Diabetes, Hypertension, Body Mass Index, Smoking and COVID-19-Related Mortality: A Systematic Review and Meta-Analysis of Observational Studies

Abstract

Background: Patients who smoke and with preexisting comorbidities have a greater risk of developing severe coronavirus disease 2019 (COVID-19) and have a higher mortality rate. However, the number of deaths attributable to diabetes, hypertension, obesity, or smoking have never been estimated. We conducted a systematic literature review and meta-analysis of observational studies to investigate the association between diabetes, hypertension, body mass index (BMI) or smoking with the risk of death in patients with COVID-19.Methods: Relevant observational studies were identified by searches in the PubMed and Embase databases through October 29, 2020. Random-effects models were used to estimate summary relative risks (SRRs) and 95% confidence intervals (CIs). We further estimated the proportion of deaths attributable to these conditions. Certainty of evidence was assessed using the Cochrane methods and the GRADE framework. This study is registered with PROSPERO, CRD42020218115.Findings: A total of 186 studies representing 210,447 deaths among 1,304,587 patients with COVID-19 were included in this analysis. The SRR for death in COVID-19 patients was 1.54 (95% CI=1.44-1.64, I2=92%, n=145, low certainty) for diabetes and 1.42 (95% CI=1.30-1.54, I2=90%, n=127, low certainty) for hypertension compared to patients without each of these comorbidities. Regarding obesity, the SSR was 1.45 (95% CI=1.31-1.61, I2=91%, n=54, high certainty) for patients with BMI ≥30kg/m2 compared to those with BMI Interpretation: Our findings suggest that diabetes, hypertension, obesity and smoking are major contributors to COVID-19 mortality accounting for nearly 30% of COVID-19 deaths.Funding Statement: There was no funding source for this study.Declaration of Interests: We declare no competing interests.