COVID-19 outcomes, risk factors and associations by race: a comprehensive analysis using electronic health records data in Michigan Medicine
Authors: Gu Tian , Mack Jasmine A. , Salvatore Maxwell , Sankar Swaraaj Prabhu , Valley Thomas S. , Singh Karandeep , Nallamothu Brahmajee K. , Kheterpal Sachin , Lisabeth Lynda , Fritsche Lars G. , Mukherjee Bhramar 
Published: June 2020

Structured AbstractImportanceBlacks/African-Americans are overrepresented in the number of COVID-19 infections, hospitalizations and deaths. Reasons for this disparity have not been well-characterized but may be due to underlying comorbidities or sociodemographic factors.ObjectiveTo systematically determine patient characteristics associated with racial/ethnic disparities in COVID-19 outcomes.DesignA retrospective cohort study with comparative control groups.SettingPatients tested for COVID-19 at University of Michigan Medicine from March 10, 2020 to April 22, 2020.Participants5,698 tested patients and two sets of comparison groups who were not tested for COVID-19: randomly selected unmatched controls (n = 7,211) and frequency-matched controls by race, age, and sex (n = 13,351).Main Outcomes and MeasuresWe identified factors associated with testing and testing positive for COVID-19, being hospitalized, requiring intensive care unit (ICU) admission, and mortality (in/out-patient during the time frame). Factors included race/ethnicity, age, smoking, alcohol consumption, healthcare utilization, and residential-level socioeconomic characteristics (SES; i.e., education, unemployment, population density, and poverty rate). Medical comorbidities were defined from the International Classification of Diseases (ICD) codes, and were aggregated into a comorbidity score.ResultsOf 5,698 patients, (median age, 47 years; 38% male; mean BMI, 30.1), the majority were non-Hispanic Whites (NHW, 59.2%) and non-Hispanic Black/African-Americans (NHAA, 17.2%). Among 1,119 diagnosed, there were 41.2% NHW and 37.4% NHAA; 44.8% hospitalized, 20.6% admitted to ICU, and 3.8% died. Adjusting for age, sex, and SES, NHAA were 1.66 times more likely to be hospitalized (95% CI, 1.09-2.52; P=.02), 1.52 times more likely to enter ICU (95% CI, 0.92-2.52; P=.10). In addition to older age, male sex and obesity, high population density neighborhood (OR, 1.27 associated with one SD change [95% CI, 1.20-1.76]; P=.02) was associated with hospitalization. Pre-existing kidney disease led to 2.55 times higher risk of hospitalization (95% CI, 1.62-4.02; P<.001) in the overall population and 11.9 times higher mortality risk in NHAA (95% CI, 2.2-64.7, P=.004).Conclusions and RelevancePre-existing type II diabetes/kidney diseases and living in high population density areas were associated with high risk for COVID-19 susceptibility and poor prognosis. Association of risk factors with COVID-19 outcomes differed by race. NHAA patients were disproportionately affected by obesity and kidney disease.Key PointsQuestionWhat are the sociodemographic and pre-existing health conditions associated with COVID-19 outcomes and how do they differ by race/ethnicity?FindingsIn this retrospective cohort of 5,698 patients tested for COVID-19, high population density and comorbidities such as type II diabetes/kidney disease were associated with hospitalization, in addition to older age, male sex and obesity. Adjusting for covariates, non-Hispanic Blacks were 1.66 times more likely to be hospitalized and 1.52 times more likely to be admitted to ICUs than non-Hispanic Whites.MeaningTargeted interventions to support vulnerable populations are needed. Racial disparities existed in COVID-19 outcomes that cannot be explained after controlling for age, sex, and socioeconomic status.