Bariatric Surgery

Over the course of the workshop, participants reviewed and discussed the rationale for future trials of bariatric surgery. The members considered specific populations, intervention and control conditions, and clinical outcomes for inclusion in future clinical trials. Additionally, feasibility issues for conducting clinical trials of surgical interventions were reviewed.

Workshop participants concurred with the need for randomized controlled trials as an important next step in developing a strong evidence base for bariatric surgery. To maximize the potential knowledge gain, an observational arm was considered an essential portion of any future clinical trial. This observational arm would enroll those patients who initially express interest in the trial but ultimately had a strong preference for either surgery or medical therapy. Use of this type of patient preference study design was felt to provide an efficient method of advancing the science of bariatric surgery.

A priority population for clinical trials in bariatric surgery is patients at high risk for cardiovascular disease, defined by age, co-morbidities, and pre-existing cardiovascular disease. Within this priority group, important sub-populations to include are patients with sleep disordered breathing, patients with asthma or related breathing disorders, and patients with heart failure including right sided heart failure and preserved systolic function heart failure. Preserved systolic function heart failure patients were considered an important group for initial focus. Small observation studies have demonstrated improvement in heart function after bariatric surgery. Given the high prevalence of obesity among preserved systolic function heart failure patients and the current limited treatment options, a trial in this population may provide significant benefit.

The members also felt strongly that future trials should include patients with a body mass index (BMI) as low as 30 kg/m2. Many patients at high risk for cardiovascular disease have a BMI between 30 and 35 kg/m2. Although not currently recommended, bariatric surgery has theoretical benefit for patients in this weight range.

No consensus was reached on the type of bariatric surgery to be tested (gastric banding versus gastric bypass). Although gastric banding is less invasive and more easily reversible, weight loss is slower and dependent on both the protocol used for band inflation and the adherence of the patients to those adjustments. Standardization of either surgical procedure to maintain the fidelity of the intervention was raised as an important consideration but may be easier to accomplish with gastric bypass. The optimal comparison group was felt to be a combination of intensive lifestyle treatment that included diet and exercise, and optimal medical care of all co-morbidities. Ideally, trial outcomes would be clinical: all-cause mortality, cardiovascular mortality, non-fatal myocardial infarction, and non-fatal stroke. Other outcomes felt to be of significant importance were patient satisfaction, quality of life, healthcare utilization, surgical complications, and patient preference elicitation. Shorter length trials should focus on recognized surrogate or intermediate markers such as changes in cardiac morphology and function as measured on magnetic resonance imaging or echocardiography, atherosclerotic burden as measured by carotid intima-media thickness, exercise capacity as measured by such as V02 max, and sleep disordered breathing as measured by the apnea-hypopnea index.

Finally, the working group felt that support from private health care providers and Medicare would facilitate these studies. Centers from other countries may also be approached. These future trials should be multi-disciplinary and include investigators with expertise in surgery, cardiovascular disease, sleep disordered breathing, and clinical trials, among others. Additionally, the working group members encouraged continued collaborative efforts between interested institutes at National Institute of Health (NIH) and investigators to advance the science of bariatric surgery.

Publication Plans

A full report is in preparation.

Co-Chairs

• David Flum, MD, University of Washington, Seattle, WA
• Eric Velazquez, MD, Duke University, Durham, NC al Center

Panel Members

• Steven Belle, PhD, University of Pittsburgh, Pittsburgh, PA
• Anita Courcoulas, MD, University of Pittsburgh, Pittsburgh, PA
• David Cummings, MD, University of Washington, Veterans Affairs Puget Sound Health Care System, Seattle WA
• Rosemarie Hakim, PhD, Centers for Medicare and Medicaid Services (CMS), Baltimore MD
• Frank LeFevre, MD, Northwestern University, Chicago, IL
• Richard Millman, MD, Alpert Medical School of Brown University, Providence, RI
• James Mitchell, MD, Neuropsychiatric Research Institute, Fargo, ND
• Michael Parides, PhD, Mount Sinai School of Medicine, New York , NY
• Sanjay Patel, MD, Brigham and Women’s Hospital, Boston, MA
• Ileana Pina, MD, Case Western Reserve University, Cleveland, OH
• Xavier Pi-Sunyer, MD, St. Lukes/Roosevelt Hospital Center, New York, NY
• Paul Poirier, MD, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, CA
• Bruce Wolfe, MD, Oregon Health and Science University, Portland OR

NIH Staff

• Denise Bonds, MD, Division of Cardiovascular Sciences, NHLBI
• Myrlene Staten, MD, Division Diabetes, Endocrinology and Metabolic Diseases, NIDDK
• Mary Horlick, MD, Division Digestive Diseases and Nutrition, NIDDK
• Susan Yanovski, MD, Division Digestive Diseases and Nutrition, NIDDK

Last Updated: June 2011