To better guide strategies intended to reduce high rates of 30-day readmission after hospitalization for heart failure, acute myocardial infarction, or pneumonia, further information is needed about readmission diagnoses, readmission timing, and the relationship of both to patient age, sex, and race.

To examine readmission diagnoses and timing among Medicare beneficiaries readmitted within 30 days after hospitalization for heart failure, acute myocardial infarction, or pneumonia.

We analyzed 2007 to 2009 Medicare Fee-For-Service claims data to identify patterns of 30-day readmission by patient demographic characteristics and time after hospitalization for heart failure, acute myocardial infarction, or pneumonia. Readmission diagnoses were categorized using an aggregated version of the Centers for Medicare & Medicaid Services’ Condition Categories. Readmission timing was determined by day after discharge.

We examined (1) the percentage of 30-day readmissions occurring on each day (0–30) after discharge; (2) the most common readmission diagnoses occurring during cumulative time periods (days 0–3, 0–7, 0–15, and 0–30) and consecutive time periods (days 0–3, 4–7, 8–15, and 16–30) after hospitalization; (3) median time to readmission for common readmission diagnoses; and (4) the relationship between patient demographic characteristics and readmission diagnoses and timing.

From 2007 to 2009, we identified 329,308 30-day readmissions after 1,330,157 heart failure hospitalizations (24.8% readmitted), 108,992 30-day readmissions after 548,834 acute myocardial infarction hospitalizations (19.9% readmitted), and 214,239 30-day readmissions after 1,168,624 pneumonia hospitalizations (18.3% readmitted). The proportion of patients readmitted for the same condition was 35.2% after index heart failure hospitalization, 10.0% after index acute myocardial infarction hospitalization, and 22.4% after index pneumonia hospitalization. Of all readmissions within 30 days, 61.0%, 67.6%, and 62.6% occurred with 15 days of discharge after hospitalization for heart failure, acute myocardial infarction, or pneumonia, respectively. The diverse spectrum of readmission diagnoses was largely similar in both cumulative (days 0–3, 0–7, 0–15, and 0–30) and consecutive (days 0–3, 4–7, 8–15, and 16–30) time periods after discharge. Median time to 30-day readmission was 12 days, 10 days, and 12 days for patients initially hospitalized with heart failure, acute myocardial infarction, or pneumonia, respectively, and was comparable across common readmission diagnoses. Neither readmission diagnoses nor timing substantively varied by age, sex, or race.

Among Medicare Fee-for-Service beneficiaries hospitalized for heart failure, acute myocardial infarction, or pneumonia, 30-day readmissions are frequent throughout the month following hospitalization and result from a similar spectrum of readmission diagnoses regardless of age, sex, race, or time after discharge.