Changes in adherence to evidence-based medications in the first year after initial hospitalization for heart failure: observational cohort study from 1994 to 2003

Abstract

Background: The use of evidence-based medications in patients with heart failure has increased over the past 10 years. We aimed to determine whether adherence to these medications has also increased during this time.

Methods and results: A retrospective cohort was created using administrative databases from the province of Saskatchewan, Canada. Subjects discharged alive from their first hospitalization for heart failure between 1994 and 2003 were eligible. Those filling a prescription for a beta-blocker (BB), angiotensin-converting enzyme inhibitor (ACEI), or angiotensin receptor blocker (ARB) within 6 months of discharge were followed for 1 year after the initial prescription. Of 8805 eligible patients, 67% of BB users (941/1414) and 74% of ACEI/ARB users (4441/5991) exhibited optimal adherence at 1 year (defined as >or=80% adherence calculated from pharmacy refill records). When grouped by year of initial heart failure hospitalization, the proportion of optimally adherent patients improved from 54% to 75% with BB and from 67% to 80% with ACEI/ARBs between 1994/1995 and 2002/2003 (P for trend <0.001 for both). Mean 1-year adherence improved from 71% to 83% for BB and 80% to 88% for ACEI/ARBs. After adjustment using multivariable logistic regression, subjects discharged in 2003 were significantly more likely to exhibit optimal adherence to a BB (odds ratio, 2.04; 95% CI, 1.21 to 3.44) or an ACEI/ARB (odds ratio, 1.65; 95% CI, 1.30 to 2.08) than those prescribed therapy in 1994/1995.

Conclusions: One-year adherence to BB and ACEI/ARB is improving over time in patients discharged after first heart failure hospitalization. Patients taking multiple cardiac medications were not any less likely to exhibit optimal adherence than patients taking only 1 medication.