Association of body mass index (BMI) with critical COVID-19 and in-hospital mortality: A dose-response meta-analysis

Abstract

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 ≥ 30 kg/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 <30 kg/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(P_{non-linearity} = 0.242) and mortality (P_{non-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 ≥ 30 kg/m²) was associated with a significantly increased risk of critical COVID-19 and in-hospital mortality of COVID-19.

Keywords: BMI; Body mass index; COVID-19; Meta-analysis; Obesity.

Fig. 1

Flowchart of the study procedure.

Fig. 2

Effects of BMI > 30 kg/m² vs. BMI < 30 kg/m² on COVID-19 severity.

Fig. 3

Meta-analysis based on the adjusted effect estimates to explore the effect of BMI > 30 kg/m² vs. BMI < 30 kg/m² on COVID-19 severity.

Fig. 4

Effects of BMI > 30 kg/m² vs. BMI < 30 kg/m² on COVID-19 mortality.

Fig. 5

Meta-analysis based on the adjusted effect estimates to explore the effect of BMI > 30 kg/m² vs. BMI < 30 kg/m² on COVID-19 mortality.

Fig. 6

Random-effects meta-regression analysis to explore the effect of age on association between BMI > 30 kg/m² and COVID-19 severity (a) and mortality (b).

Fig. 7

Random-effects linear dose-response meta-analysis of the association between BMI and the risk of severe COVID-19(P_{non-linearity} = 0.242). Solid line and long dashed lines represent odds ratio and its 95% confidence interval.

Fig. 8

Random-effects linear dose-response meta-analysis of the association between BMI and COVID-19 mortality (P_{non-linearity} = 0.116). Solid line and long dashed lines represent odds ratio and its 95% confidence interval.