Adherence and persistence in the use of warfarin after hospital discharge among patients with heart failure and atrial fibrillation

Background Postdischarge adherence and long-term persistence in the use of warfarin among patients with heart failure and atrial fibrillation without contraindications have not been fully described. Methods and Results We identified patients with heart failure and atrial fibrillation who were ≥65 years old, eligible for warfarin, and discharged home from hospitals in the Get With the Guidelines-Heart Failure registry from January 1, 2006, to December 31, 2009. We used linked Medicare prescription drug event data to measure adherence and persistence. The main outcome measures were rates of prescription at discharge, outpatient dispensing, discontinuation, and adherence as measured by the medication possession ratio. We hypothesized that adherence to warfarin would differ according to whether patients received the prescription at discharge. Among 2,691 eligible patients, 1,856 (69.0%) were prescribed warfarin at discharge. Patients prescribed warfarin at discharge had significantly higher prescription fill rates within 90 days (84.5% vs 12.3%; P <.001) and 1 year (91.6% vs 16.8%; P <.001) and significantly higher medication possession ratios (0.78 vs 0.63; P <.001). Among both previous nonusers and existing users, fill rates at 90 days and 1 year and possession ratios were significantly higher among those prescribed warfarin at discharge. Conclusions One-third of eligible patients with heart failure and atrial fibrillation were not prescribed warfarin at discharge from a heart failure hospitalization, and few started therapy as outpatients. In contrast, most patients who were prescribed warfarin at discharge filled the prescription within 90 days and remained on therapy at 1 year.