Racial disparities persist after controlling for age, sex, socioeconomic status, or comorbidities

Black patients were more likely to be hospitalized with Covid-19 than white patients, even when they had similar health and socioeconomic conditions, suggesting that racial disparities in Covid-19 outcomes cannot be explained by considering age, sex, socioeconomic status, or comorbidities, according to a study from the University of Michigan.

In addition, patients with preexisting type 2 diabetes or kidney disease and those who live in high-population density areas were more likely to require hospitalization for Covid-19, Bhramar Mukherjee, PhD, of the Department of Biostatistics at the University of Michigan School of Public Health and the Rogel Cancer Center at University of Michigan Medicine in Ann Arbor, Michigan, and colleagues reported in JAMA Network Open. The study authors did not find statistically significant racial differences in ICU admission and mortality.

As the Covid-19 pandemic rages on across the U.S., minority populations continue to bear a greater disease burden — for example, in Michigan, Black people make up 14% of the population but account for 21% of Covid-19 cases and 37% of Covid-related deaths, Mukherjee and colleagues noted, and similar trends have appeared across multiple states.

For their analysis, Mukherjee and colleagues set out to determine sociodemographic characteristics and comorbid conditions associated with Covid-19 outcomes — positive test results, hospitalization, admission to ICU, and mortality — by race/ethnicity.

“Our association results do not explain why there are differences in Covid-19 outcomes associated with race; thus, the idea of structural factors influencing health is pivotal,” they wrote.

For this retrospective cohort study, Mukherjee and colleagues used “comparative groups of patients tested or treated for Covid-19 at the University of Michigan from March 10, 2020, to April 22, 2020, with an outcome update through July 28, 2020,” they explained. “A group of randomly selected untested individuals were included for comparison. Examined factors included race/ethnicity, age, smoking, alcohol consumption, comorbidities, body mass index (BMI; calculated as weight in kilograms divided by height in meters squared), and residential-level socioeconomic characteristics.”

The study’s main outcomes were being tested for Covid-19, having positive test results or being diagnosed, hospitalization, needing ICU treatment, and inpatient/outpatient Covid-19–related mortality. Data was pulled from electronic health records (EHRs) in the University of Michigan Health System. The study cohort included 5,698 patients who were tested for Covid-19 (mean [SD] age, 47.4 [20.9] years; 2,167 [38.0%] men; mean [SD] BMI 30 [8.0]), of whom 1,139 (20.0%) had tested positive — the comparison group included 7,168 individuals who were not tested (mean [SD] age, 43.1 [24.1] years; 3,257 [45.4%] men; mean [SD] BMI 28.5 [7.1]). The majority of the tested cohort were either white (3,740 [65.6%]) or Black (1,058 [18.6%]).

“Among 1,139 patients diagnosed with Covid-19, 492 (43.2%) were White and 442 (38.8%) were Black; 523 (45.9%) were hospitalized, 283 (24.7%) were admitted to the ICU, and 88 (7.7%) died,” they found. “Adjusting for age, sex, socioeconomic status, and comorbidity score, Black patients were more likely to be hospitalized compared with White patients (OR, 1.72 [95% CI, 1.15-2.58]; P= 0.009). In addition to older age, male sex, and obesity, living in densely populated areas was associated with increased risk of hospitalization (OR, 1.10 [95% CI, 1.01-1.19]; P= 0.02). In the overall population, higher risk of hospitalization was also observed in patients with preexisting type 2 diabetes (OR, 1.82 [95% CI, 1.25-2.64]; P= 0.02) and kidney disease (OR, 2.87 [95% CI, 1.87-4.42]; P< 0.001).”

Also among the findings:

  • Obesity was associated with higher risk of having positive Covid-19 test results among Black patients (OR, 3.11 [95% CI, 1.64-5.90]; P< 0.001) compared with white patients (OR, 1.37 [95% CI, 1.01-1.84]; P=0.04; P for interaction= 0.02).
  • Having any cancer was associated with higher risk of having positive Covid-19 test results among Black patients (OR, 1.82 [95% CI, 1.19-2.78]; P= 0.005) but not white patients (OR, 1.08 [95% CI, 0.84-1.40]; P= 0.53; P for interaction = 0.04).
  • Overall comorbidity burden was associated with higher risk of hospitalization in white patients (OR, 1.30 [95% CI, 1.11-1.53]; P= 0.001) but not Black patients (OR, 0.99 [95% CI, 0.83-1.17]; P= 0.88; P for interaction= 0.02), as was type 2 diabetes (White: OR, 2.59 [95% CI, 1.49-4.48]; P< 0.001; Black: OR, 1.17 [95% CI, 0.66-2.06]; P= 0.59; P for interaction = 0.046).
  • No statistically significant racial differences were found in ICU admission and mortality based on adjusted analysis.

“Supplementary analysis indicated that among patients with positive Covid-19 test results, Black patients had a significantly higher comorbidity score prior to Covid-19 testing compared with white patients and had a higher symptom burden at the time of getting tested,” they added.

Mukherjee noted that their findings are consistent with other existing studies. “Male sex was associated with a higher risk of hospitalization and death, especially among individuals 50 years and older,” they wrote. “Similarly, health conditions, such as obesity, cancer, type 2 diabetes, and renal conditions, were prevalent among patients with worse Covid-19 outcomes. Notably, our findings largely agree with recent published work examining racial/ethnic differences in Covid-19 outcomes, which found Black patients had a higher hospitalization rate, increased odds of positive test results, and disproportionately high Covid-19 diagnosis rate compared with white patients.”

These findings highlight that poor Covid-19 outcomes are disproportionately associated with at-risk populations, including elderly adults, those with preexisting conditions, and those in population-dense communities, the study authors concluded. “Our results support targeted screening for elderly adults and those with type 2 diabetes and kidney disease,” they wrote. “Moreover, we call for increased investments in testing and prevention efforts in lower–socioeconomic status, densely populated, and racially diverse communities. It is these same communities that are home to a greater proportion of essential workers and thus need increased testing and protection.”

“Knowing risk profiles associated with severe Covid outcomes can help us protect ourselves and protect the most vulnerable,” said study co-author Tian Gu, MS, of the University of Michigan School of Public Health, in a report published by the university. “This calls for strategic action plans to eliminate health inequities that have persisted in our social system.”

Mukherjee and colleagues noted several limitations to their study, including possibly missing some hospitalized patients by only using data from the University of Michigan Health System and not considering the small number of transfer patients from other hospitals as a special subgroup, although they often have more severe outcomes. Also, “one may argue that the comparison group is intrinsically different than the tested cohort and does not serve as a proper comparison group, which may impact the estimation of the ORs observed in the susceptibility models,” they added.

  1. A University of Michigan study found that, after controlling for age, sex, socioeconomic status, or comorbidities, Black individuals and people with type 2 diabetes or kidney disease were more likely to require hospitalization for Covid-19.

  2. These findings suggest that targeted interventions to support high-risk populations are necessary to address racial disparities that cannot be explained by controlling for age, sex, socioeconomic status, and comorbidity score.

John McKenna, Associate Editor, BreakingMED™

This study was funded by the University of Michigan Precision Health Initiative, University of Michigan Rogel Cancer Center, and Michigan Institute of Data Science. Mukherjee’s research was funded by grant No. NSF DMS 1712933 from the National Science Foundation, and Fritsche’s research was supported by grant No. CA 046592 from the National Cancer Institute, National Institutes of Health.

Coauthor Singh reported receiving salary support from Blue Cross Blue Shield of Michigan outside the submitted work. Coauthor Nallamothu reported serving as a principal investigator or coinvestigator on research grants from the National Institutes of Health (NIH), U.S. Department of Veterans Affairs Health Services Research and Development, and the American Heart Association; receiving personal fees as Editor-in-Chief of Circulation: Cardiovascular Quality & Outcomes

No other disclosures were reported.

Cat ID: 190

Topic ID: 79,190,730,933,190,926,192,927,925,934