Public Release: 

Tradeoffs found for bypass vs. banding bariatric surgery

Group Health researcher leads SPAN-HMO Research Network study in JAMA Surgery

Group Health Research Institute


IMAGE: Dr. Arterburn is an associate investigator at Group Health Research Institute, a Group Health physician, and an affiliate associate professor of medicine at the University of Washington School of Medicine,... view more

Credit: Group Health Research Institute

SEATTLE--Bypass resulted in much greater weight loss and fewer reoperations than did banding, according to a large national study in JAMA Surgery comparing two of the gastric surgery procedures that are done most commonly for obesity. But bypass was linked to more risk of short-term complications than was banding. The study report is called "Comparative effectiveness of laparoscopic adjustable gastric banding versus laparoscopic gastric bypass in 10 health systems."

"This is important because more and more people are living with severe obesity and having bariatric surgery," said David Arterburn, MD, MPH, an associate investigator at Group Health Research Institute, a Group Health physician, and an affiliate associate professor of medicine at the University of Washington School of Medicine. "They need to know what the potential pros and cons are--so they can have informed discussions with their doctors about which course suits them best, based on what matters most to them as individuals."

The study included nearly 7,500 patients from 10 U.S. health care systems who had laparoscopic bariatric surgery 2005-2009 and were followed up through 2010. The health systems took part in the study through their collaboration in two research networks: the Scalable PArtnering Network for Comparative Effectiveness Research: Across Lifespan, Conditions, and Settings (SPAN) and HMO Research Network.

Patients were more likely to experience at least one major complication within 30 days afterward if they had bypass (3 percent) than if they had banding (1.3 percent). These short-term complications included blood clots in veins, not being discharged from the hospital, and even death.

"But major short-term complications were relatively rare, even with bypass--and they are becoming even less common over time," Dr. Arterburn said.

On average, patients lost nearly 7.0 more body mass index (BMI) points with bypass (14.8) than with banding (8.0). With longer-term follow-up (2.3-6 years), bypass patients were less likely to be operated on again (5.5 percent, versus 13.7 percent for banding patients).

"The optimal bariatric procedure would result in the greatest weight loss and long-term weight loss maintenance with the least risk of short- and long-term problems," Dr. Arterburn added. "Instead, we found tradeoffs between these two common procedures."

Currently, Roux-en-Y gastric bypass accounts for 47 percent--and adjustable gastric banding accounts for 18 percent--of bariatric procedures worldwide. Unlike bypass, banding is reversible--and often reversed, sometimes because of discomfort or failure to lose enough weight. The study didn't include another type of bariatric surgery, called sleeve gastrectomy, which accounts for 28 percent of bariatric procedures. Dr. Arterburn recently discussed in JAMA and The BMJ how well bariatric surgery works.

"We need to compare the longer-term outcomes of various types of this surgery, including maintaining weight loss," Dr. Arterburn said. "Several sites from our group are now looking at the impact of bariatric surgery on the long-term risk of cancer and complications from diabetes."


Grant number 1R01HS019912 from the Agency for Healthcare Research and Quality (AHRQ) supported this research. The sites were Group Health (Washington), Geisinger Health System (Pennsylvania), HealthPartners (Minnesota), Harvard Pilgrim (Massachusetts), Essentia Institute of Rural Health (Minnesota), and Kaiser Permanente regions in Colorado, Georgia, Hawaii, Northern California, and the Northwest (Oregon and Washington).

Dr. Arterburn's coauthors were Sengwee Toh, ScD, of Harvard Medical School and Harvard Pilgrim in Boston; Lisa Herrinton, PhD, and David Fisher, MD, of Kaiser Permanente Northern California in Oakland; Elizabeth A Bayliss, MD, MSPH, and William T. Donahoo, MD, of Kaiser Permanente Colorado and the University of Colorado School of Medicine in Aurora; Jennifer Dickman Portz, PhD, and J. David Powers, MS, of Kaiser Permanente Colorado, in Denver; Sarit Polsky, MD, MSPH, of the University of Colorado School of Medicine; Melissa G. Butler, PharmD, MPH, of Kaiser Permanente Georgia in Atlanta; Rebecca J. Williams, DrPH, MPH, of the University of Hawai'i at Manoa; and V. Vijayadeva, PhD, MBBS, MPH, of Kaiser Permanente Hawai'i in Honolulu.


The Scalable PArtnering Network for Comparative Effectiveness Research: Across Lifespan, Conditions, and Settings (SPAN), funded by the Agency for Healthcare Research and Quality (AHRQ), involves efficient data sharing. SPAN facilitates large-scale comparative effectiveness research--involving multiple organizations, broad populations, and a variety of care delivery systems--about obesity in adults and attention deficit hyperactivity disorder (ADHD) in children. SPAN is developing a distributed research network that is interoperable across a range of health care systems; permits menu-driven querying of data; and utilizes patient-level data for analyses. Distributed research networks are a way to support multi-site comparative effectiveness research, while minimizing the need to transfer patient-level data and to jeopardize patients' privacy and confidentiality. The SPAN Network includes 11 data partners: nine from the existing research network of the HMO Research Network; and two community partners with different delivery systems, data structures, and patient populations.

HMO Research Network

The HMO Research Network includes 18 research centers, each associated with a health care delivery system. Researchers at the centers collaborate on multi-site studies in real-world health care settings across the United States and in Israel. With access to information on more than 15 million ethnically and geographically diverse patients, these researchers are finding solutions for common and rare health problems. Since 1994, the Network has been answering pressing questions about keeping people healthy and delivering effective care.

Group Health Research Institute

Group Health Research Institute does practical research that helps people like you and your family stay healthy. The Institute is the research arm of Seattle-based Group Health Cooperative, a consumer-governed, nonprofit health care system. Founded in 1947, Group Health Cooperative coordinates health care and coverage. Group Health Research Institute changed its name from Group Health Center for Health Studies in 2009. The Institute has conducted nonproprietary public-interest research on preventing, diagnosing, and treating major health problems since 1983. Government and private research grants provide its main funding. Follow Group Health research on Facebook, Twitter, or YouTube.

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