Comparing the Benefits and Harms of Three Types of Weight Loss Surgery -- The PCORnet® Bariatric Study

The main aims of this study will compare the effectiveness and safety of the three most common bariatric surgical procedures: Roux-en-y gastric bypass (RYGB), adjustable gastric banding (AGB), and sleeve gastrectomy (SG). Question (Aim) 1: To what extent does weight loss and weight regain differ across the three bariatric surgical procedures at 1, 3, and 5 years? This aim addresses the primary outcome of interest among most patients seeking bariatric surgery - the differential impact of these procedures on maximum weight loss as well as the extent of longer-term weight regain. We will also explore the heterogeneity in weight loss and regain across several key subgroups that may have differential response to surgical treatment, specifically groups defined by age, race/ethnicity, baseline BMI, smoking status, and pre-operative comorbidities. Question (Aim) 2: To what extent do these bariatric procedures differ on improvements in diabetes risk at 1, 3, and 5 years? Among patients with diabetes, remission or "cure" of their disease (defined as HbA1c \<6.5% off diabetes medications) has been cited as the most important outcome of bariatric surgery. Thus, we will examine the comparative effect of these procedures on rates of diabetes remission as well as relapse (recurrence). Secondary analyses will examine the comparative impact of the procedures on glycemic control independent of diabetes remission. Question (Aim) 3: What is the frequency of major adverse events following these three different bariatric surgical procedures at 1, 3, and 5 years? We will examine four important adverse event outcome categories across the three procedures: 1) short- and long-term (1, 3, and 5 year) mortality rates, 2) a composite end point of 30-day major adverse outcomes: based on the definition used in the Longitudinal Assessment of Bariatric Surgery (LABS) study that included death; venous thromboembolism; percutaneous, endoscopic, or operative subsequent intervention; and failure to be discharged from the hospital; 3) subsequent hospitalization (any hospitalization following initial surgery); and 4) subsequent reoperation/reintervention: defined as any additional bariatric procedure and other procedures related to device removals, gastric revisions, abdominal or incisional hernia repair, laparoscopy or laparotomy, and percutaneous endoscopic gastrostomy tube placements. Question (Aim) 4: To what extent do bariatric surgery outcomes explored in Aims 1-3 differ with respect to baseline depression diagnosis at 1, 3, and 5 years after surgery? Question (Aim) 5: To what extent do bariatric surgery outcomes explored in Aims 1-3 differ with respect to race and ethnicity at 1, 3, and 5 years after surgery?