Racial difference in mortality among COVID-19 hospitalizations in California

A total of 87,934 COVID-19 hospitalizations were included for the analysis. The majority of them were Hispanics (56.5%), followed by Whites (27.3%), Asian, Pacific Islander, Native American (9.9%), and Blacks (6.3%). The age distribution of the sample showed that the majority were between the ages 45–85 years. Among Hispanic hospitalizations, significant majority (43.9%) were in the age group 45–64 years, while among Whites (46.5%) and Asian, Pacific Islander, Native American (40.0%), majority were in the age group 65–84 years. There were greater proportions of male hospitalizations in the total sample as well as in all racial groups. The majority of the patients in the total sample had Medicare coverage (43.4%). Hispanics differed from other races with the respect to insurance coverage since the majority of them had Medicaid, whereas the majority in other races had Medicare coverage. The most common comorbidities observed in the total sample were hypertension (61.6%), hyperlipidemia (39.3%), obesity (28.1%), chronic renal failure (19.3%), and chronic pulmonary disease (18.9%). The rates of atrial fibrillation, coagulation disorder, and peripheral vascular disease were highest among Whites, whereas the rates of hypertension, hyperlipidemia, chronic renal failure, tobacco use, alcohol abuse, drug abuse, stroke, congestive heart failure, chronic pulmonary disease, metastatic cancer, and anemia were highest among Blacks. The rates of diabetes mellitus, obesity, and liver disease were highest among Hispanics. Elixhauser comorbidity index ≥ 3 was observed among 59.4% of total sample and was substantially higher among Blacks (73.6%), followed by Whites (68.4%), Asian, Pacific Islander, Native American (59.2%), and Hispanics (53.5%). All demographic and clinical characteristics showed significant differences between racial groups (Table 1).

Among total hospitalizations, all-cause, in-hospital mortality was 11.5%. Of these hospitalizations, 9.8% had ICU admission, whereas 90.2% did not. Among hospitalizations with ICU admission, 35.8% were discharged alive whereas 64.2% died. Among hospitalizations with ICU admission, mortality rates were highest among Hispanics (63.6%), followed by Whites (21.1%), Asian, Pacific Islander, Native American (9.5%), and Blacks (5.6%). Among hospitalizations without ICU admission, 94.2% were discharged alive whereas 5.8% died. Among hospitalizations without ICU admission, mortality rates were highest among Whites (42.1%), followed by Hispanics (40.6%), Asian, Pacific Islander, Native American (11.3%), and Blacks (5.8%). Figure 1 shows ICU admission and in-hospital mortality among COVID-19 hospitalizations.

ICU admission and in-hospital mortality among COVID-19 hospitalizations (N = 87,934).

Survival analysis stratified by race showed that Hispanics had the lowest survival rates, followed by Asian, Pacific Islander, Native American, Whites, and Blacks. Survival rates differed significantly between the races (Logrank P < 0.001). Figure 2 shows Kaplan Meier curves for in-hospital mortality among COVID-19 hospitalizations stratified by race.

Kaplan Meier curves showing in-hospital mortality rates among COVID-19 hospitalizations stratified by race.

Cox proportional regression analysis showed that the risk of mortality was significantly higher among Hispanics, compared to Whites (HR, 0.91; 95% CI 0.87–0.96), Blacks (HR, 0.87; 95% CI 0.79–0.94), and Asian, Pacific Islander, Native American (HR, 0.89; 95% CI 0.83–0.95). The risk of mortality was also significantly higher across increasing age groups and among men (HR, 1.16; 95% CI 1.11–1.21). The comorbidities associated with greater risk of mortality were diabetes mellitus (HR, 1.20; 95% CI 1.13–1.27), obesity (HR, 1.07; 95% CI 1.02–1.12), atrial fibrillation HR, 1.38; 95% CI 1.31–1.44), coagulation disorder (HR, 1.15; 95% CI 1.10–1.20), liver disease (HR, 1.37; 95% CI 1.28–1.47), chronic renal failure (HR, 1.36; 95% CI 1.29–1.42), congestive heart failure (HR, 1.23; 95% CI 1.17–1.29), and metastatic cancer (HR, 1.59; 95% CI 1.36–1.87). Table 2 shows hazard ratios for in-hospital mortality among COVID-19 hospitalizations. Cox proportional regression analysis with interaction between race and factors such as age, sex, diabetes, obesity, and hypertension did not show any significant interactions (Supplementary Table 1).

Comparison of ICU admission rates among racial groups showed that, ICU admission was highest among Hispanics (n = 5494, 11.1%), followed by Asian, Pacific Islander, Native American (n = 840, 9.6%), Blacks (n = 480, 8.7%), and Whites (1758, 7.3%). Logistic regression analysis showed that the odds of ICU admission were significantly higher among Hispanics, compared to Whites (OR, 1.70; 95% CI 1.67–1.74), Blacks (OR, 1.70; 95% CI 1.64–1.78), and Asian, Pacific Islander, Native American (OR, 1.82; 95% CI 1.76–1.89). Table 3 shows the full model. Logistic regression analysis with interaction between race and factors such as age, sex, diabetes, obesity, and hypertension did not show any significant interactions (Supplementary Table 2).