Racial Disparities in Odds of 30-Day Hospital Readmission in a Medicare Population

April 18, 2011

Tori Socha

It has been well documented that racial disparities exist in healthcare, but little is known about disparities in rates of hospital readmissions between black patients and white patients. Reducing readmissions has gained attention as a policy focus because of the potential to reduce costs while improving quality of care. Researchers who hypothesized that understanding whether and why there are racial disparities in readmissions would have implications for efforts to reduce readmissions recently conducted a study to determine whether black patients have higher odds of readmission than white patients and whether these disparities are related to where black patients are treated. They reported study results in the Journal of the American Medical Association [2011;307(7):675-681].

The study defined hospitals in the top decile of proportion of black patients as minority-serving; the researchers determined the odds of readmission for black patients compared with white patients at minority-serving versus non–minority-serving hospitals. The primary outcome measure of the study was the risk-adjusted odds of a 30-day readmission. The researchers utilized the Medicare Provider Analysis Review 100% files to examine all hospitalizations between January 1, 2006, and November 30, 2008, with a primary discharge diagnosis of acute myocardial infarction (MI), congestive heart failure, or pneumonia. The diagnoses were identified using International Classification of Diseases, Ninth Revision, Clinical Modification codes. Eligible patients were Medicare fee-for-service beneficiaries ≥65 years of age.

The final study cohort included 3,163,011 discharges. Of those, 8.7% (n=276,681) were for black patients and 91.3% (n=2,886,330) were for white patients. For each of the 3 conditions, black patients were younger, more likely to be female, more likely to have diabetes, hypertension, chronic kidney disease, and obesity, and less likely to have chronic pulmonary disease, valvular heart disease, and depression. Approximately 40% of black patients were treated at minority-serving hospitals compared with 6% of white patients. On average, at minority-serving hospitals, 37% of patients were black compared with 1.4% of patients at non–minority-serving hospitals. White patients at non–minority-serving hospitals consistently had the lowest odds of readmission, and black patients at minority-serving hospitals had the highest rates of readmission.

When patients with the 3 conditions were considered as a single sample, black patients had 13% higher odds of all-cause 30-day readmission compared with white patients (odds ratio [OR], 1.13; 95% confidence interval [CI], 1.11-1.14; P<.001); patients discharged from minority-serving hospitals had 23% higher odds of readmission compared with patients discharged from non–minority-serving hospitals (OR, 1.23; 95% CI, 1.20-1.27; P<.001). The researchers also analyzed data for the 3 conditions separately and examined patient race and site of treatment simultaneously, finding that both factors were significantly associated with readmission rates. Compared with white patients from non–minority-serving hospitals, for patients with acute MI, the odds of readmission for black patients were 13% higher (OR, 1.13; 95% CI, 1.10-1.16; P<.001), irrespective of site of care. Patients from non–minority-serving hospitals had 22% higher odds of readmissions (OR, 1.22; 95% CI, 1.17-1.27; P<.001), even accounting for race. Analyses for the other 2 conditions were similar.

The results were unchanged following adjustment for hospital characteristics including markers of caring for poor patients. In conclusion, the researchers noted that “among elderly Medicare recipients, black patients were more likely to be readmitted after hospitalization for 3 common conditions, a gap that was related to both race and to the site where care was received.”