Factors associated with hospitalization, ICU use and death among vulnerable populations diagnosed with COVID-19

Project Summary. As of April 30, 2020, over 1 million individuals in the U.S. have been diagnosed withcoronavirus disease 2019 (COVID-19). Patients with COVID-19 may develop various symptoms - while themajority of patients have mild symptoms, some require hospitalization, admissions to intensive care unit (ICU),and may die. To date, there is only limited knowledge on risk factors associated with the severity of COVID-19.First, older adults have been found to have higher risks of developing severe symptoms of COVID-19 and aremore likely to be hospitalized or die. Studies have suggested that some underlying conditions, such ashypertension, diabetes, or obesity, are associated with the severity of COVID-19. However, it is unknown towhat extent these comorbidities explain the variation in the severity of COVID-19, whether older age isindependently associated with the severity of COVID-19; and whether and how older age modifies therelationship between comorbidities and the severity of COVID-19. Second, it has been reported that blackAmericans experienced a higher rate of COVID-related hospitalization and were more likely to die of COVID-19, compared to white Americans. However, it is unknown what may contribute to such racial difference -whether it is due to the differences in health conditions between blacks and whites, or due to thecharacteristics of the community where they reside in, or due to some other factors that are also associatedwith race. The objective of this study is to identify individual risk factors that are associated with the severity ofCOVID-19 (i.e. hospitalizations, ICU use and death), especially among older adults, and to understand reasonsthat may contribute to racial differences in COVID-19 severity. To achieve these goals, we will use the daily-updated national Veterans Affairs (VA) data, which contain rich individual-level information on veteransdiagnosed with COVID-19. As of April 30, 2020, almost 9,000 veterans have been diagnosed with COVID-19,and about 500 had died, thus providing a large study cohort. This proposed study has two Specific Aims:1) Toidentify individual risk factors that are associated with COVID-19 related hospitalizations, ICU use andmortality, to understand the role of older age in COVID-19 severity, and to build a predictive model for COVID-19 severity by machine learning; and 2) To examine reasons for racial differences in illness severity amongveterans diagnosed with COVID-19: whether and how such difference is related to individual factors andcommunity characteristics, especially socio-economic status. This study is innovative because it will be the firststudy to examine the role of multiple risk factors in the severity of COVID-19 by using national data withdetailed individual-level information and machine learning algorithm; and it will be the first to examine thereasons, including the role of social determinants, for racial differences in COVID-19 severity. This proposedresearch is significant as it will help to identify patients with the highest-risk phenotypes, thus providing insightsinto disease prevention and resource allocation.