Researchers analyzing Medicare admission and readmission records found no correlation between age, race and gender and rates of readmission after an index admission for heart failure (HF), MI or pneumonia. These results were published online Jan. 23 in the Journal of the American Medical Association.

Kumar Dharmarajan, MD, MBA, post-doctoral research fellow at the Yale School of Medicine in New Haven, Conn., and colleagues identified hospitalizations at acute-care hospitals with diagnoses of HF, MI or pneumonia from 2007 through 2009, using Medicare Standard Analytic and Denominator files. They then extracted records of patients who were readmitted for any reason within 30 days of discharge. In cases of repeat rehospitalization within the 30-day period, only the first rehospitalization was counted. The rehospitalized patients were categorized according to:

• Diagnosis on index admission and readmission;
• Age (65 to 74, 75 to 84, and 85 and older);
• Race (black, white and other); and
• Gender.

The analysis also included time to readmission.

The researchers found 1,330,157 hospitalizations for HF, and 24.8 percent of these patients were readmitted. The cause of readmission was most often cardiovascular disease (52.8 percent), particularly HF (35.2 percent).

There were 548,834 admissions for acute MI, of whom 19.9 percent were readmitted. Cardiovascular disease was the reason for readmission in 53.4 percent of cases, most often HF (19.3 percent).  

Patients hospitalized for pneumonia numbered 1,168,624, and 18.3 percent were rehospitalized within 30 days of index discharge. Respiratory disease was the cause of readmission in 38.5 percent of cases, and recurrent pneumonia was the most common diagnosis (22.4 percent).

For all three index diagnoses, over 60 percent of the 30-day readmissions occurred within zero to 15 days after discharge.

The researchers used extended logistic regression models for the five most frequent readmission diagnoses for each condition and adjusted for comorbidities, then calculated the predicted number of readmissions and compared it to the actual number of readmissions for each demographic group. They also fit extended Cox proportional hazard models to estimate comorbidity-adjusted hazard ratios for each demographic characteristic. Dharmarajan et al found no clinically significant differences in either readmission diagnosis or time to readmission associated with demographic characteristics.

“[T]he overall pattern of diagnoses responsible for readmission did not substantively differ by patient demographic characteristics or time after discharge,” the study authors wrote.

Noting this, as well as the fact that the large majority of readmissions were with diagnoses that differed from the diagnosis on index admission, the researchers postulated that “post-hospital syndrome—a generalized vulnerability to illness among recently discharged patients, many of whom have developed new impairments, both during and after hospitalization,” may be to blame. They suggested that “a generalized approach to preventing readmissions that is broadly applicable across potential readmission diagnoses and effective for at least the full month after hospitalization” may be the best strategy.