Comparison of Readmission Rates After Acute Myocardial Infarction in 3 Patient Age Groups (18 to 44, 45 to 64, and ≥65 Years) in the United States

Abstract

Postacute myocardial infarction (AMI) readmissions are common among Medicare beneficiaries (≥65 years) and are associated with significant resource utilization. However, patterns of AMI readmissions for younger age groups in the United States are not known. In the Nationwide Readmissions Database, a nationally representative all-payer database of inpatient hospitalizations, we identified 212,171 index AMI hospitalizations in January to November 2013, weighted to represent 478,247 hospitalizations nationally (mean age 66.9 years, 38% women, 29% low income). This included 26,516 cases in the 18 to 44 age group, 183,703 in the 45 to 64 age group, and 268,027 in the ≥65 age group. The overall 30-day readmission rate was 14.5% and varied across age groups (9.7% [18 to 44], 11.2% [45 to 64], and 17.3% [≥65]). The cumulative cost of 30-day readmissions was $1.1 billion, of which $365 million was spent on those <65 years of age. In multivariable hierarchical models, the risk of readmission was higher in women and in low-income patients, but the effect varied by age (p value for age-gender and age-income interactions <0.05) and was more prominent in the younger age groups. Further, patients in all age groups continue to have a high hospitalization burden beyond the typical 30-day readmission period, with an overall 24% post-AMI 90-day readmission rate. In conclusion, readmissions in young and middle-aged AMI survivors pose a substantial burden on patients and on U.S. health-care resources. Women and low-income patients with AMI, particularly those in younger age groups, are more frequently readmitted, and readmissions continue to burden the health-care system beyond the typical 30-day window. Future investigations would need to be targeted toward a better understanding and improvement of the rehospitalization burden for vulnerable patient groups.

Figure 1

Cumulative cost of index AMI hospitalizations and 30-day readmission, overall and by age groups in the United States.

Figure 2

Risk-adjusted odds ratio for readmission in age groups by (1) gender (significant age-gender interaction, p = 0.01), and (2) income (significant age-income interaction, p = 0.007), lowest-income quartile versus highest quartile presented (other groups included in Supplementary Table S6 of Appendix S1).