Severe Obesity: Bariatric Surgery vs. Life-Style-Intervention

Severe Obesity: Bariatric Surgery vs. Life-Style-Intervention Wurzburg Adipositas Study - WAS

The purpose of this study is to investigate the effects of weight loss induced by gastric bypass surgery in comparison to a psychotherapy-enhanced lifestyle intervention on cardiopulmonary performance and quality of life in patients with morbid obesity.

Obesity is a rapidly emerging health problem and an established risk factor for cardiovascular diseases. Bariatric surgery profoundly reduces body weight and mitigates sequelae of obesity. Especially randomized trials comparing the effects of bariatric surgery to conservative treatment in concerns of cardiac function are still lacking.

The randomized WAS trial compares the effects of Roux-en-Y gastric bypass (RYGB) versus psychotherapy-supported lifestyle modification in morbidly obese patients. The co-primary endpoint addresses 1-year changes in cardiovascular function (peak VO2 during cardiopulmonary exercise testing) and quality of life (Short-Form-36 physical functioning scale). Prior to randomization, all included patients underwent a multimodal anti-obesity treatment for 6-12 months. Thereafter, patients were randomized and followed through month 12 to collect primary endpoints. Afterwards, patients in the lifestyle group could opt for surgery, and final visit was scheduled for all patients 24 months after randomization.

The study was initially designed in 2008 as part of several interdisciplinary studies for a targeted grant and received a positive vote from the responsible ethics committee.

Prior the actual start of the study in July 2011, the initial study protocol and the patient informed consent were updated and further specified. This amendment was submitted to the Ethics Committee on June 9, 2011, with a positive vote on June 30, 2011 (Amendment 1).

An Amendment 2 was submitted to Ethics Committee on 08.10.2014 (positive vote 16.12.2014) to adjust randomization (previously 1:1 to the two study arms) for an unequal drop-out rate in the two study arms with higher rate in the intensified lifestyle modification. In addition, few secondary endpoints were adapted and the role of the principal investigator changed from Prof. Stefan Frantz to Prof. Martin Fassnacht.

Inclusion Criteria:

• Age ≥18 years
• BMI >40 kg/m2 or BMI >35 kg/m2 with severe comorbidities
• Indication for Roux-en-Y gastric bypass surgery
• Ability to perform cardiopulmonary exercise testing (CPET)
• Written informed consent

Exclusion Criteria:

• Pregnancy or breast feeding
• Unstable angina pectoris
• Life expectancy <12 months
• Endocrine or psychiatric disorder as cause of obesity
• Systemic glucocorticoid treatment (with exception of glucocorticoid replacement therapy)
• Abuse of drugs or alcohol within the last 5 years
• Inability to attend regular study visits for logistic reasons
• Participation in competing trials