Adherence to Disease-Modifying Therapy in Patients Hospitalized for HF: Findings from a Community-Based Study

Background: Much data about prescription adherence in patients with heart failure (HF) are available, but few exist about the evaluation of true patient adherence. Further, methods for analyzing this issue are poorly known. Objectives: Our objective was to evaluate the impact of patient adherence to disease-modifying drugs after HF hospitalization in a community-based cohort. Methods and Results: Patients hospitalized with first diagnostic HF code and at least one post-discharge purchase of evidence-based drugs for HF between 2009 and 2015 were included (12,938 patients). A new method for measuring adherence to polypharmacy (patient adherence indicator [PAI]) was introduced, based on proportion of days covered (PDC) and medication possession ratio (MPR). The investigated drugs were β-blockers (BBs), angiotensin-converting enzyme inhibitors (ACEIs), angiotensin-receptor blockers (ARBs), and anti-aldosterone agents (AAs). Regional administrative databases were analyzed. Results: The mean age of the cohort was 80 years; 53% was female; the median Charlson Comorbidity Index score was 2, and the overall death rate was 60%. PAI based on PDC estimated a nonadherence rate of 47%. Median daily dosages were well below target dosages for all drugs considered. A good PAI significantly lowered the mortality risk, irrespective of the computational method used: PDC (PAI adjusted hazard ratio [HR] 0.93; 95% confidence interval [CI] 0.88–0.97; p = 0.001) or MPR (PAI adjusted HR 0.93; 95% CI 0.89–0.98; p = 0.004). Conclusions: In a real-world setting, medication adherence of patients with HF remains unsatisfactory, especially when in a polypharmacy setting. Irrespective of PDC and MPR, good patient adherence to polypharmacy was associated with a lower death rate.