Persistence With Therapy Among Patients Treated With Warfarin for Atrial Fibrillation
What is the rate of persistence with warfarin therapy in a large population-based cohort of newly treated patients with atrial fibrillation (AF)?
The investigators conducted a population-based cohort study among residents of Ontario, Canada, 66 years and older, who commenced treatment with warfarin between April 1, 1997, and March 31, 2008. The authors constructed Kaplan-Meier curves to characterize drug therapy discontinuation. Secondary analyses described persistence with warfarin therapy according to age (66-75 years, 76-85 years, and ≥86 years), sex, CHADS2 (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, and prior stroke or transient ischemic attack) score, and date of warfarin therapy initiation. The log-rank test was used to examine differences in persistence among patient subgroups.
Of 125,195 patients who started warfarin therapy for AF, 8.9% did not fill a second warfarin prescription during follow-up, 31.8% discontinued therapy within 1 year, 43.2% discontinued therapy within 2 years, and 61.3% discontinued therapy within 5 years. The median time to discontinuation (MTD) was 2.9 years. Men discontinued warfarin therapy earlier than women, whereas patients ages 66-75 years were more likely to discontinue therapy compared with older patient groups. Persistence with warfarin therapy increased with stroke risk, as reflected by the CHADS2 score.
The authors concluded that patients who have had large-vessel occlusion strokes, but are ineligible for (or refractory to) intravenous tissue plasminogen activator, should be treated with the Trevo Retriever in preference to the Merci Retriever.
This study reports that persistence with warfarin therapy among older patients with AF is lower than generally appreciated and that male sex, younger age, and lower stroke risk predicted poorer persistence with drug therapy. These findings highlight the importance of considering recent real-world estimates of warfarin therapy compliance, when comparing warfarin with newer anticoagulants that also carry a risk of hemorrhage yet require no routine monitoring. For warfarin or any of the newer anticoagulants, the importance of appropriate patient education and periodic reinforcement by the treating physician cannot be overemphasized.
Keywords: Stroke, Ischemic Attack, Transient, Follow-Up Studies, Warfarin, Canada, Ontario, Brain Ischemia, Heart Failure, Tissue Plasminogen Activator, Hypertension, Diabetes Mellitus, Hemorrhage
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