Navigating uncharted territory in surgical innovation: systematic review of non-standard metabolic bariatric surgery procedures

BACKGROUND: Surgical innovation often outpaces robust evaluation. This study used metabolic bariatric surgery (MBS), a field of high-intensity innovation, as a case study to evaluate reporting standards and ethical oversight for experimental procedures within surgery. METHODS: A systematic review was conducted in accordance with PRISMA 2020 guidelines. PubMed/MEDLINE, the Web of Science, Scopus, the Cochrane Library, and Embase were searched from January 2000 to December 2024 using terms related to MBS, surgical innovation, and non-standard intestinal bypass procedures. Original studies reporting first-in-human or early clinical series of non-standard primary MBS involving significant intestinal modification were included and reviews, editorials, conference abstracts, revisional surgery, purely restrictive procedures, and device-based interventions were excluded. Two reviewers independently screened studies, extracted data on publication timing, patient numbers, follow-up, ethical approval, and trial registration, and assessed risk of bias using the Newcastle-Ottawa scale (NOS), the Joanna Briggs Institute critical appraisal checklist, and the ROBINS-I tool. RESULTS: From 57 included studies (10 754 patients), the median time from first human operation to publication was 5 (interquartile range 3-8) years. The median initial cohort size was 39 (range 1-1074) patients. Institutional Review Board or ethics committee approval was reported in 47 of 57 studies (82%), while prospective clinical trial registration was documented in only 6 of 57 studies (11%). Methodological quality was low (mean NOS score of 5.0 out of 9), with 56 of 57 studies judged at high risk of bias. Out of 57 studies, only 15 (26%) reported outcomes at ≥3 years and only 8 (14%) reported outcomes at ≥5 years. CONCLUSION: This MBS case study reveals delayed publication and a widespread lack of prospective trial registration, exposing over 10 000 patients to experimental procedures outside a transparent research framework. These findings highlight a systemic failure in surgical innovation governance and underscore an urgent need for a cultural shift towards mandatory, prospective oversight frameworks to ensure patient safety and credible evidence generation.