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First Major Bariatric Surgery Study Finds Low Risk

In the first federally funded, multicenter clinical study to evaluate the overall risks, benefits and long-term impact of bariatric surgery, researchers have found the overall risk of death and other adverse outcomes is low and varies considerably from patient to patient. Their findings will be published in the July 30 issue of The New England Journal of Medicine.

The large-scale study was conducted by LABS (Longitudinal Assessment of Bariatric Surgery), a National Institutes of Health-funded consortium comprising six grants nationwide, including Oregon Health & Science University. Legacy Good Samaritan Hospital is one of 10 clinical sites participating in the LABS-1 trial.

The LABS consortium was convened by the National Institute of Diabetes and Digestive and Kidney Diseases to determine the frequency of adverse outcomes, and the factors associated with them, to help doctors and patients better evaluate treatment for extreme obesity. “Prior to LABS, the risks and benefits for bariatric surgery had not been thoroughly assessed using multicenter, rigorous methodology,” explained Bruce Wolfe, M.D., co-author and chairman of the LABS consortium Steering Committee and a professor of surgery at Oregon Health & Science University.

In the study, researchers followed 4,776 first-time bariatric surgery patients for 30 days. Gastric bypass surgery (Roux-en-Y) was performed in 3,412 patients, laparoscopic adjustable gastric banding was performed in 1,198 patients, and 166 patients underwent other procedures that were not included in the final analysis.

At 30 days post-surgery, the researchers found the death rate among patients who underwent a Roux-en-Y gastric bypass or laparoscopic adjustable gastric banding was .3 percent, and a total of 4.3 percent of patients had at least one major adverse outcome, including death, venous thromboembolism, the need for surgical, endoscopic or percutaneous intervention, or failure to be discharged from the hospital.

“We found certain conditions such as a history of deep-vein thrombosis or a diagnosis of obstructive sleep apnea were associated with an increased risk of adverse outcomes, and that extreme obesity significantly impacted the risk,” said Wolfe. “We recommend doctors counsel patients about short-term safety as well as the long-term effects and inherent risks associated with being extremely obese when considering bariatric surgery. This information should help doctors and patients make appropriate choices.”

LABS research is ongoing. Enrollment in LABS II is complete, and future reports will address the balance of risks and benefits for patients.

The LABS (Longitudinal Assessment of Bariatric Surgery) consortium includes six academic bariatric centers, 11 hospitals, 31 surgeons and nearly 5,000 patients. It comprises experts in bariatric surgery, obesity research, internal medicine, endocrinology, behavioral science, outcomes research, epidemiology, and other relevant fields. For more information about LABS, visit

For a description of Roux-en-Y bariatric surgery and laparoscopic gastric banding, visit

Oregon Health & Science University is the state's only health and research university and Oregon's only academic health center. OHSU is Portland's largest employer and the fourth largest in Oregon (excluding government). OHSU's size contributes to its ability to provide many services and community support activities not found anywhere else in the state. It serves patients from every corner of the state, and is a conduit for learning for more than 3,400 students and trainees. OHSU is the source of more than 200 community outreach programs that bring health and education services to every county in the state.

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