Cost-effectiveness of warfarin: Trial versus "real-world" stroke prevention in atrial fibrillation

Background and Purpose Previous cost-effectiveness analyses analyzed warfarin for stroke prevention in randomized trial settings. Given the complexities of warfarin treatment, cost-effectiveness should be examined within a real-world setting. Methods Our model followed patients with atrial fibrillation at moderate to high risk of stroke through primary and recurrent ischemic stroke, hemorrhages-intracranial and extracranial, and the resulting disability. Four scenarios were examined: (1) all patients start on warfarin with perfect control, that is, international normalized ratio (INR) values always within range; (2) all patients start on warfarin with trial-like control, where INR can fall outside the recommended range; (3) all patients start on warfarin with real-world INR control; and (4) real-world prescription (and control) of warfarin, aspirin, or neither for warfarin-eligible patients. Reported warfarin discontinuation rates were used. Main outcomes were total number of events, quality adjusted life years, and costs in a US setting. Results The total number of primary and recurrent ischemic strokes in a 1000-patient cohort (age 70 years, lifetime analysis) was 626, 832, 984, and 1,171 in scenarios 1 to 4, respectively. The corresponding mean quality adjusted life years per patient were 7.21, 6.92, 6.75, and 6.67 for scenarios 1 to 4, respectively. Costs per patient were $68,039, $77,764, $84,518, and $87,248 in scenarios 1 to 4, respectively. If "perfect" adherence to warfarin was assumed, except for discontinuations for clinical reasons, strokes would decrease to 503, 737, 909, and 1,120 in scenarios 1 to 4, respectively. Conclusions Clinical and cost outcomes are strongly dependent on the quality of anticoagulation and rates of warfarin discontinuation. Clinicians should work to improve both. Policy makers should use real-world INR control and warfarin discontinuation rates when assessing cost-effectiveness. (Am Heart J 2009; 157:1064-73.)