Objective: To investigate potential determinants of long-term adherence to evidence-based cardioprotective medications (EBCMs) of aspirin, β-blockers, ACEIs/ARBs, and statins in patients with AMI, and to estimate the effect of adherence on all-cause mortality.
Methods: Patient-based retrospective cohort study of 1-year survivors of AMI, members of Leumit Health Services, between 2005 and 2010. Adherence was measured using the proportion-of-days-covered (PDC) metric, and defined as PDC≥80%.
Results: Of 4655 patients prescribed at least one medication, 864 died during an 8-year follow up (median 4.5 years). Nonadherence to each EBCM approximated 50%, and 80% for combined therapy of all EBCMs. In multivariable analyses, adherers to at least one EBCM were more likely to be of Jewish origin (adjusted odds-ratio, 2.11; 95% confidence interval, 1.60-2.78), and attending a cardiologist at least once during the first year of follow-up (1.26; 1.05-1.51). Increasing number of outpatient visits to primary physicians and cardiologists was associated with improved adherence and followed a significant dose-response gradient. Factors significantly associated with reduced adherence were presence of comorbid conditions, and readmissions within the first year of follow-up (0.65; 0.55-0.78). Results were consistent when evaluating adherence of each EBCM separately.
Except for β-blockers, medication nonadherence was significantly associated with increased all-cause mortality risk for aspirin (Adjusted hazard-ratio, 1.28; 95% confidence interval, 1.11-1.47), statins (1.36; 1.18-1.57), and ACEIs/ARBs only among IHD patients with documentd heart failure (1.57, 1.16-2.14). Multidrug combined therapy exerted incremental survival benefit in a dose-response gradient, exceeding that of single component treatment, with the highest risk of mortality observed in patients adherent to none of the EBCMs as compared to adherents to all EBCMs (1.38; 1.06-1.80).
Conclusions: Nonadherence to EBCMs in patients with AMI is common and is associated with a marked risk increase in all-cause mortality. Further research is needed to elucidate the role of ACEI/ARB in patient subgroups.
