Twenty years of biliopancreatic diversion: what is the goal of the surgery?

Background: Comparative evaluation of weight loss after bariatric surgery is difficult without definition of success and without a norm for presenting results. We explored the pertinence of defining success: a residual BMI <40 or <35 kg/m(2), and the need for reporting results with stratification by initial obesity and length of follow-up.
Methods: Results of 1,271 consecutive biliopancreatic diversion (BPD) patients were compared when presented with or without stratification, and we searched for landmarks of success which would be shared by patients themselves.
Results: Presented globally, after a mean follow-up of 7.9 +/- 4.2 years, BMI decreased from 48.4 +/- 9.4 to 31.3 +/- 6.5, and only 10% and 26% of patients would have been considered failures with a residual BMI >or= 40 or >or= 35 respectively. Because heavier patients were losing less in terms of percentage ( P <0.0001) and regained weight faster ( P <0.0001), global and cumulative results failed to show a failure-rate doubling every 5 years and a very high failure-rate in heavier patients. The landmarks of BMI 40 and 35 were the same unconsciously used by patients to express their own perception of failure. For patients with an initial BMI <50, a residual BMI of 35 caused a significant drop in the degree of satisfaction from 90 to 40%. For super-obese, the same critical point was found at a BMI of 40 where satisfaction dropped from 91 to 57%.
Conclusion: Landmarks of success at BMI 40 and 35 were realistic, reasonable and coincided with patients' own expectations. Since initial obesity and duration after surgery made so much difference in results, a comparison of different surgical approaches was useless without stratification for both factors together.