Diverse approaches to the health economic evaluation of bariatric surgery: a comprehensive systematic review

BACKGROUND: Health economic evaluations inform healthcare resource allocation decisions for treatment options for obesity including bariatric/metabolic surgery. As an important advance on existing systematic reviews, we aimed to capture, summarize and synthesize a diverse range of economic evaluations on bariatric surgery. METHODS: Studies were identified by electronic screening of all major biomedical/economic databases. Studies included if they reported any quantified health economic cost and/or consequence with a measure of effect for any type of bariatric surgery from 1995 to September 2015. Study screening, data extraction and synthesis followed international guidelines for systematic reviews. RESULTS: Six thousand one hundred eighty-seven studies were initially identified. After two levels of screening, 77 studies representing 17 countries (56% USA) were included. Despite study heterogeneity, common themes emerged, and important gaps were identified. Most studies adopted the healthcare system/third-party payer perspective; reported costs were generally healthcare resource use (inpatient/shorter-term outpatient). Out-of-pocket costs to individuals, family members (travel time, caregiving) and indirect costs due to lost productivity were largely ignored. Costs due to reoperations/complications were not included in one-third of studies. Body-contouring surgery included in only 14%. One study evaluated long-term waitlisted patients. Surgery was cost-effective/cost-saving for severely obese with type 2 diabetes mellitus. Study quality was inconsistent. DISCUSSION: There is a need for studies that assume a broader societal perspective (including out-of-pocket costs, costs to family and productivity losses) and longer-term costs (capture reoperations/complications, waiting, body contouring), and consequences (health-related quality-of-life). Full economic evaluation underpinned by reporting standards should inform prioritization of patients (e.g. type 2 diabetes mellitus with body mass index 30 to 34.9 kg/m(2) or long-term waitlisted) for surgery.