Clinical, Economic, and System-Level Outcomes of Bariatric Surgery in Adults: Protocol for a Systematic Review

Obesity affects approximately 880 million adults worldwide and carries substantial health, economic, and social consequences. Although bariatric surgery achieves sustained weight loss and metabolic improvement, existing systematic reviews largely predate 2020 and rarely integrate clinical, economic, and system-level perspectives within a single synthesis.

This study aims to identify, critically appraise, and synthesize evidence published between 2020 and 2025 on the clinical effectiveness and economic impact of bariatric surgery in adults with obesity. A secondary, exploratory objective is to address system-level resource utilization, specifically length of stay, preoperative pathway duration, and outpatient care burden.

This protocol follows the PRISMA-P (Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols) 2015 guidance and is registered with the International Prospective Register of Systematic Reviews (PROSPERO: CRD420261351022). Eligible studies will enroll adults aged 18 years or older with obesity (BMI ≥30 kg/m²) undergoing any primary bariatric procedure, including Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG), one-anastomosis gastric bypass (OAGB), adjustable gastric banding (LAGB), and biliopancreatic diversion with or without duodenal switch (BPD±DS); revisional procedures are excluded as the index intervention. Eligible designs include randomized controlled trials, cohort, case-control, cross-sectional, and economic evaluation studies published in English. MEDLINE (via PubMed), Embase, Scopus, and Web of Science will be searched using predefined, database-tailored strategies; records will be managed in Zotero (Corporation for Digital Scholarship). A single primary reviewer will perform screening, extraction, and risk-of-bias (RoB) assessment, with at least 20% independently duplicated by a second reviewer, weighted toward full-text and included studies. RoB will be assessed with RoB 2 and ROBINS-I (Risk of Bias in Nonrandomized Studies of Interventions); economic evaluations will be appraised for completeness of reporting with the CHEERS (Consolidated Health Economic Evaluation Reporting Standards) 2022 statement and for methodological quality with the CHEC (Consensus on Health Economic Criteria) checklist. The primary synthesis will be narrative; meta-analysis will be considered only where prespecified comparability criteria are met. Certainty of evidence will be rated using GRADE (Grading of Recommendations Assessment, Development, and Evaluation).

This protocol describes a review that is currently in progress. Registration with PROSPERO was completed on April 15, 2026, and database searches were run on August 1, 2026, identifying 9400 records. Title-and-abstract screening is scheduled to begin on August 15, 2026. Data extraction and synthesis are expected to be completed by the end of 2026, with publication of the completed review anticipated in the first half of 2027.

This protocol provides a transparent and reproducible methodology for an integrated, contemporary synthesis of the clinical, economic, and system-level outcomes of bariatric surgery in adults. The findings are intended to inform health policy, resource planning, and future research priorities.