PCORnet Blog

Weighing the Options: PCORnet Study Shows Gastric Bypass Surgery Yields Greater Weight Loss than Other Procedures

PCORnet, the National Patient-Centered Clinical Research Network, is delivering on its mission to answer important questions that help patients make better-informed health care decisions. The Annals of Internal Medicine this week published findings from the PCORnet Bariatric Study.


This study compared the health benefits of three common weight-loss operations: gastric bypass, sleeve gastrectomy, and adjustable gastric banding. Researchers found that adults with severe obesity had greater initial and sustained weight loss with gastric bypass surgery (71 pounds on average five years post-surgery) than with sleeve gastrectomy (52 pounds on average) or adjustable gastric banding (33 pounds on average).


Rates of major problems occurring within 30 days of surgery were small for all three procedures, though highest for bypass.


With data from more than 46,000 patients across 41 health systems accessed through PCORnet, the study is the largest long-term study of bariatric surgery to date.


Although the ultimate choice of weight loss surgery has many variables for patients and their doctors to consider, the study’s head-to-head comparison of 1-, 3-, and 5-year results from the three most commonly performed weight-loss operations sheds much needed light on an important aspect of what to expect from weight loss procedures.


“Bariatric surgery is widely considered the most effective way to treat severe obesity and induce long-term weight loss,” David Arterburn, MD, MPH, an internist and senior investigator at Kaiser Permanente Washington Health Research Institute, who served as a co-principal investigator of the study, said in a news release. “We wondered about sleeve gastrectomy, which has quickly become the most commonly performed bariatric procedure in the United States. Because it’s the newest—introduced less than a decade ago—less evidence has been available to compare it against the longstanding gastric bypass and adjustable gastric band.”


The investigators found that:

  • People who had gastric bypass surgery had lost 31 percent of their weight at the first year and maintained 26 percent of their loss at 5 years.
  • People who had sleeve gastrectomy had lost 25 percent of their pre-surgery body weight at 1 year and maintained 19 percent weight loss at 5 years.
  • That translates into a 19-pound difference in weight loss between gastric bypass and sleeve gastrectomy at 5 years for the average person in this study who weighed 277 pounds before surgery.
  • By contrast, adjustable gastric banding was much less effective for losing weight and keeping it off, with 14 percent and 12 percent of weight lost at 1 and 5 years, respectively.

The new results showcase the power of PCORnet to deliver on its goal to produce faster, less costly, and more meaningful research results than traditional clinical trials. By working with PCORnet’s partner networks, which collectively represent more than 100 million patients, researchers were able to securely assess de-identified health information collected during routine care to compare each weight loss procedure. As with all PCORnet studies, patients played a central role as partners in the research process.


“Our patients and providers were critical to the success of this study,” Karen J. Coleman, PhD, a research scientist at Kaiser Permanente in Southern California’s Department of Research and Evaluation in Pasadena and co-author of the study, noted in the news release. “They helped us craft the question, pick the variables to study, interpret the findings, and present the results. We could never have done such a comprehensive study without their partnership.”


Are you interested and want to learn more?

  • Arterburn and patient co-investigator Neely Williams discuss the implications of this study in this blog post.
  • Study co-principal investigator Kathleen McTigue, MD, MPH, Associate Professor of Medicine, Epidemiology, and Clinical/Translational Science at the University of Pittsburgh, will discuss the results at the 4th PCORI Annual Meeting taking place October 31-November 2 in Washington, DC. In-person attendance at sessions is free and the session will be available via live webcast 1:30 to 3 pm ET Thursday, November 1.
  • In addition, Arterburn will present details on the results at Obesity Week, taking place November 11-15 in Nashville, Tennessee. There is still time to register.