Newly FDA-Approved Dabigatran May Be Cost-Effective Alternative to Warfarin for Patients at Increased Risk of Stroke
Atrial fibrillation (AF) is the second most common cardiovascular condition in the U.S. – and the second most common condition affecting Veterans. AF also increases the risk of ischemic stroke by five-fold. Research shows that anticoagulation therapy with warfarin and other vitamin K antagonists can reduce the relative risk of stroke in AF by two-thirds. However, warfarin has a narrow therapeutic window and patients require frequent blood testing; warfarin also increases the risk of hemorrhage. Dabigatran – a newer anticoagulant and the first such drug approved by the FDA in 20 years – produces similar or reduced rates of ischemic stroke and hemorrhage compared with warfarin and requires no blood testing. This study evaluated the quality-adjusted survival, costs, and cost-effectiveness of dabigatran compared with warfarin for the prevention of ischemic stroke in patients >65 years with non-valvular AF. Using a Markov model, investigators performed an analysis that compared three treatment strategies in a hypothetical cohort of 10,000 patients with AF. The three strategies were: adjusted-dose warfarin, twice-daily dabigatran at low dose (110 mg), and twice-daily dabigatran at high dose (150 mg). Patient outcomes in the model included: healthy with AF, transient ischemic attack, ischemic stroke, hemorrhage, myocardial infarction, recurrent or combined events, and death. Costs were calculated over 35 years using 2008 dollars.
- In patients 65 years of age and older with non-valvular AF who are at increased risk of stroke, dabigatran could be a cost-effective alternative to adjusted dose warfarin.
- High-dose dabigatran was the most effective and the most cost-effective therapy examined.
- The quality-adjusted life expectancy was 10.28 quality-adjusted life years (QALYs) with warfarin, 10.70 QALYs with low-dose dabigatran, and 10.84 QALYs with high-dose dabigatran. Thus, high-dose dabigatran yielded an additional half a year of quality-adjusted life compared to warfarin.
- With dabigatran given at 150 mg twice daily – the approved dosage for most patients – the incremental cost compared with using warfarin is under the conventional cost-effectiveness threshold of $50,000 per QALY gained.
- Total costs were $143,193 for warfarin, $164,576 for low-dose dabigatran, and $168,398 for high-dose dabigatran.
- The cost-effectiveness of dabigatran was sensitive to the cost of the drug.
- Treatment efficacies and adverse events were largely derived from one randomized clinical trial.
- Treatments in clinical practice may not be as effective as in randomized trials, which generally enroll healthier patients, achieve higher levels of adherence, and monitor patients more intensively.
This study was funded by VA and the American Heart Association. Dr. Turakhia was supported by an HSR&D Career Development Award.
Freeman J, Zhu R, Owens D, Garber A, Hutton D, Go A, Wang P, and Turakhia M. Cost-effectiveness of Dabigatran Compared with Warfarin for Stroke Prevention in Atrial Fibrillation. Annals of Internal Medicine 2011 Jan 4;154(1):1-11.