Medication Adherence Mediates the Relationship between Heart Failure Symptoms and Cardiac Event-Free Survival in Patients with Heart Failure

Background: Heart failure (HF) symptoms such as dyspnea are common and may precipitate hospitalization. Medication nonadherence is presumed to be associated with symptom exacerbations, yet how HF symptoms, medication adherence, and hospitalization/death are related remains unclear. Objective: The aim of this study was to explore the relationships among HF symptoms, medication adherence, and cardiac event-free survival in patients with HF. Methods: At baseline, patient demographics, clinical data, and HF symptoms were collected in 219 patients with HF. Medication adherence was monitored using the Medication Event Monitoring System. Patients were followed for up to 3.5 years to collect hospitalization and survival data. Logistic regression and survival analyses were used for the analyses. Results: Patients reporting dyspnea or ankle swelling were more likely to have poor medication adherence (P =.05). Poor medication adherence was associated with worse cardiac event-free survival (P =.006). In Cox regression, patients with HF symptoms had 2 times greater risk for a cardiac event than patients without HF symptoms (P =.042). Heart failure symptoms were not a significant predictor of cardiac event-free survival after entering medication adherence in the model (P =.091), indicating mediation. Conclusions: Medication adherence was associated with fewer HF symptoms and lower rates of hospitalization and death. It is important to develop interventions to improve medication adherence that may reduce HF symptoms and high hospitalization and mortality in patients with HF.