Newly FDA-Approved Dabigatran May Be Cost-Effective Alternative to Warfarin for Patients at Increased Risk of Stroke
BACKGROUND:
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.
FINDINGS:
- 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.
LIMITATIONS:
- 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.
AUTHOR/FUNDING INFORMATION:
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.
