Objectives: To examine the relationship between 6-month medication adherence and 1-year downstream heart disease-related readmission among patients who survived a myocardial infarction (MI).
Study design: Retrospective, nested case-control analysis of Medicare fee-for-service beneficiaries who were discharged alive post MI in 2008 (n = 168,882).
Methods: Patients in the case group had their first heart-disease-related readmission post MI discharge during the 6-to-9-month period or the 9-to-12-month period. We then used propensity score matching to identify patients in the control group who had similar characteristics, but did not have a readmission in the same time window. Adherence was defined as the average 6-month medication possession ratio (MPR) prior to the first date of the time-window defining readmission.
Results: After controlling for demographics, insurance coverage, and clinical characteristics, patients who had a heart-disease-related readmission had worse adherence, with MPRs of 0.70 and 0.74 in the case and control groups, respectively. Odds ratio of MPR ≥ 0.75 was 0.79 (95% CI, 0.75-0.83) among those with a readmission relative to those without.
Conclusions: Our study shows that better 6-month medication adherence may reduce heart-disease-related readmissions within a year after an MI.