Association of bariatric surgery with indicated and unintended outcomes: An umbrella review and meta‐analysis for risk–benefit assessment

Bariatric surgery can cause numerous functional changes to recipients, some of which are unintended. However, a systematic evaluation of wide-angled health benefits and risks following bariatric surgery has not been conducted. We systematically evaluated published systematic reviews of randomized controlled trials and observational studies reporting the association between bariatric surgery and health outcomes. We performed subgroup analyses by surgery type and sensitivity analysis, excluding gastric band. Thirty systematic reviews and 82 meta-analyzed health outcomes were included in this review. A total of 66 (80%) health outcomes were significantly associated with bariatric surgery, of which 10 were adverse outcomes, including suicide, fracture, gastroesophageal reflux after sleeve gastrectomy, and neonatal morbidities. The other 56 outcomes were health benefits including new-onset diabetes mellitus (DM) (odds ratio [OR] = 0.39; 95% confidence interval [CI] = 0.19-0.79), hypertension (OR = 0.36; 95% CI = 0.33-0.40), dyslipidemia (OR = 0.33; 95% CI = 0.14-0.81), cancers (OR = 0.65; 95% CI = 0.53-0.80), cardiovascular diseases (CVDs), and women's health. Surgery is associated with reductions in all-cause mortality and death due to cancer, DM, and CVD. Bariatric surgery has both beneficial and harmful effects on a broader than expected array of patients' health outcomes. An expansion of the indication for bariatric surgery could be discussed to include a broader population with metabolic vulnerabilities.