The association of prior bariatric surgery (BS) with infection rate and prognosis of coronavirus disease 2019 (COVID-19) remains unclear. We conducted a meta-analysis of observational studies to address this issue.

We searched databases including MEDLINE, Embase, and CENTRAL from inception to May, 2022. The primary outcome was risk of mortality, while secondary outcomes included risk of hospital/intensive care unit (ICU) admission, mechanical ventilation, acute kidney injury (AKI), and infection rate.

Eleven studies involving 151,475 patients were analyzed. Meta-analysis showed lower risks of mortality [odd ratio (OR)= 0.42, 95% CI: 0.27–0.65, p < 0.001, I² = 67%; nine studies; 151,113 patients, certainty of evidence (COE):moderate], hospital admission (OR=0.56, 95% CI: 0.36–0.85, p = 0.007, I² =74.6%; seven studies; 17,810 patients; COE:low), ICU admission (OR=0.5, 95% CI: 0.37–0.67, p < 0.001, I² =0%; six studies; 17,496 patients, COE:moderate), mechanical ventilation (OR=0.52, 95% CI: 0.37–0.72, p < 0.001, I² =57.1%; seven studies; 137,992 patients, COE:moderate) in patients with prior BS (BS group) than those with obesity without surgical treatment (non-BS group). There was no difference in risk of AKI (OR=0.74, 95% CI: 0.41–1.32, p = 0.304, I² =83.6%; four studies; 129,562 patients, COE: very low) and infection rate (OR=1.05, 95% CI: 0.89–1.22, p = 0.572, I² =0%; four studies; 12,633 patients, COE:low) between the two groups. Subgroup analysis from matched cohort studies demonstrated associations of prior BS with lower risks of mortality, ICU admission, mechanical ventilation, and AKI.

Our results showed a correlation between prior BS and less severe COVID-19, which warrants further investigations to verify.