Impact of medication therapy discontinuation on mortality after myocardial infarction

Background: Nonadherence to medications is common, but the determinants and consequences are poorly defined. The objectives of this study were to identify patient and myocardial infarction (MI) treatment factors associated with medication therapy discontinuation and to assess the impact of medication discontinuation 1 month after MI on 12-month mortality. Methods: This was a multicenter prospective cohort of patients with MI enrolled in the Prospective Registry Evaluating Myocardial Infarction: Event and Recovery study. The outcomes were use of aspirin, beta-blockers, and statins at 1 month after MI hospitalization among patients discharged with all 3 medications as well as 12-month mortality. Results: Of 1521 patients discharged with all 3 medications, 184 discontinued use of all 3 medications, 56 discontinued use of 2 medications, 272 discontinued use of 1 medication, and 1009 continued taking all 3 medications at 1 month. In multivariable analyses, patients not graduating from high school (odds ratio [OR], 1.76; 95% confidence interval [CI], 1.20- 2.60) were more likely to discontinue use of all medications. The effect of increasing age on medication therapy discontinuation was greater for females (OR, 1.77; 95% CI, 1.34- 2.34) than males (OR, 1.23; 95% CI, 1.02- 1.47). Patients who discontinued use of all medications at 1 month had lower 1-year survival (88.5% vs 97.7%; log-rank P <.001) compared with patients who continued to take 1 or more medication(s). In multivariable survival analysis, medication therapy discontinuation was independently associated with higher mortality (hazards ratio, 3.81; 95% CI, 1.88-7.72). Results were consistent when evaluating discontinuation of use of aspirin, beta-blockers, and statins separately. Conclusions: Medication therapy discontinuation after MI is common and occurs early after discharge. Patients who discontinue taking evidence-based medications are at increased mortality risk. These findings suggest the need to improve the transition of care from the hospital to outpatient setting to ensure that patients continue to take medications that have mortality benefit.