Is BMI Associated with COVID-19 Severity? A Retrospective Observational Study

Background: Coronavirus-19 disease (COVID-19) is an infection with high morbidity and mortality. Obesity and low body mass index (BMI) have both been linked to severe COVID-19, but recent studies have failed to confirm these associations. Objectives: The aim of this study was to examine the relationship between BMI and disease progression in hospitalised patients with COVID-19. Methods: We performed a monocentric, retrospective observational study at the Fondazione Policlinico Gemelli in Rome. We enrolled 1544 (977 men) patients who presented to the emergency department with a positive COVID-19 test between January and December 2021. We divided patients into five classes based on BMI. Demographic, clinical, laboratory, and radiological data were collected for all patients. Results: Of the 1544 patients, 1297 recovered after hospitalization, whereas 247 (16%) died. Of those who died, 16/247 (6.5%) had a BMI below18.5 kg/m², 72/247 (29%) had a BMI between 18.5 and 24.99 kg/m², 103/247 (42%) had a BMI between 25 and 29.99 kg/m², 36/247 (15%) had a BMI between 30 and 35 kg/m², and 20/247 (8%) had a BMI above 35 kg/m². After adjusting the results for age, sex, and concomitant diseases using multivariate logistic regression, we found a significantly increased risk of intensive care unit (ICU) admission in severely obese patients (BMI > 35) compared to normal weight patients (BMI: 18.5-24.99) (p > 0.001). Mortality was not associated with BMI. Conclusion: We confirm that severe obesity is a risk factor for ICU admission in patients with COVID-19. No association was found between BMI and mortality.