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What explains black-white differences in survival in idiopathic dilated cardiomyopathy? The Washington, DC, Dilated
S S Coughlin1, L Myers, R K Michaels
1Department of Biostatistics and Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA.
Insights
In idiopathic dilated cardiomyopathy patients, race was initially linked to mortality. However, further analysis suggests socioeconomic factors, not race itself, may explain these disparities in survival outcomes.
Area of Science:
- Cardiology
- Public Health
- Health Disparities
Background:
- Previous analyses suggested race as an independent predictor of mortality in idiopathic dilated cardiomyopathy.
- These initial findings were based on limited follow-up data (12-24 months).
Purpose of the Study:
- To re-examine the association between race and mortality in idiopathic dilated cardiomyopathy with extended follow-up (up to 5 years).
- To investigate whether socioeconomic factors mediate the observed association between race and mortality.
Main Methods:
- Analysis of 128 patients with idiopathic dilated cardiomyopathy from Washington, DC area hospitals.
- Inclusion of up to 5 years of follow-up data.
- Univariate and multivariable proportional hazards analyses, adjusting for socioeconomic variables.
Main Results:
- Black patients (80.5%) had lower income, education, and private health insurance compared to white patients.
- While univariate analysis showed a borderline association between black race and mortality, multivariable analysis found age and ejection fraction as significant predictors.
- The association between race and mortality was nonsignificant after adjusting for income and health insurance type, suggesting socioeconomic factors play a role.
Conclusions:
- The previously observed association between black race and increased mortality in idiopathic dilated cardiomyopathy may be explained by socioeconomic factors.
- Access to healthcare, influenced by income and insurance, appears to be a critical factor in survival disparities.
Abstract:
We have found race to be an independent predictor of mortality in a preliminary analysis of data from an ongoing study of patients with idiopathic dilated cardiomyopathy. Our previous, analyses, however, were based on only 12 to 24 months of follow-up. In the present analysis, which is based on up to 5 years of follow-up, we extended our earlier observations and examined whether other socioeconomic factors account for the association with race. A total of 128 patients from five Washington, DC, area hospitals were included in the analysis. One hundred three (80.5%) of the patients were black and 25 (19.5%) were white. The black patients were less likely to have private health insurance, less educated on average, and more likely to have a household income < or = $15,000. No racial differences were found in cardiac medication usage, with the exception of beta blockers and antiarrhythmics. The cumulated survival among black patients at 12 and 60 months was 71.5% and 39.1%, respectively, compared with 92% and 31.4% among whites. Age, ventricular arrhythmias, and ejection fraction were significant predictors of survival in univariate analysis. The univariate association with black race was of borderline significance. In multivariable analysis using the proportional hazards model, age and ejection fraction were significant independent predictors of survival. The association with ventricular arrhythmias was of borderline significance. The association with black race, which was statistically nonsignificant, was diminished even further by adjustment for income and type of health insurance. Thus, the previously reported association with black race may be accounted for by socioeconomic factors related to access to health care.