A Landmark Study on bariatric surgery !!

This is a landmark study from Oslo University Hospital Aker and University of Oslo, Oslo, Norway, and Sahlgrenska University Hospital, Gothenburg, Sweden and Oslo Diabetes Research Centre. The authors compared in a randomized  study two different bariatric surgical procedures in extremely overweight (BMI between 50-60) and  relatively young persons.They published their findings in one of the premier medical journals in the world, Annals of Internal medicine (impact factor 16.2, highest of any journals in internal medicine worldwide !)

Gastric bypass and duodenal switch are currently performed bariatric surgical procedures. Uncontrolled studies suggest that duodenal switch induces greater weight loss than gastric bypass.  The aim was to determine whether duodenal switch leads to greater weight loss and more favorable improvements in cardiovascular risk factors and quality of life than gastric bypass.

The primary outcome was the change in BMI after 2 years. Secondary outcomes included anthropometric measures; concentrations of blood lipids, glucose, insulin, C-reactive protein, and vitamins; and health-related quality of life and adverse events.

Results: Fifty-eight of 60 participants (97%) completed the study. The mean reductions in BMI were 17.3 kg/m2 (95% CI, 15.7 to 19.0 kg/m2) after gastric bypass and 24.8 kg/m2 (CI, 23.0 to 26.5 kg/m2) after duodenal switch (mean between-group difference, 7.44 kg/m2 [CI, 5.24 to 9.64 kg/m2]; P < 0.001). Total cholesterol concentration decreased by 0.24 mmol/L (CI, −0.03 to 0.50 mmol/L) (9.27 mg/dL [CI, −1.16 to 19.3 mg/dL]) after gastric bypass and 1.07 mmol/L (CI, 0.79 to 1.35 mmol/L) (41.3 mg/dL [CI, 30.5 to 52.1 mg/dL]) after duodenal switch (mean between-group difference, 0.83 mmol/L [CI, 0.48 to 1.18 mmol/L]; 32.0 mg/dL [CI, 18.5 to 45.6 mg/dL]; P < 0.001). Reductions in low-density lipoprotein cholesterol concentration, anthropometric measures, fat mass, and fat-free mass were also greater after duodenal switch (P ≤ 0.010 for each between-group comparison). Both groups had reductions in blood pressure and mean concentrations of glucose, insulin, and C-reactive protein, with no between-group differences. The duodenal switch group, but not the gastric bypass group, had reductions in concentrations of vitamin A and 25-hydroxyvitamin D. Most Short Form-36 Health Survey dimensional scores improved in both groups, with greater improvement in 1 of 8 domains (bodily pain) after gastric bypass. From surgery until 2 years, 10 participants (32%) had adverse events after gastric bypass and 18 (62%) after duodenal switch (P = 0.021). Adverse events related to malnutrition occurred only after duodenal switch.

They conclude that duodenal switch surgery was associated with greater weight loss, greater reductions of total and low-density lipoprotein cholesterol concentrations, and more adverse events. Improvements in other cardiovascular risk factors and quality of life were similar after both procedures.

( Torgeir T. Søvik, Erlend T. Aasheim, Osama Taha, My Engström, Morten W. Fagerland, Sofia Björkman, Jon Kristinsson, Kåre I. Birkeland, Tom Mala, Torsten Olbers, Weight Loss, Cardiovascular Risk Factors, and Quality of Life After Gastric Bypass and Duodenal Switch Ann.Intern.Med. 2011;155:281-91)


The journal considered the study so important that they had an editorial on the paper by a well known expert in the field professor Edward H. Livingston from University of Texas Southwestern Medical Center. His heading is Primum Non Nocere (first do not harm). After praising the study, he is quite blunt:

“To do no harm has been a guiding tenet of medicine for millennia. In this context, bariatric surgery warrants serious consideration. Bariatric operations undoubtedly induce weight loss, but at what cost? Consideration of the balance between benefits and harms calls into question the overall utility of bariatric surgery and, most important, what the appropriate end points should be. Procedures that induce intestinal malabsorption are unnatural and inherently dangerous.

He follows up: A most striking observation in Søvik and colleagues’ report is the very high complication rate in both groups: 32% for gastric bypass and 62% for duodenal switch. The spectrum of complications seemed to be related to the operations and their expected consequences rather than to technical factors. Patients in both groups experienced vomiting, abdominal pain, and diarrhea. Both groups included patients with small bowel obstructions and hospital readmissions. A very worrisome observation was that among the 29 patients in the duodenal switch group, there were 3 cases of protein calorie malnutrition, 2 cases of night blindness necessitating treatment, and 1 case severe iron deficiency requiring iron infusion;

How, then, to interpret Søvik and colleagues’ findings? It seems clear that we should seriously question whether there is any role for the duodenal switch operation. It results in nearly double the complication rate, and its complications are very real and very severe. The benefit of some additional weight loss does not seem worth the tradeoffs, because greater weight loss does not seem to change the anticipated long-term outcomes for bariatric surgery. From a metabolic perspective, although Søvik and colleagues found a larger change in cholesterol levels that was attributable to duodenal switch, these values were near-normal to begin with. Finally, if the reason for performing bariatric surgery in metabolically healthy patients is to improve longevity, one needs to carefully consider the evidence base. Absolute improvements in mortality attributable to bariatric surgery in cohorts similar to those in Søvik and colleagues’ study are minimal—1.3% during 10.9 years of follow-up in the Swedish Obese Subjects of obesity surgery (11) and 1.4% in a study of gastric bypass (12)—and a survival benefit was nonexistent for metabolically high risk patients (9).

Short- and long-term complications of bariatric operations are inevitable. Given the very high rate of lifelong complications and the minimal effect of these procedures on overall survival, improved longevity is probably not a reasonable justification for performing them. Bariatric operations should be done to control an immediate medical problem that surgically induced weight loss is expected to resolve; examples include diabetes and sleep apnea. In this context, weight loss per se is not the goal, but rather control of comorbid conditions. Thus, dr. Livingston suggests that duodenal switch is not an appropriate operation because the added weight loss compared with gastric bypass is offset by complications that far outweigh any potential”

The study thus stirred controversy which an outstanding study should always do.

Congratulations to Torgeir, Erlend,  Jon and Kåre !

The study was mainly supported by South-Eastern Norway Regional Health Authority