. As of April 30, 2020, over 1 million individuals in the U.S. have been diagnosed with coronavirus disease 2019 (COVID-19). Patients with COVID-19 may develop various symptoms ? while the majority 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 are more likely to be hospitalized or die. Studies have suggested that some underlying conditions, such as hypertension, diabetes, or obesity, are associated with the severity of COVID-19. However, it is unknown to what extent these comorbidities explain the variation in the severity of COVID-19, whether older age is independently associated with the severity of COVID-19; and whether and how older age modifies the relationship between comorbidities and the severity of COVID-19. Second, it has been reported that black Americans 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 the characteristics of the community where they reside in, or due to some other factors that are also associated with race. The objective of this study is to identify individual risk factors that are associated with the severity of COVID-19 (i.e. hospitalizations, ICU use and death), especially among older adults, and to understand reasons that 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 veterans diagnosed 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) To identify individual risk factors that are associated with COVID-19 related hospitalizations, ICU use and mortality, 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 among veterans diagnosed with COVID-19: whether and how such difference is related to individual factors and community characteristics, especially socio-economic status. This study is innovative because it will be the first study to examine the role of multiple risk factors in the severity of COVID-19 by using national data with detailed individual-level information and machine learning algorithm; and it will be the first to examine the reasons, including the role of social determinants, for racial differences in COVID-19 severity. This proposed research is significant as it will help to identify patients with the highest-risk phenotypes, thus providing insights into disease prevention and resource allocation.
This proposed research aims to understand risks factors associated with the severity of COVID-19 (i.e. hospitalization, ICU use and death) and the role of older age in the severity of COVID-19; and to examine reasons leading to racial differences in the severity of COVID-19. This proposed research is highly relevant to public health because the findings from this study will help target prevention strategies and allocation of resources to high-risk populations and help fight this novel infectious disease.
