Impact of Body Mass Index on COVID-19-Related In-Hospital Outcomes and Mortality

Background: Given the high prevalence of obesity around the globe, patients with coronavirus disease 2019 (COVID-19) are at an increased risk of devastating complications. Methods: A retrospective cohort study was performed to determine the association of basal metabolic index (body mass index (BMI)) with the need for invasive mechanical ventilation (IMV), dialysis, upgrade to an intensive care unit (ICU) and mortality. Independent t-test and multivariate logistic regression analysis were performed to calculate mean differences and adjusted odds ratios (aORs) with its 95% confidence interval (CI), respectively. Results: A total of 176 consecutive patients with confirmed COVID-19 diagnosis were included. The mean age was 62.2 years, with 51% being male patients. The mean BMI for non-surviving patients was significantly higher compared to patients surviving on the seventh day of hospitalization (35 vs. 30 kg/m², P = 0.022). Similarly, patients requiring IMV had a higher BMI (33 vs. 29, P = 0.002) compared to nonintubated patients. The unadjusted OR for patients with a higher BMI requiring IMV (56% vs. 28%, OR: 3.3, 95% CI: 1.6 - 7.0, P = 0.002) and upgrade to ICU (46% vs. 28%, OR; 2.2, 1.07 - 4.6, P = 0.04) were significantly higher compared to patients with a lower BMI. Similarly, patients with a higher BMI had higher in-hospital mortality (21% vs. 9%, OR: 3.2, 95% CI: 1.3 - 8.2, P = 0.01) compared to patients with a normal BMI. Despite a numerical advantage in the lower BMI group, there was no significant difference between the two groups in terms of the need for dialysis (5% vs. 13%, OR: 3.8, 13% vs. 4%, 1.1 - 14.1, P = 0.07). aORs controlled for baseline comorbidities and medications mirrored the overall results, except for the need to upgrade to ICU. Conclusions: In patients with confirmed COVID-19, morbid obesity serves as an independent risk factor of high in-hospital mortality and the need for IMV.