Abstract 16789: Adherence to Medications for Atrial Fibrillation

Abstract

Background: Atrial fibrillation (AF) is an emerging epidemic, primarily managed pharmacologically with complex medication regimens. Even if AF medications are prescribed according to evidence and guidelines, patients do not receive the full benefit of therapies if they do not take them as intended. We conducted a population-based study using administrative data to evaluate patient adherence to AF medications in a large integrated healthcare system in Ontario, Canada.

Methods: Using hospital discharge, prescription claims and vital statistics databases, we estimated adherence with current AF therapies in patients 65 years and older who were hospitalized for a primary or secondary diagnosis of AF between January 1, 1998 and March 31, 2012. Adherence was measured as the mean medication possession ratio (MPR)+/-SD at one year following initiation of therapy for the following medication classes: antiarrhythmics (AAs [class III AA agents: amiodarone, sotalol, and class I AA agents]), rate control agents (RCA [beta-blockers, calcium channel blockers, digoxin]) and antithrombotics (ATs [warfarin, ASA, clopidogrel]).

Results: In 169,525 patients with AF who survived the first year, there were 48,654 index prescriptions for AAs, 219,072 for RCAs, and 163,389 for ATs, primarily warfarin (122,947). Within AAs, adherence was highest with sotalol at an MPR of 0.78+/-0.38, closely followed by amiodarone at 0.76+/-0.36, and lowest with class I AAs at 0.72+/-0.40. Within RCAs, adherence was highest with beta-blockers at an MPR of 0.88+/-0.50, followed closely by calcium channel blockers at 0.86+/-0.38 and digoxin at 0.86+/-0.36. Within ATs, adherence with warfarin was high with an MPR of 0.94+/-0.50.

Conclusion: Adherence with RCAs is higher than with AAs. Patients have a high level of adherence (>80%) to warfarin and RCAs, while adherence to AAs on average is below 80%. Prescriptions for AAs are filled by patients at a lower level than may be optimal to benefit from a rhythm control strategy.