Association between Body Mass Index and Hospital Outcomes for COVID-19 Patients: A Nationwide Study

Background: Coronavirus disease 2019 (COVID-19) caused significant morbidity and mortality worldwide. There is limited information describing the hospital outcomes of COVID-19 patients in regard to specific body mass index (BMI) categories. Methods: We utilized the Healthcare Cost and Utilization Project Nationwide Inpatient Sample (NIS) 2020 database to collect information on patients hospitalized for COVID-19 in the United States. Using the International Classification of Diseases, 10th revision, Clinical Modification (ICD-10-CM) coding system, adult patients (≥18 years of age) with a primary hospitalization for COVID-19 were identified. Adjusted analyses were performed to assess for mortality, morbidity, and resource utilization, and compare the outcomes among patients categorized according to BMI. Results: A total of 305,284 patients were included in this study. Of them, 248,490 had underlying obesity, defined as BMI ≥ 30. The oldest patients were observed to have BMI < 19, while youngest patients were in the BMI > 50 category. BMI < 19 category had the highest crude in-hospital mortality rate. However, after adjusted regression, patients with BMI > 50 (adjusted odds ratio (aOR) 1.63, 95% CI 1.48–1.79, p-value < 0.001) had the highest increased odds, at 63%, of in-hospital mortality compared to all other patients in the study. Patients with BMI > 50 also had the highest increased odds of needing invasive mechanical ventilation (IMV) and mortality associated with IMV compared to all other patient, by 37% and 61%, respectively. Obese patients were noted to have shorter average hospital length of stay (LOS), by 1.07 days, compared to non-obese patients, but there was no significant difference in average hospitalization charges. Conclusion: Among obese patients primarily hospitalized with COVID-19, those with BMI ≥ 40 had significantly increased rates of all-cause in-hospital mortality, need for IMV, mortality associated with IMV, and septic shock. Overall, obese patients had shorter average hospital LOS, however, did not have significantly higher hospitalization charges.