of trauma centres intothree different levels according to available resources; as well aseducational and research commitments.3 Subsequently, NationalTrauma Databank (NTDB) studies of patients with severe trauma4

and specific critical injuries5 have demonstrated that level 1trauma centres have markedly better survival and functionaloutcomes than their level 2 counterparts. The relationshipbetween ACS verification level and outcomes following complica-

* Corresponding author. University of Southern California, 1200 North State

Street, Room 10-750, Los Angeles, CA 9003-4525, United States.

Tel.: +1 323 226 8112; fax: +1 323 226 8116.

E-mail address: jjd3c@yahoo.com (J.J. DuBose).

0020–1383/$ – see front matter � 2008 Elsevier Ltd. All rights reserved.

doi:10.1016/j.injury.2008.11.001

tions of trauma has been less well examined. ARDS remains one ofthe most worrisome complications of trauma, despite improvingoutcomes due to evidence-based interventions.7,10 The purpose ofour study was to determine the relationship between ACS traumacentre verification level and outcome of post-traumatic ARDS,highlighting the need for the demonstration of compliance withevidence-based strategies in trauma quality improvement.

Methods

We conducted a retrospective review of the National TraumaDatabank (NTDB v. 5.0) of the American College of Surgeons from2000 to 2004. The NTDB was queried to identify all adult (age �18years old) trauma patients ventilated greater than 48 h who wenton to develop ARDS. Only patients admitted to ACS level 1 and 2facilities were included for analysis. Patients involved in inter-hospital transfer and with injuries due to burn mechanisms wereexcluded.

G. Recinos et al. / Injury, Int. J. Care Injured 40 (2009) 856–859 857

Demographic elements used for analysis included age, gender,mechanism of injury (blunt vs. penetrating), ACS trauma centreverification level (level 1 or level 2), blood pressure on admission,arrival unassisted respiratory rate, admission Glasgow ComaScale (GCS), Injury Severity Score (ISS), Abbreviated Injury Scale(AIS) for chest, and the performance/timing of tracheostomy. Ouroutcomes of interest included hospital length of stay (LOS),intensive care unit (ICU) LOS, ventilator days, hospital charges andsurvival outcomes. Documented complications (bacteremia,pneumonia, renal failure and pulmonary embolism) were alsoexamined.

Patients admitted to level 1 trauma centres were comparedto those admitted to level 2 for differences in baseline clinicaland demographic characteristics. Continuous variables werecompared using the unpaired Students t-test for normallydistributed variables and the Mann–Whitney U test for variableswith skewed distribution. The chi-square or Fisher’s exact testwas used to compare categorical variables. In order to asses theimpact of the ACS verification level on mortality, all factors thatwere different between the two study groups at p < 0.2 and allfactors that were associated with mortality at p < 0.2 wereentered into a multivariable logistic regression model. Adjustedodds ratio with 95% confidence interval and adjusted p-valuewere derived.

All statistical analysis was performed using SPSS software,version 12.0, for Windows (SPSS, Inc., Chicago, IL).

Results

During the study period, 952,242 trauma cases were reported tothe NTDB, with 13,933 (1.5%) requiring mechanical ventilationgreater than 48 h. ARDS was reported in identified 902 (6.5%, 902of 13,933) of this study group. Among these, 536 patients wereadmitted to a level 1 centre and 366 admitted to a level 2institution. When clinical and demographic characteristics werecompared [Table 1], both patient groups had similar age, injurycharacteristics and clinical presentation, however, patientsadmitted to a level 1 facility less often had a chest AIS � 4 (23%vs. 29%, p = 0.04). There was no difference between the two groupsin the overall use of tracheostomy or in the performance of early(�7 days) tracheostomy.

Univariate comparison of outcomes [Table 2] revealed thatpatients admitted to a level 1 facility had a longer mean hospital(35 vs. 28 days, p = 0.002) LOS, ICU LOS (24 vs. 21; p = 0.037),increased mean days (22.2 vs. 18.3 days, p = 0.012) and higher

Table 1Comparing the demographic and clinical characteristics between adult patients treated

Total, n = 902

Age, mean � SD 45.8 � 19.0

Age � 55, % (n) 29.0% (262)

Male, % (n) 73.5% (663)

Mechanism blunt, % (n) 92.6% (835)

SBP, mean � SD 125.8 � 36.1

SBP < 90 mmHg, % (n) 19.8% (179)

First unassisted respiratory rate, mean � SD 18.4 � 9.9

GCS on admission, mean � SD 9.9 � 5.3

GCS � 8 on admission, % (n) 45.2% (408)

ISS, mean � SD 27.4 � 12.7

ISS > 15% (n) 85.0% (767)

Chest AIS � 4, % (n) 25.4% (229)

Tracheostomy, % (n) 49.0% (442)

Early tracheostomy (�7 days), %

(n/patients undergoing tracheostomy)

34.4% (152/442)

The p values for categorical variables were derived from Chi-square test or two-tailed

Student’s t-Test or Mann–Whitney test. SD: standard deviation, SBP: systolic blood pres

Scale.

mean hospital-related charges ($263,247 vs. 215,787; p = 0.001).Level one patients were, however, more likely to achievedischarge to home from the admitting facility (18.5% vs. 13.9%,p < 0.001).

The rate of complications between level 1 and level 2 did notdiffer significantly except with regards to the percentage ofpatients reported as developing pulmonary embolism (4.3% vs.1.6%, p = 0.027) and pneumonia (53.7% vs. 40.7%, p < 0.001),which proved higher in patients admitted to level 1 centres.Crude mortality did not differ between the two populations(20% vs. 18%, p = 0.37). After logistic regression to adjust formechanism of injury, GCS, hypotension on admission, age >55years old, ISS > 15 and chest AIS � 4, ACS level verification didnot have a significant impact on mortality in trauma patientswho develop ARDS (adjusted odds ratio: 1.23; 95% CI: 0.87–1.73;p = 0.25) [Table 3].

Discussion

Since the introduction of their verification programme in 1987,the ACS Committee on Trauma has verified over 200 centresaccording to a tiered level of designation. As outlined in theirpublication, Resources for Optimal Care of the Trauma Patient,3

verification of trauma centre level requires compliance withnumerous criteria. The requirements for the highest level ofverification, level 1, include adequate trauma volume and theavailability of rapid access to a number of specialised care servicesand providers. The highest proficiency in the ability to provide forICU care of high quality, safety and appropriateness must also bedemonstrated. Additionally, periodic reviews must be conductedto ensure these standards are maintained in an ongoing fashion.

Advanced ACS level verification has previously been shown tobe associated with improved outcome following significanttrauma. In a NTDB study of trauma patients with ISS >15,4

Demetriades et al. found that patients treated at level 1 facilitieshad improved survival over counterparts admitted to level 2centres. In a separate examination of patients with specific severeinjury patterns, the same group noted that patients sustainingcardiovascular and high-grade liver injuries were significantlymore likely to survive if they were treated at an ACS-verified level 1trauma facility.5 The relationship between ACS level and improve-ments in the outcomes of trauma-related complications, however,has not been well documented.

We examined the differences in outcomes following post-traumatic ARDS between ACS level 1 and level 2 facilities and

at ACS verified level 1 and level 2 trauma centres.

Level 1, n = 536 Level 2, n = 366 p-value

44.8 � 18.4 47.2 � 19.9 0.06

26.9% (144) 32.2% (118) 0.08

74.3% (398) 72.4% (265) 0.53

91.2% (489) 94.5% (346) 0.06

125.8 � 35.2 125.8 � 37.4 0.99

20.0% (107) 19.7% (72) 0.91

18.5 � 9.2 18.1 � 10.9 0.57

9.8 � 5.3 10.1 � 5.3 0.43

45.0% (241) 45.6% (167) 0.84

27.3 � 12.4 27.3 � 13.1 0.96

86.6% (464) 82.8% (303) 0.11

22.9% (123) 29.0% (106) 0.04

49.8% (267) 47.8% (175) 0.55

34.5% (92/267) 34.3% (60/175) 0.97

Fisher’s exact test; p values for continuous variables were derived from unpaired

sure, GCS: Glasgow Coma Scale, ISS: Injury Severity Score, AIS: Abbreviated Injury

Table 2Comparing outcomes between patients treated at ACS verified level 1 and level 2 trauma centres.

Total, n = 902 Level 1, n = 536 Level 2, n = 366 p-value

Deaths, % (n) 19.2% (173) 20.1% (108) 17.8% (65) 0.37

Aspiration pneumonia, % (n) 9.3% (84) 9.1% (49) 9.6% (35) 0.83

Pneumonia, % (n) 48.4% (437) 53.7% (288) 40.7% (149) <0.001

Bacteremia, % (n) 5.1% (46) 6.0% (32) 3.8% (14) 0.15

Fungal infection, % (n) 0.6% (5) 0.6% (3) 0.5% (2) 0.97

Pulmonary embolism, % (n) 3.2% (29) 4.3% (23) 1.6% (6) 0.027

Renal failure, % (n) 14.1% (127) 14.7% (79) 13.1% (48) 0.49

Discharged disposition: home, % (n) 16.6% (150) 18.5% (99) 13.9% (51) <0.001

Ventilator days, mean � SD 20.6 � 18.3 22.2 � 20.5 18.3 � 14.5 0.012

ICU days, mean � SD 22.6 � 18.9 24.0 � 21.3 20.7 � 14.4 0.037

Hospital days, mean � SD 32.4 � 26.9 35.2 � 30.8 28.3 � 19.2 0.002

Charges in US$, mean � SD $244,525 � $218,196 $263,247 � $239,956 $215,788 � $176,387 0.001

The p values for categorical variables were derived from Chi-square test or two-tailed Fisher’s exact test; p values for continuous variables were derived from Student’s t-test

or Mann–Whitney test. SD: standard deviation, ICU: Intensive Care Unit.

Table 3Adjusted odds ratio for mortality after logistic regression.

Adjusted OR (95% CI) Adjusted p-value

ACS level 1 Admission 1.23 (0.87–1.73) 0.25

GCS � 8 1.60 (1.13–2.27) 0.008

SBP < 90 mmHg 1.68 (1.14–2.49) 0.010

Age > 55 years 1.69 (1.16–2.43) 0.006

ISS > 15 1.44 (0.91–2.34) 0.13

Mechanism penetrating 1.08 (0.57–2.07) 0.79

Chest AIS > 4 1.01 (0.67–1.51) 0.97

ACS: American College of Surgeons, GCS: Glasgow Coma Scale, SBP: systolic blood

pressure, ISS: Injury Severity Score, AIS: Abbreviated Injury Scale.

G. Recinos et al. / Injury, Int. J. Care Injured 40 (2009) 856–859858

found that, while patients admitted to a level 1 centre morecommonly achieved discharge to home, admission to a centre ofhigher designation did not confer any benefit in terms of adjustedrisk of mortality. Level 1 admission was, in fact, associated withlonger mean hospital and ICU LOS, as well as increased hospitalcost. Additionally, the pneumonia rate was significantly higher inthe level 1 cohort. The value of this latter finding is limited,however, as the NTDB does not provide temporal informationregarding the onset of complications. We were, therefore, unableto determine if pneumonia was the cause, or a subsequentcomplication of post-traumatic ARDS.

ARDS remains a significant complication of trauma, with areported incidence of 11%–14%7,8 and overall mortality of up to27%.7,8 Post-traumatic ARDS appears to be decreasing in incidence,however, and outcomes following this sequela of trauma areimproving.7,10 In a study by Martin et al.7 the investigatorsdemonstrated a more than 50% reduction in the incidence of post-traumatic ARDS over a period from 2000 to 2004, with anassociated decrease in mortality. While the reasons for thisimprovement are difficult to precisely ascertain, it is clear that theefforts of the ARDS Network group and other investigators todevelop evidence-based strategies for the optimisation of ARDSoutcomes has contributed.1

The effective implementation of these evidence-based strate-gies, however, remains a challenge. For example, although theARDS Network investigators first reported a reduced mortality in amixed population of patients with ALI and ARDS ventilated withlower tidal volumes in 2000, compliance with this evidence-basedtreatment remains poor.9 We have previously reported that the useof a quality rounds checklist is an effective measure by which toimprove compliance with many evidence-based care measures inthe trauma ICU. The introduction of this tool, which includes dailydocumentation of low-tidal volume implementation for patients

with ALI/ARDS, proved a time and cost-effective methodology thatboth facilitated effective quality reporting and improved patientoutcomes.6

Unfortunately, standardised reporting of compliance withevidence-based aspects of care is not currently a specificrequirement for ACS trauma centre verification. The intersitevariability in reporting of ARDS and other complications,including potential differences in reporting rates between levelI and level II centres, is unknown. The success of ACS qualityimprovement efforts, including the National Surgical QualityImprovement Programme (NSQIP),2 has, however, highlighted thesignificant impact that these programmes can have on patientcare. The inclusion of standardised compliance reporting in therequirements for ACS verification, and possibly expansion of theNTDB or the development of a national trauma quality improve-ment programme to include this data, might result in both animportant measure for comparison of the quality of care providedbetween various ACS trauma centres and improvement in patientoutcomes.

Conclusion

ACS level 1 facilities demonstrated no adjusted survival benefitover level 2 counterparts following post-traumatic ARDS. Includ-ing requirements for the standardised reporting of compliancewith evidence-based interventions in trauma centre verificationrequirements may result in both a better measure for thecomparison of quality of care delivery and improved patientoutcomes.

Conflict of interest statement

The authors have no financial or personal relationships withany people or organisations that might inappropriately influencethis original work.

References

1. Anonymous. Available at: http://www.ardsnet.org/. Accessed February 16,2008.

2. Anonymous. National Surgical Quality Improvement Project. Available at:https://acsnsqip.org/login/default.aspx. Accessed February 16, 2008.

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