Effects of bariatric surgery on morbidity and mortality in severe obesity

C O M M E N T A R Y

Effects of bariatric surgery on morbidity and mortality insevere obesity

Jessica Chang Bsc(Med) MBBS, BND and Gary Wittert MBBch, MD, FRACPDiscipline of Medicine, The University of Adelaide, Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide,South Australia, Australia

AbstractBackground Obesity is associated with premature mortality, particularly when very severe and/or complicated bysignificant co-morbidities such as diabetes mellitus, cardiovascular and respiratory disease. Conventional manage-ment of obesity, namely diet, exercise, behavioural modification and pharmacotherapy has limited and poorlysustained effects on weight loss and uncertain benefits for survival.

Objectives We aimed to review the literature in to determine whether bariatric surgery for morbid obesityprolongs life.

Search Strategy A Search was conducted of data bases including Medline, Cochrane library, and Science Direct.

Results Bariatric surgery produces significant and sustained weight loss. Greater weight loss occurs with proce-dures that have both a restrictive and malabsorptive component. In addition to resolution of, or at least improvementin co-morbidities and enhanced quality of life, six studies provide compelling evidence that bariatric surgerysignificantly prolongs life, an effect which is most marked in diabetics and predominantly attributable to reductionsin death due to cardiovascular causes and cancer.

Conclusion Taken together, the cost, quality of life, and survival benefits provide a compelling argument for theprovision of bariatric surgery as a management strategy of choice for severe obesity, particularly when associatedwith diabetes mellitus, or other factors conferring a significant cardiovascular risk. The optimal procedure andstrategy for patient selection remains to be determined.

Key words: bariatric surgery, morbidity, mortality, severe obesity.

Introduction

Obesity, defined as the accumulation of excessive body fat,might have serious physical and psychological health con-sequences and lead to premature death.1 The body massindex (BMI) – weight in kilograms divided by the height inmeters squared – provides an estimate of total body fat,although it has a number of limitations.2,3 It overestimatesthe degree of obesity in individuals who are very muscular. Itis also of limited utility in pregnancy, and in the elderly it ismore useful as a measure of underweight than overweight.3

For children and adolescents (2–18 years), age and sex-specific BMI-thresholds are used to define obesity.2 Based on

BMI, obesity is divided into four classes. Class 1 or mildobesity is a BMI = 30–34.9 kg/m2, class 2 or moderateobesity is a BMI = 35–39.9 kg/m2, class 3 or morbid orsevere obesity is a BMI = 40–49.9 kg/m2, and class 4 or supermorbid obesity is a BMI � 50 kg/m2.2,4 In some ethnicgroups, the equivalent health risks occur at a lower BMI. Forexample, Asians and Aboriginals are considered to be over-weight at a BMI greater than 23 kg/m2.2 Whatever the case,there is no controversy about the definition of severe obesity,and the comorbidities, often serious, are easily identifiable.

Impact of obesity on health

Studies have generally reported a linear or curvilinear rela-tionship between BMI and mortality risk in adults starting aslow as 22 kg/m2.2 Even mild degrees of obesity have adversehealth outcomes and are associated with diminishedlongevity.3,5–10 Obesity is associated with type 2 diabetes

Correspondence: Professor Gary Wittert, Discipline of Medicine,Level 6 Eleanor Harrald Building, Royal Adelaide Hospital, NorthTerrace, Adelaide, SA 5000, Australia. Email: [email protected]

doi:10.1111/j.1744-1609.2009.00123.x Int J Evid Based Healthc 2009; 7: 43–48

© 2009 The AuthorsJournal Compilation © Blackwell Publishing Asia Pty Ltd

mellitus (T2DM), hypertension, cardiovascular disease,obstructive sleep apnoea, reproductive and lower urinarytract disorders, various malignancies, osteoarthritis, gastro-oesophageal reflux, liver disease and gallstones.2,4,11 The riskof developing one or more and the severity of these disor-ders increases almost linearly in relation to the degree ofobesity.2 Psychosocial effects include impaired body image,reduced acceptance from colleagues, employment discrimi-nation and, not mobility, as a result of severe obesity, com-pound of the psychosocial consequences. Moreover the veryseverely obese might find difficulty in accessing adequatemedical care because of the limitations of wheel chairs, beds,operating theatre tables and inability to fit standard imagingequipment.12 The life expectancy of a severely obese personis reduced by an estimated 5–20 years.13,14 Obesity repre-sents one of the major causes of preventable death.7,15,16

Prevalence and costs

Obesity is now a global epidemic with increasing prevalencein both developed and developing countries.4,17,18 In Austra-lia, in 2005, 3.24 million adults were estimated to be obese– 1.52 million, male (15.1%) and 1.72 million, female(16.8%).2 In South Australia, during the period 1991–2006,class 3 obesity increased by over 400% (0.6–3.3%); this wasby far the greatest increase in obesity prevalence in anycategory.19 A similar trend is being seen in the USA.20

In the USA, in 2000, direct healthcare costs attributed toobesity were in excess of $US56 billion, and while class 3obesity accounted for 3% of overall obesity prevalence, itresulted in approximately 20% of the total expenditures.21 InAustralia, the total financial cost of obesity in 2005 wasestimated at $A3.767 billion, with $A1.73 billion (45%)attributable to productivity losses, $A873 million (23%)because of direct healthcare costs and $A804 million (21%)because of carer costs. The net cost of lost well-being was$A17.2 billion, bringing the total cost of obesity in Australia,in 2005 to $A21 billion.2 In Australia, in 2005, the healthcarecost of obesity-related comorbidities was calculated to be$A116.1 million, $A428.3 million, $A221.3 million and$A107.3 million attributable to T2DM, cardiovasculardisease, osteoarthritis and malignancies respectively.2 Theindirect healthcare cost because of obesity-related comor-bidities was far greater than the direct cost to the healthsystem with greater than $A1 billion, $A962 million,$A633 million and $A221.5 million attributable to T2DM,cardiovascular disease, osteoarthritis and malignanciesrespectively.2

Management of obesity

Broadly, weight loss strategies are divided into those withprimarily a lifestyle management approach and those with asurgical approach, which should, but does not always,include a robust lifestyle component.4,11,18,22 Lifestyle man-agement includes strategies, such as diet, exercise, behav-iour and variably the addition of pharmacotherapy.4,18,22

Surgical treatment (i.e. bariatric surgery) is, at the current

time, the only management strategy that reliably results inboth substantial and sustainable loss of weight.1,11,17,18,22

Conventional management of obesity

In virtually all studies of dietary, therapy there is weightregain after a period of weight loss, and sustained weightloss is very rare.18 Low-calorie diets (3360–6300 J/day) andvery-low-calorie diets (<3360 J/day) achieve weight loss byreducing energy intake below energy expenditure. Low-calorie diets can reduce bodyweight by an average of 8%over a 6-month period.22 Very-low-calorie diets result in agreater weight reduction of 15–25% after 3–6 months, butlong-term results are modest with 9% weight reduction after1 year and 5% after 4 years.23

Physical activity alone achieves only modest weight losswhich is at best 2–3% of bodyweight,22,24 and it is moreeffective and arguably essential for the maintenance ofweight loss.18,25 Combination strategies using diet, exerciseand behaviour therapy have been shown to be more effec-tive in the short term than either diet or exercise alone.22 Anintensive intervention, such as the Diabetes PreventionProgram, resulted in a mean weight loss of 4.1 kg in the60% of subjects for whom follow up was available after3.2 years.26

Current options for pharmacotherapy are limited by effi-cacy, compliance, cost and side-effect profiles. Weight losspharmacotherapy is of greatest utility for the maintenance ofweight loss, but only so long as drug use continues. Over aperiod of 4–5 years, orlistat has an acceptable side-effectprofile with augmented weight loss and the prevention ofT2DM resulting from lifestyle measures. The data from5-year outcome studies using sibutramine and rimonabantare awaited.27

Bariatric surgery

In 1991, the National Institutes of Health Consensus Devel-opment Panel outlined that bariatric surgery is indicatedwhen the BMI > 40 kg/m2 or when the BMI > 35 kg/m2 inthe presence of high-risk comorbid conditions.28 Bariatricsurgery might be of a restrictive or malabsorptive nature, orboth.11,22 Restrictive procedures cause early satiety by cre-ation of a small gastric pouch which leads to decreasedcaloric intake and prolong satiety by creation of a smalloutlet from the pouch.22 Examples include the laparoscopicadjustable gastric band (LAGB) and the vertical banded gas-troplasty (VBG).22 Significant dietary compliance is requiredas the intake of high-calorie liquids or soft foods are notinhibited and will result in failure to weight lose.22 Benefitsinclude technical simplicity with no anastomoses or bypassesof any part of the intestinal tract, and therefore nutritionaldeficiencies are rare.22 Disadvantages include less weight losscompared with malabsorptive procedures and more latefailures because of pouch dilatation, technical problemsrelated to the band or maladaptive eating behaviour.22

Malabsorptive procedures induce decreased absorption ofnutrients by shortening the functional length of the small

44 J Chang and G Wittert


intestine, thereby inducing negative energy balance andsubsequent weight loss.29 Examples include jejunoilealbypass which is no longer carried out because of substantialcomplications and bilio-pancreatic diversion (BPD) with orwithout duodenal switch. Benefits include significant weightloss when compared with restrictive procedures, and theweight loss is less dependent on dietary compliance; this isoffset by significant metabolic and nutritional complica-tions.11,22 The Roux-en-Y gastric bypass (RYGB) has both arestrictive and a malabsorptive component. A small gastricpouch restricts oral intake, and the small bowel reconfigu-ration assists weight loss by mild malabsorption.11,22

Effects of bariatric surgery on weight

On average, bariatric surgery results in a total weight loss of20–40 kg and a 10–15 kg/m2 reduction in BMI.30,31 Exactpercentages vary across the studies, but the overall pattern isconsistent with the highest excess weight loss (75–80%)achieved with BPD, followed by RYGB (60–70%) and theleast (44–68%) with restrictive surgical procedures (VBG orLAGB).32 The Swedish Obesity Study (SOS), in which 2010obese subjects (BMI > 34 kg/m2 in men and BMI > 38 kg/m2

in women) who self-selected themselves into one of threesurgical intervention groups (VBG, 1369 subjects; Band, 376subjects; RYGB, 265 subjects) were compared with a lifestylemanagement group (2037 subjects), is the only prospectivecontrolled surgical interventional trial. After 15 years, totalweight loss was highest (32%) in the RYGB group, 25% inthe VBG group and the least (20%) in the group in which aband was used, although this was not the same as theadjustable band currently in widespread use.33 Nevertheless,comparable data from a randomised trial of 100 patientsshowed that excess weight loss at 3 years was 58.9% versus39% in response to the VBG and LAGB respectively.34 In tworandomised clinical trials collectively enrolling 231 patients,patients assigned to the RYGB had more substantial weightloss compared with those in the VBG group: 42.43 kg versus34.45 kg at 12 months and 39.73 kg versus 30.65 kg at36 months.30,35,36 The BPD which results in the greatestweight loss is also accompanied by the highest complicationrate and thus is neither widely used nor studied in clinicaltrials.17

Effects of bariatric surgery onobesity-related comorbidities

Bariatric surgery results in substantial weight loss accompa-nied by improved quality of life and amelioration of comor-bidities in patients with morbid obesity.32 A meta-analysis ofobservational studies showed that bariatric surgery led tothe resolution of T2DM in 76.8%, hypertension in 61.7%and obstructive sleep apnoea in 85.7% of patients.31

The improvement in glycaemic control in T2DM is depen-dent on the type of procedure, but the other beneficialeffects on other comorbidities are procedure independent.The particularly beneficial effects on glucose metabolismoccur in response to those procedures with a malabsorptive

component, such as the RYGB. This is probably the result ofboth decreased nutrient intake and absorption, as well asincreases in gut hormones, such as the incretins, glucagon-like peptide and glucose-dependent insulinotrophicpolypeptide.17,37,38 Over the longer term, the benefits forglucose metabolism are also the result of improvement ininsulin sensitivity and beta-cell function, related to surgicallyinduced weight loss. Dixon et al. examined the effects of theLAGB on diabetes control in 60 obese patients with T2DMand BMI 30–40 kg/m2 who were treated in an unblindedrandomised controlled trial. Half-received conventional dia-betes treatment focusing on weight loss by lifestyle changesand the intervention group received LAGB in addition totheir usual care. Remission of T2DM was seen in 73% of thesurgical group compared with only 13% of the convention-ally treated group. The surgically treated group lost 20.7%of initial weight compared with 1.7% in the conventionallytreated group at 2 years of follow up.39 This effect is alsoseen in patients with impaired glucose tolerance with moststudies reporting 99–100% prevention of progression todiabetes.40 Remission of diabetes is related to the degree ofweight loss, and there was no special effect of the LAGB onglucose homeostasis; the RYGB is associated with the highestrecovery rate from T2DM.18

Effects of bariatric surgery onlong-term mortality

Six studies have now reported data relating to the effects ofbariatric surgery on long-term mortality (Table 1). In theSOS, the mean weight loss in the surgical cohort wasmaximal after 1–2 years with some weight gain thereafter inall surgical groups which reached a plateau at 8–10 years.Mean total weight loss was 32%, 25% and 20% for theRYGB, VGB and Band groups respectively. In contrast meanweight of the control group increased by 0.1% and 1.6% at2 and 10 years respectively. At 10.9 years of follow up witha follow-up rate of 99.9%, the adjusted overall mortality wasreduced in the surgical group by 31.6% primarily because ofa decrease in myocardial infarction, sudden death andcancer. There was no effect on the incidence of stroke, andmoreover the reduction of myocardial infarction and overallmortality occurred almost exclusively in diabetic patients.33

A retrospective cohort study by Christou et al. compared1035 patients who underwent bariatric surgery with 5746matched controls who were identified from a populationdatabase; both cohorts were followed for a maximum of5 years. The majority of the procedures were open RYGB(79%), 19% VBG (35% of which were subsequently con-verted to open RYGB because of complications) and 2%laparoscopic RYGB. There was a 67.1% mean percentageexcess weight loss, 34.6% mean percentage change in BMI,and the mortality at 5 years was decreased by 89% (0.68%in the bariatric surgery cohort compared with 6.17% in thecontrols).1 The impact of the composition of the controlgroup or practice patterns, particularly the use of cardiovas-cular preventive drugs, might have contributed to the hugedifference between the two cohort studies. While this is a

Effects of bariatric surgery 45


Tab

le1

Com

par

ison

ofst

udie

sex

amin

ing

effe

cts

ofw

eigh

tlo

sson

mor

talit

y

Chr

isto

uet

al.1

Ada

ms

etal

.41Fl

uman

dD

ellin

ger42

Sjos

trom

etal

.33Pe

eter

set

al.43

Buse

tto

etal

.44

Year

ofp

ublic

atio

n20

0420

0720

0420

0720

0720

07Ye

ars

ofre

crui

tmen

t19

86–2

002

1984

–200

219

87–2

001

1987

–200

119

94–2

005

1994

–200

1Su

rgic

alp

roce

dure

sus

edO

pen

RYG

BLa

pRY

GB

VBG

RYG

BRY

GB

VBG

Band

RYG

B

LAG

BLA

GB

Typ

eof

stud

yRe

tros

pec

tive

coho

rtRe

tros

pec

tive

coho

rtRe

tros

pec

tive

coho

rtPr

osp

ectiv

eco

ntro

lled

inte

rven

tion

tria

lO

bser

vatio

nal

Obs

erva

tiona

l

No

ofsu

rgic

alp

atie

nts

1035

7925

3328

2010

(tot

al)

1369

(VBG

)37

6(B

and)

265

(RYG

B)

966

821

No

ofco

ntro

ls57

4679

2562

781

2037

2119

821

Follo

wup

(yea

rs)

57.

11

10.9

26

(sur

gica

l)8

(con

trol

)M

orta

lity

redu

ctio

n(%

)89

4033

31.6

7262

P<

0.00

1P

<0.

001

P=

0.04

Haz

ard

ratio

0.11

Haz

ard

ratio

0.60

Haz

ard

ratio

0.67

Haz

ard

ratio

0.76

Haz

ard

ratio

0.28

Haz

ard

ratio

0.38

95%

CI

0.04

–0.2

795

%C

I0.

45–0

.67

95%

CI

0.54

–0.8

595

%C

I0.

59–0

.99

95%

CI

0.10

–0.8

595

%C

I0.

17–0

.85

Wei

ght

loss

(%,

surg

ical

coho

rt)

67.1

32(R

YGB)

25(V

BG)

20(B

and)

5839

.8�

17.9

(at

1ye

ar)

37.2

�23

.8(a

t5

year

s)

Tabl

e1

sum

mar

ises

the

resu

ltsof

six

stud

ies

ofva

ryin

gm

etho

dth

atex

amin

edou

tcom

esof

baria

tric

surg

ery

in16

085

pat

ient

s.Si

gnifi

cant

redu

ctio

nsin

mor

talit

yof

31.6

–89%

occu

rred

over

per

iods

offo

llow

upth

atra

nged

1–10

.9ye

ars.

CI,

confi

denc

ein

terv

al;

LAG

B,la

par

osco

pic

adju

stab

lega

stric

band

;RY

GB,

Roux

-en-

Yga

stric

byp

ass;

VBG

,ve

rtic

alba

nded

gast

rop

last

y.



substantially higher reduction in mortality rate as comparedwith the SOS, the majority of the surgical procedures in theSOS were VBG and Bands which are both associated withlower weight loss and a more modest effect to reverse T2DMcompared with the RYBG.1 This, as well as subject selection(those who are fat but metabolically fit), might account forthe lesser reduction in mortality in the SOS study as com-pared with the Christou study which primarily used RYGBand conversion of failed VBG to RYGB.1 It seems more likely,however, that the Christou study might be an overestimateof the effects of bariatric surgery on mortality as a 27%reduction in mortality has been reported 15 years after aRYBG based on a retrospective analysis of 3328 obesitysubjects aged 18–25 who were compared with 62 781 age-matched controls. There was a 33% reduction in mortality at1-year post-surgery, and at 15 years 16.3% of controls haddied as compared with 11.8% of RYBG patients.33,42

The largest study to be reported had an 18-year follow upand was similarly a retrospective cohort study, where 7925patients undergoing RYGB in a single practice were com-pared with 7925 population-based controls matched forage, sex and BMI. Follow up began 1-year post-surgery. Theoccurrence of death was determined by follow up andsearching of the National Death Registry. The gastric bypasscohort had a 40% reduction in all-cause mortality at7.1 years of follow up. Deaths because of diabetes decreasedby 92% and those because of ischaemic heart disease andcancer were reduced by 56% and 60% respectively. In con-trast, deaths because of suicide, accidents and poisonings ofundetermined intent were 58% higher in the surgicalcohort. The reason for this is unclear, but the potentialoverall mortality reduction because of bariatric surgery isdecreased.41,45

Two studies have reported mortality outcomes afterLAGB surgery, both observational and using conveniencecontrols. Peeters et al. compared mortality data from twoMelbourne cohorts, a surgical cohort of 966 patients andan established population-based cohort of 2119 obesesubjects. For both cohorts, only those between 20 and70 years of age and a BMI greater than 35 kg/m2 wereincluded. Mean excess weight loss in response to the LAGBwas 58% at 2 years. There was a 72% mortality reductionin the surgically treated group with four deaths in the sur-gical cohort compared with 225 deaths in the population-based cohort. However, 23 individuals from the surgicalcohort were lost to follow up, and accordingly the mortalityrate might be higher. Another limitation to this study is thatboth cohorts were assumed to represent the same obesepopulation. The population cohort consisted of voluntaryparticipants with an oversampling of the Mediterraneanpopulation, while the surgical cohort consisted of individu-als who had private health insurance and had attemptedweight loss before surgery. Thus the results might havebeen biased towards a greater survival advantage in thesurgical cohort.45,43 The second of the two studies com-pared the long-term mortality of 821 obese patients whowere treated with LAGB surgery and 821 age, sex and BMI-matched controls from the Italian Study Group on Morbid

Obesity. Follow up was ~6 years in the surgical cohort and~8 years in the controls. Weight loss was stable at 40%both at 1 year and 5 years post-LAGB, and there was 62%reduction in the 5-year mortality rate in the LAGB group.The mortality rate might, however, have been higher in theLAGB group as follow up was incomplete.44

Conclusions

The evidence that bariatric surgery confers a survival benefitfor patients with morbid obesity is compelling. This,together with the data relating to resolution of, or at leastsubstantial reduction in, obesity-related disease, along withimproved quality of life and productivity and reduction inhealthcare costs, suggests that bariatric surgery is the man-agement strategy of choice for extreme obesity. Whether thesurvival advantage is a direct result of surgically inducedweight loss per se or because of the indirect effects of weightloss on improvement in particular comorbidities requiresmore detailed subgroup analyses, as this has implications forselection of the most suitable patients.

There is insufficient data to conclude superiority of LAGBover RYBG for mortality, and vice versa. A controlled head tohead study would be required. Given the superiority forweight loss and data related to outcomes for comorbiditiesand complications, the RYGB remains the gold standardsurgical treatment for obesity, at least for those with morbidobesity and T2DM.17,22,37

Competing interests

None.

References1. Christou NV, Sampalis JS, Liberman M et al. Surgery decreases

long-term mortality, morbidity, and health care use in morbidlyobese patients. Ann Surg 2004; 240: 416–23; discussion 23–4.

2. Access Economics and Diabetes Australia. The Economic Costs ofObesity in Australia. Canberra, 2006.

3. Freedman DM, Ron E, Ballard-Barbash R et al. Body mass indexand all-cause mortality in a nationwide US cohort. Int J Obes(2005) 2006; 30: 822–9.

4. Hager C. Quality of life after Roux-en-Y gastric bypass surgery.AORN J 2007; 85: 768, 70–5, 77–8.

5. Yan LL, Daviglus ML, Liu K et al. Midlife body mass index andhospitalization and mortality in older age. JAMA 2006; 295:190–8.

6. Jee SH, Sull JW, Park J et al. Body mass index and mortality inKorean men and women. N Engl J Med 2006; 355: 779–87.

7. van Dam RM, Willett WC, Manson JE et al. The relationshipbetween overweight in adolescence and premature death inwomen. Ann Intern Med 2006; 145: 91–7.

8. Price GM, Uauy R, Breeze E et al. Weight, shape, and mortalityrisk in older persons: elevated waist–hip ratio, not high bodymass index, is associated with a greater risk of death. Am J ClinNutr 2006; 84: 449–60.

9. Adams KF, Schatzkin A, Harris TB et al. Overweight, obesity, andmortality in a large prospective cohort of persons 50 to 71 yearsold. N Engl J Med 2006; 355: 763–78.

10. Sjostrom LV. Mortality of severely obese subjects. Am J Clin Nutr1992; 55 (Suppl. 2): 516S–23.

Effects of bariatric surgery 47


11. Bult MJ, van Dalen T, Muller AF. Surgical treatment of obesity.Eur J Endocrinol 2008; 158: 135–45.

12. Sturm R. Increases in clinically severe obesity in the UnitedStates, 1986–2000. Arch Intern Med 2003; 163: 2146–8.

13. Peeters A, Barendregt JJ, Willekens F et al. Obesity in adulthoodand its consequences for life expectancy: a life-table analysis.Ann Intern Med 2003; 138: 24–32.

14. Fontaine KR, Redden DT, Wang C et al. Years of life lost due toobesity. JAMA 2003; 289: 187–93.

15. Mokdad AH, Serdula MK, Dietz WH et al. The continuingepidemic of obesity in the United States. JAMA 2000; 284:1650–1.

16. Allison DB, Fontaine KR, Manson JE et al. Annual deaths attrib-utable to obesity in the United States. JAMA 1999; 282:1530–8.

17. Livingston EH. Obesity and its surgical management. Am J Surg2002; 184: 103–13.

18. Bessesen DH. Update on obesity. J Clin Endocrinol Metab 2008;93: 2027–34.

19. Howard NJ, Taylor AW, Gill TK, Chittleborough CR. Severeobesity: investigating the socio-demographics within theextremes of body mass index. Obes Res Clin Pract 2008; 2: 51–9.

20. Sturm R. Increases in morbid obesity in the USA: 2000–05.Public Health 2007; 121: 492–6.

21. Arterburn DE, Maciejewski ML, Tsevat J. Impact of morbidobesity on medical expenditures in adults. Int J Obes (2005)2005; 29: 334–9.

22. Fisher BL, Schauer P. Medical and surgical options in the treat-ment of severe obesity. Am J Surg 2002; 184: 9S–16.

23. Tsai AG, Wadden TA. Systematic review: an evaluation of majorcommercial weight loss programs in the United States. AnnIntern Med 2005; 142: 56–66.

24. Wood PD, Stefanick ML, Dreon DM et al. Changes in plasmalipids and lipoproteins in overweight men during weight lossthrough dieting as compared with exercise. N Engl J Med 1988;319: 1173–9.

25. Miller WC, Koceja DM, Hamilton EJ. A meta-analysis of the past25 years of weight loss research using diet, exercise or diet plusexercise intervention. Int J Obes Relat Metab Disord 1997; 21:941–7.

26. Hamman RF, Wing RR, Edelstein SL et al. Effect of weight losswith lifestyle intervention on risk of diabetes. Diabetes Care2006; 29: 2102–7.

27. Wittert GA, Caterson ID, Finer N. Clinical effectiveness of medi-cations for weight loss. Obes Res Clin Pract 2007; 1: 1–5.

28. NIH conference. Gastrointestinal surgery for severe obesity.Consensus Development Conference Panel. Ann Intern Med1991; 115: 956–61.

29. Schneider BE, Mun EC. Surgical management of morbidobesity. Diabetes Care 2005; 28: 475–80.

30. Maggard MA, Shugarman LR, Suttorp M et al. Meta-analysis:surgical treatment of obesity. Ann Intern Med 2005; 142: 547–59.

31. Buchwald H, Avidor Y, Braunwald E et al. Bariatric surgery: asystematic review and meta-analysis. JAMA 2004; 292: 1724–37.

32. Lunca S, Pertea M, Bouras G et al. Morbid obesity: a surgicalperspective. Rom J Gastroenterol 2005; 14: 151–8.

33. Sjostrom L, Narbro K, Sjostrom CD et al. Effects of bariatricsurgery on mortality in Swedish obese subjects. N Engl J Med2007; 357: 741–52.

34. Morino M, Toppino M, Bonnet G et al. Laparoscopic adjustablesilicone gastric banding versus vertical banded gastroplastyin morbidly obese patients: a prospective randomizedcontrolled clinical trial. Ann Surg 2003; 238: 835–41; discussion41–2.

35. Sugerman HJ, Starkey JV, Birkenhauer R. A randomized prospec-tive trial of gastric bypass versus vertical banded gastroplasty formorbid obesity and their effects on sweets versus non-sweetseaters. Ann Surg 1987; 205: 613–24.

36. Hall JC, Watts JM, O’Brien PE et al. Gastric surgery formorbid obesity. The Adelaide Study. Ann Surg 1990; 211: 419–27.

37. Meneghini LF. Impact of bariatric surgery on type 2 diabetes.Cell Biochem Biophys 2007; 48: 97–102.

38. Laferrere B, Heshka S, Wang K et al. Incretin levels and effect aremarkedly enhanced 1 month after Roux-en-Y gastric bypasssurgery in obese patients with type 2 diabetes. Diabetes Care2007; 30: 1709–16.

39. Dixon JB, Dixon ME, O’Brien PE. Quality of life after lap-bandplacement: influence of time, weight loss, and comorbidities.Obes Res 2001; 9: 713–21.

40. Schernthaner G, Morton JM. Bariatric surgery in patients withmorbid obesity and type 2 diabetes. Diabetes Care 2008; 31(Suppl. 2): S297–302.

42. Flum DR, Dellinger EP. Impact of gastric bypass operation onsurvival: a population-based analysis. J Am Coll Surg 2004; 199:543–51.

41. Adams TD, Gress RE, Smith SC et al. Long-term mortality aftergastric bypass surgery. N Engl J Med 2007; 357: 753–61.

45. Abstracts of the 10th International Congress on Obesity (ICO).September 3–8, 2006. Sydney, Australia. Obes Rev 2006; 7(Suppl. 2): 1–352.

43. Peeters A, O’Brien PE, Laurie C et al. Substantial intentionalweight loss and mortality in the severely obese. Ann Surg 2007;246: 1028–33.

44. Busetto L, Mirabelli D, Petroni ML et al. Comparative long-termmortality after laparoscopic adjustable gastric banding versusnonsurgical controls. Surg Obes Relat Dis 2007; 3: 496–502;discussion.



Documents

Effects of bariatric surgery on morbidity and mortality in severe obesity