Impact of body mass index on the outcome of Japanese patients with cardiovascular diseases and/or risk factors hospitalized with COVID-19 infection

Background: Obesity is reported to be a predictor of adverse clinical events in coronavirus disease 2019 (COVID-19) in Western countries. However, there are limited data reported regarding the prognostic impact of obesity in Asian patients. We investigated the relationship between body mass index (BMI) and in-hospital outcomes in 580 Japanese patients with cardiovascular disease and/or risk factors and who were admitted for COVID-19 infection using data from 49 hospitals in Japan. Methods: We analyzed data from the Clinical Outcomes of COVID-19 Infection in Hospitalized Patients with Cardiovascular Disease and/or Risk Factors (CLAVIS-COVID) registry. BMI was classified into four groups accordance with the definition of the Japan Society for the Study of Obesity, as follows: underweight, <18.5 kg/m²; normal range, 18.5 to <25 kg/m²; pre-obese, 25 to 30 kg/m²; and obese, ≥30 kg/m². Results: In-hospital death occurred in 15.0% (n=87) of the patients and intubation was performed for 139 (24.0%) patients. In a multivariate analysis, we found a significant association between higher BMI and in-hospital mortality [underweight: hazard ratio (HR) 0.47, 95% confidence interval (CI) 0.23-0.97; p=0.041; pre-obese: HR 1.46, 95%CI 0.84-2.55; p=0.18; and obese: HR 3.28, 95%CI 1.34-8.02; p=0.009 vs. normal range]. In contrast, the association between BMI and the intubation rate was not statistically significant. Conclusions: Obesity was associated with a stepwise increase in the risk of in-hospital mortality in Japanese patients with COVID-19 infection. The threshold BMI for the increased risk of a worse outcome was 30, which was much lower in comparison to Western countries.