Background: Few studies have examined rates, characteristics, and costs of 30-day readmissions across the spectrum of age and insurance. In this setting, the relative impact of non-Medicare readmissions is unknown.
Methods: Discharges of patients ≥18 hospitalized for any cause 1/1/13 - 11/30/13 at 2,006 hospitals in the Nationwide Readmissions Database (NRD), an 85% sample of hospital discharges from 21 states, were included. Results were stratified by age (18-44, 45-64, ≥65) and insurance (Medicare, Medicaid, private insurance, self-pay, and unknown). Outcomes included rates of 30-day readmission, index hospitalization diagnoses associated with readmission, and total direct costs of readmissions determined using hospital charges and the NRD Cost to Charge ratio. A hierarchical logistic regression model was used to examine the association between insurance and readmission risk, adjusting for age, admission source, and Elixhauser comorbidities, including a random effect for hospital. Dual eligible patients are classified according to primary insurance in the NRD.
Results: Among 12,533,551 discharges, 1,818,093 (14.5%) resulted in readmission within 30 days. Medicaid insurance was associated with the highest adjusted odds ratio (AOR) for readmission both in those ≥65 years old (AOR 1.12, 95%CI 1.10-1.14; p <0.001), and 45-64 (AOR 1.67, 95% CI 1.66-1.69; p < 0.001), and Medicare in the 18-44 group (Medicare vs. private insurance: AOR 1.99, 95% CI 1.96-2.01; p <0.001). Discharges for psychiatric or substance abuse disorders, septicemia, and heart failure accounted for the largest numbers of readmissions, 5.0%, 4.7%, and 4.6% of total readmissions, with readmission rates of 24.0%, 17.9%, 22.9% respectively (Table). Total costs for readmissions were 50.7 billion USD, highest for Medicare (29.6 billion USD [58%]), with non-Medicare costs exceeding 21 billion USD (42%).
Conclusions: Costs of non-Medicare readmissions are large. Medicaid patients have the highest odds of readmission in individuals older than age 44, commonly due to hospitalizations for psychiatric illness and substance abuse disorders. Medicaid patients represent a population at uniquely high risk for readmission.