Risk of bias and certainty of evidence on the association between obesity and mortality in patients with SARS-COV-2: An umbrella review of meta-analyses

BACKGROUND & AIMS: This umbrella review of systematic reviews with meta-analysis (SR-MAs) aimed to evaluate the risk of bias and the certainty of the evidence of SR-MAs on the association between obesity and mortality in patients with SARS-CoV-2. METHODS: We conducted a comprehensive literature search until April 22, 2022, in several databases and assessed the risk of bias of SR-MAs according to AMSTAR-2 and the certainty of evidence using the GRADE approach. The degree of overlap between meta-analyses was based on the corrected covered area (CCA) index. The results of each MA [relative risk (RR), hazard ratio (HR), or odds ratio (OR)] were extracted to evaluate the magnitude of the association between obesity and mortality. RESULTS: A total of 24 SR-MAs were eligible, and the association between obesity and mortality was not statistically significant in eight (33.3%) of them, while the OR/HR/RR ranged from 1.14 to 3.52 in the other SR-MAs. The overlap was slight (CCA = 4.82%). The majority of SR-MAs presented critically low quality according to AMSTAR-2 (66.7%), and the certainty of the evidence for most of them (83.4%) was “very low”. CONCLUSIONS: Obesity was associated with an increased risk of death in patients with SARS-CoV-2 infection in most SR-MAs; however, a critical appraisal pointed to a high risk of bias, and the certainty of their evidence was not well graded. The dissemination of poor SR-MAs may limit the interpretation of findings, and we should always aspire to trustworthy scientific evidence. PROSPERO: PROSPERO 2021 CRD42021253142.