Is prior bariatric surgery associated with poor COVID-19 outcomes? A systematic review and meta-analysis of case-control studies.

Background: Obesity is an independent risk factor for severe coronavirus disease 2019 (COVID-19), but there is little evidence on whether prior bariatric surgery benefits the outcomes of patients with COVID-19. We aimed to summarize this relationship by conducting a systematic review and meta-analysis of current case-control studies. Methods: We searched several electronic databases for case-control studies conducted between January 2020 and March 2022. We compared the rates of mortality, mechanical ventilation, intensive care unit (ICU) admission, dialysis, hospitalization, and length of hospital stay between COVID-19 patients with and without a history of bariatric surgery. Results: We included six studies with 137 903 patients; 5270 (3.8%) had prior bariatric surgery, while 132 633 (96.2%) did not. COVID-19 patients with a history of bariatric surgery had significantly lower mortality (odds ratio (OR) = 0.42; 95% confidence interval (CI) = 0.23-0.74), ICU admission (OR = 0.48; 95% CI = 0.36-0.65), and mechanical ventilation rates than those with a history of non-bariatric surgery (OR = 0.51; 95% CI = 0.35-0.75). Conclusions: Prior bariatric surgery was associated with a reduced risk of mortality and reduced severity of COVID-19 in patients with obesity compared to those with no prior bariatric surgery. Further large-sample prospective studies are needed to support these results. Registration: CRD42022323745.