Background: Various healthcare systems have consistently reported the high prevalence of obesity and obesity-related complications among patients with severe COVID-19, and among patients dying from COVID-19. However, there are conflicting findings as to whether obesity independently predicts severe disease and mortality.

Objectives: To evaluate the impact of obesity on in-hospital mortality among patients hospitalized in the national Veterans Affairs (VA) Healthcare System with COVID-19.

Methods: We included hospitalized Veterans with positive COVID-19 PCR tests from Mar 1, 2020 – Nov 30, 2020. Class 3 obesity (severe obesity) was assessed at the time of the index date (the earliest of either the first positive COVID-19 PCR test date or hospital admission date) and defined as body mass index (BMI) >=40 kg/m2. Comorbidities were assessed from the index date through the previous two years. A multivariable logistic regression model with backward elimination was utilized to assess the association of severe obesity with inpatient mortality, controlling for other risk factors of COVID-19 mortality. In sensitivity analyses, obesity (BMI >= 30 kg/m2) and sleep apnea (which affected 32.2% of our cohort) were assessed as independent predictors of mortality.

Results: The in-hospital mortality rate among our cohort of 16,551 patients hospitalized with COVID-19 was 11.7%. There were numerous significant differences between patients who did not survive the hospitalization and those who did in terms of comorbidity burden (mean age 76.2 vs 67.8, Elixhauser comorbidity index 11 vs 7, p<0.05). When controlling for other risk factors associated with COVID-19 mortality, severe obesity (BMI >=40 kg/m2) was an independent predictor of inpatient mortality (adjusted odds ratio [aOR] 1.43, 95% confidence interval [CI] 1.16-1.75). However, obesity (BMI >=30 kg/m2, aOR 1.09, 95 CI 0.97-1.22) and sleep apnea were not (aOR 0.97, 95% CI 0.86-1.09).

Conclusions: In our national cohort study of patients hospitalized with COVID-19, severe obesity was an independent risk factor for mortality, increasing the risk of in-hospital death by 43%. As governmental bodies and public health departments develop COVID-19 vaccination eligibility criteria for individuals with “underlying medical conditions”, factors that have been shown to be independently predictive of severe disease and death in various populations should be prioritized.