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Introduction
Obesity is one of the greatest public health problems in industrialised countries. 1 2 In the US, UK, and Australia, for instance, the prevalence of obesity (body mass index (weight (kg)/(height (m)2) >30) has more than doubled in the past 25 years. 2 Currently, 67% of the US population is either overweight or obese, and in most European countries the prevalence ranges between 40% and 50%. 3 Obesity is associated with an increased risk for type 2 diabetes, hypertension, dyslipidaemia, cardiovascular diseases, musculoskeletal disorders (such as osteoarthritis), certain types of cancer, and mortality. 4 This entails huge healthcare costs due to obesity. 5
Treatment options for obesity include non-surgical treatment and bariatric surgery. The non-surgical treatment is usually a multicomponent approach comprising behavioural therapy, dietary changes with the main aim of reducing energy intake, increasing physical activity, and various pharmacotherapies. 6 The most commonly used bariatric surgery techniques are Roux-en-Y gastric bypass, sleeve gastrectomy, and laparoscopic adjustable gastric banding. 7 8 9 Current guidelines recommend evaluation of bariatric surgery for individuals with a body mass index >40 or >35 with serious comorbidities related to obesity. 8 10 A Cochrane review from 2009 suggested greater body weight loss, improvement in the control of comorbidities, and better quality of life in obese patients who underwent bariatric surgery compared with non-surgical treatment for obesity. 11 However, the review included only a qualitative summary of three randomised controlled trials. 11 12 Since then several further randomised controlled trials have been completed. The present systematic review and meta-analysis aims at comprehensively summarising and quantifying the effects of bariatric surgery compared with non-surgical treatment in randomised controlled trials on weight loss, cardiovascular risk factors, adverse events, and quality of life in individuals with a body mass index >=30.
Methods
Eligibility criteria
Studies were eligible if they were randomised controlled trials (>=6 months' follow-up); included individuals with a body mass index >=30; investigated currently used laparoscopic or open bariatric surgery techniques (Roux-en-Y gastric bypass, adjustable gastric banding, sleeve gastrectomy, biliopancreatic diversion, or biliopancreatic diversion with duodenal switch); investigated as comparator non-surgical treatment for obesity (diet, weight reducing drugs, behavioural therapy, or any combination thereof); and reported changes in body weight; body fat mass; fat-free mass; waist circumference; blood pressure;...