Association of Body mass index (BMI) with Critical COVID-19 and in-hospital Mortality: a dose-response meta-analysis

Background and Purpose The coronavirus disease 2019 (COVID-19) pandemic presents an unprecedented health crisis to the entire world. As reported, the body mass index (BMI) may play an important role in COVID-19; however, this still remains unclear. The aim of this study was to explore the association between BMI and COVID-19 severity and mortality. Methods The Medline, PubMed, Embase and Web of science were systematically searched until August 2020. Random-effects models and dose-response meta-analysis were used to synthesize the results. Combined odds ratios (ORs) with their 95% confidence intervals (CIs) were calculated, and the effect of covariates were analyzed using subgroup analysis and meta-regression analyses. Results A total of 16 observational studies involving 109,881 patients with COVID-19 were included in the meta-analysis. The pooled results showed that patients with a BMI≥30kg/m2 had a 2.35-fold risk(OR = 2.35, 95%CI = 1.64 − 3.38, P < 0.001) for critical COVID-19 and a 2.68-fold risk for COVID-19 mortality (OR = 2.68, 95%CI = 1.65 −4.37, P < 0.001 ) compared with patients with a BMI <30kg/m2. Subgroup analysis results showed that patients with obesity and age > 60 years was associated with a significantly increased risk of critical COVID-19(OR = 3.11, 95%CI = 1.73 − 5.61, P < 0.001) and COVID-19 mortality(OR = 3.93, 95%CI = 2.18 − 7.09, P < 0.001). Meta-regression analysis results also showed that age had a significant influence on the association between BMI and COVID-19 mortality(Coef.=0.036, p=0.048). Random-effects dose-response meta-analysis showed a linear association between BMI and both critical COVID-19(Pnon-linearity = 0.242) and mortality (Pnon-linearity = 0.116). The risk of critical COVID-19 and mortality increased by 9%(OR = 1.09, 95%CI = 1.04 −1.14, P < 0.001) and 6%(OR = 1.06, 95%CI = 1.02 −1.10, P = 0.002) for each 1 kg/m2 increase in BMI, respectively. Conclusions Evidence from this meta-analysis suggested that a linear dose-response association between BMI and both COVID-19 severity and mortality. Further, obesity(BMI≥30kg/m2) was associated with a significantly increased risk of critical COVID-19 and in-hospital mortality of COVID-19.