Medication adherence mediates the relationship between marital status and cardiac event-free survival in patients with heart failure

Objective: Prognosis is worse in unmarried patients compared with married patients with heart failure (HF). The reasons for differences in outcomes are unclear, but variations in medication adherence may play a role, because medication adherence is essential to achieving better outcomes. The study objective was to determine whether medication adherence mediated the relationship between marital status and cardiac event-free survival in patients with HF. Methods: Demographic, clinical, and psychosocial data were collected by questionnaires and medical record review for 136 patients with HF (aged 61 ± 11 years, 70% were male, 60% were in New York Heart Association class III/IV). Medication adherence was monitored objectively for 3 months using the Medication Event Monitoring System. Cardiac event-free survival data were obtained by patient/family interview, hospital database, and death certificate review. A series of regression and Cox survival analyses were performed to determine whether medication adherence mediated the relationship between marital status and event-free survival. Results: Cardiac event-free survival was worse in unmarried patients than in married patients. Unmarried patients were more likely to be nonadherent and 2 times more likely to experience an event than married patients (P = .017). Marital status was not a significant predictor of event-free survival after entering medication adherence in the model, demonstrating a mediation effect of adherence on the relationship of marital status to survival. Conclusion: Medication adherence mediated the relationship between marital status and event-free survival. It is important to design interventions to increase medication adherence that take into account subgroups, such as unmarried patients, who are at higher risk for nonadherence.