Life Expectancy Benefits of Gastric Bypass Surgery

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Abstract
Bariatric surgery is the most effective treatment for achieving sustained weight loss in morbidly obese patients. Although the use of gastric bypass is growing rapidly, the potential life expectancy benefits of the procedure are unknown. We created a Markov decision analysis model to examine the effect of gastric bypass surgery on life expectancy in morbidly obese patients (body mass index [BMI] = 40 kg/m2). Input assumptions for the model were obtained from published life tables (baseline mortality risks), epidemiologic studies (obesity-related excess mortality), and large case series (surgical outcomes). In our baseline analysis, a 40-year-old woman (BMI = 40 kg/m2) would gain 2.6 years of life expectancy by undergoing gastric bypass (38.7 years versus 36.2 years without surgery). In sensitivity analysis, life-years gained with surgery remained substantial when assumptions were varied across reasonable ranges for surgical mortality risk (1.0-3.0 years) and effectiveness (0.9-4.4 years). Life-years gained with gastric bypass surgery did not vary considerably by age and sex subgroups. Relative to other major surgical procedures, gastric bypass for morbid obesity is associated with substantial gains in life expectancy. Long- term data from prospective studies are needed to confirm this finding.