Health-Related Quality of Life Is a Mediator of the Relationship Between Medication Adherence and Cardiac Event-Free Survival in Patients with Heart Failure

Background: Health-related quality of life (HRQOL) is an important patient-reported outcome that is related to medication adherence, hospitalization and death. The nature of the relationships among medication adherence, HRQOL, and hospitalization and death is unknown. We sought to determine the relationships among medication adherence, HRQOL, and cardiac event-free survival in patients with heart failure. Methods and Results: We enrolled 218 patients with heart failure. Patients' medication adherence was measured objectively using the Medication Event Monitoring System. HRQOL was assessed using the Minnesota Living with Heart Failure Questionnaire. Patients were followed for up to 3.5 years to collect hospitalization and mortality data. Mediation analysis was used to determine the nature of the relationships among the variables. Patients with better medication adherence had better HRQOL (P = .014). Medication adherence and HRQOL were associated with cardiac event-free survival (both P < .05). Patients with medication nonadherence were 1.86 times more likely to experience a cardiac event than those with better medication adherence (P = .038). Medication adherence was not associated with cardiac event-free survival after entering HRQOL in the model (P = .118), indicating mediation by HRQOL of the relationship between medication adherence and cardiac event-free survival. Conclusions: HRQOL mediated the relationship between medication adherence and cardiac event-free survival. It is important to assess medication adherence and HRQOL regularly and develop interventions to improve medication adherence and HRQOL to decrease hospitalization and mortality in patients with heart failure.