Kaiser Permanente researchers led largest long-term national study of bariatric surgery, comparing the 3 most common operations — among first results from PCORnet®
SEATTLE — Adults with severe obesity had greater initial and sustained weight loss with gastric bypass surgery than either sleeve gastrectomy or adjustable gastric banding, according to a new published today in the Annals of Internal Medicine.
This is the largest long-term study of bariatric surgery to date. It included more than 46,000 patients at 41 participating health systems in 11 Clinical Data Research Networks nationwide, thanks to its use of a large new resource called PCORnet®, the National Patient-Centered Clinical Research Network.
Bariatric surgeons can use various operations to help people lose weight by making changes to their digestive system. This study did a head-to-head comparison of 1-, 3- and 5-year results from the three most commonly performed weight-loss operations: gastric bypass, sleeve gastrectomy and adjustable gastric banding.
The findings are important because severe obesity — a body mass index (or BMI) of at least 35 kg/m 2 — affects more than 15 percent of U.S. adults, according to the National Health and Nutrition Examination Survey. National Institutes of Health guidelines consider people with a BMI of 40 kg/m 2, or at least 35 kg/m 2 for people with diabetes or other obesity-related diseases, eligible for bariatric surgery.
“Bariatric surgery is widely considered the most effective way to treat severe obesity and induce long-term weight loss,” said first author David Arterburn, MD, MPH, an internist and senior investigator at Kaiser Permanente Washington Health Research Institute. “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:
“These findings give strong evidence that bypass and sleeve are effective for lasting weight loss for adults with severe obesity,” said Kathleen M. McTigue, MD, MPH, MS, another study leader and an associate professor of medicine and epidemiology at the University of Pittsburgh. “We hope this helps people to make more informed decisions about their care, as they talk with their health care providers about the respective benefits and risks of the most common weight-loss procedures.”
Members of the same PCORnet® Bariatric Study Collaborative team had found similar results in teenagers.
Because of the large sample size, the researchers could examine subgroups of people to assess whether certain characteristics improved or worsened their chance of weight loss success. They found that men, African Americans, Hispanics, people age 65 and older, and people with diabetes or lower BMIs (less than 50) tended to lose less weight than did other people in the study. But these differences between patient groups were small — less than 3% differences in weight lost at 1, 3 and 5 years across groups — which was much less than the differences between the procedures. For instance, the difference between weight lost with gastric bypass and sleeve gastrectomy was 6% at 1 year and 7 percent at 5 years.
The 30-day risk of major adverse events, such as a prolonged hospitalization or another operation, were generally low across all three procedures. Sleeve gastrectomy had the lowest rate of major adverse events (2.6%), followed by gastric banding (2.9%), and then gastric bypass (5.0%).
The new results are among the first to be produced using the resources of PCORnet®, an innovative initiative funded by the Patient-Centered Outcomes Research Institute (or PCORI). PCORnet® is designed to produce clinical insights faster and less expensively than traditional clinical studies. It involves multiple individual networks that together represent more than 100 million patients.
The network securely collects health information during routine care — not including data that could help identify individuals — to produce real-world evidence with outcomes that matter to patients, who are full partners in this research.
“Our patients and providers were critical to the success of this study,” said Karen J. Coleman, PhD, MS, another study leader and a research scientist at Kaiser Permanente in Southern California’s Department of Research & Evaluation in Pasadena. “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.”
“We helped the group think through the most important questions for patients, like risks and safety concerns,” said the Rev. Neely Williams, MDiv, a patient-principal investigator on the study and the CEO of the Community Partners’ Network in Nashville. “We also explored how best to share evidence with patients.”
The PCORnet® Bariatric Study Collaborative team is continuing to examine the outcomes of different types of weight-loss surgery for longer-term safety as well as outcomes in people with diabetes.
This PCORnet® study, registered at ClinicalTrials.gov (NCT02741674), was funded by PCORI through PCORI Award OBS-1505-30683.
For the PCORnet® Bariatric Study Collaborative, the other coauthors are Robert Wellman, MS, R. Yates Coley, PhD, Andrea J. Cook, PhD, Jane Anau, and Roy Pardee, JD, MA, of Kaiser Permanente Washington Health Research Institute; Sameer Murali, MD, of Kaiser Permanente in Southern California’s Department of Research and Evaluation in Pasadena; Sengwee Toh, ScD, Jessica Sturtevant, MS, and Casie Horgan, MPH, of Harvard Medical School’s Department of Population Medicine and Harvard Pilgrim Health Care Institute in Boston; Ana Emiliano, M.D., of Rockefeller University in New York; Steven R. Smith, MD, of Florida Hospital’s The Translational Research Institute for Metabolism and Diabetes in Orlando; Andrew O. Odegaard, PhD, MPH, of the University of California, Irvine School of Medicine’s Department of Epidemiology; Cheri Janning RN, BSN, MS, of Duke Clinical & Translational Science Institute in Durham, NC; Anita Courcoulas, MD, MPH, of the University of Pittsburgh’s Department of Surgery.
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