The clinical evidence base demonstrating bariatric surgery’s health benefits is much larger than it was when the NIH last held a Consensus Panel in 1991. Still, it remains unclear whether ongoing studies will address critical questions about long-term complication rates and the sustainability of weight loss and comorbidity control.
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the National Heart, Lung, and Blood Institute (NHLBI) convened a multidisciplinary workshop in May 2013 to summarize the current state of knowledge of bariatric surgery, review research findings on the long-term outcomes of bariatric surgery, and establish priorities for future research directions.
The evidence presented at the workshop was selected by the planning committee for both its quality and duration of follow up. The data review emphasized RCTs and large observational studies with long-term follow up, with or without a control group.
Several small RCTs showed greater weight loss and T2DM remission compared to non-surgical treatments within the first 2 years of follow-up after bariatric surgery. Large, long-term observational studies show durable (>5 years) weight loss, diabetes and lipid improvements with bariatric surgery. Still unclear are predictors of outcomes, long-term complications, long-term survival, micro- and macro-vascular events, mental health outcomes, and costs. The studies needed to address these knowledge gaps would be expensive and logistically difficult to perform.
High-quality evidence shows that bariatric surgical procedures result in greater weight loss than non-surgical treatments and are more effective at inducing initial T2DM remission in obese patients. More information is needed about the long term durability of comorbidity control and complications after bariatric procedures and this evidence will most likely come from carefully designed observational studies.