Socioeconomic status as an independent risk factor for hospital readmission for heart failure.

The management of heart failure is characterized by high rates of hospital admission as well as rehospitalization after inpatient treatment of this disorder, whereas skillful medical care may reduce the risk of hospital admission. The purpose of this study was to examine the relation between income (as a measure of socioeconomic status) and the frequency of hospital readmission among a large and diverse group of persons treated for heart failure. We analyzed administrative discharge data from 236 nonfederal acute-care hospitals in New York State, involving 41,776 African-American or Caucasian hospital survivors with International Classification of Diseases, Ninth Revision, Clinical Modification codes for heart failure in the principal diagnosis position between January 1 and December 31, 1995. Household income was derived from postal ZIP codes and census data. We found that patients residing in lower income neighborhoods were more often women or African-Americans, had more comorbid illness, had higher use of Medicaid insurance, and were more often admitted to rural hospitals. There was a stepwise decrease in the crude frequency of readmission from the lowest quartile of income (23.2%) to the highest (20.0%) (p <0.0001 for Mantel-Haenszel chi-square test for trend across all quartiles; p <0.0001 for comparison between quartiles 1 and 4). After adjustment for baseline differences and process of care, income remained a significant predictor, with an increase in the risk of readmission noted in association with lower levels of income (adjusted odds ratio for quartile 1:4 comparison, 1.18; 95% confidence interval, 1.10 to 1.26, p <0.0001). We conclude that lower income patients hospitalized for treatment of heart failure in New York differ from higher income patients in important clinical and demographic comparisons. Even after adjustment for these fundamental differences and other potential confounding factors, lower income is a positive predictor of readmission risk.