Dabigatran, a fixed-dose, oral direct thrombin inhibitor, may be a cost-effective alternative to warfarin therapy in atrial fibrillation (AF) patients who are 65 years of age or older, according to a modeled analysis published in the Nov. 2 issue of the Annals of Internal Medicine.

In the analysis, James V. Freeman, MD, MPH, of the Stanford University School of Medicine in Stanford, Calif., and colleagues used a mathematical Markov model to evaluate quality-adjusted life-years (QALYs), costs and cost effectiveness of warfarin (Coumadin, Bristol-Myers Squibb/Sanofi-Aventis) or a low or high twice-daily dose of dabigatran (Pradaxa, Boehringer Ingelheim): 110 mg or 150 mg.

The model simulated a hypothetical cohort of 10,000 AF patients over the age of 65 and who were at risk for stroke. The researchers used data from the RE-LY (Randomized Evaluation of Long-Term Anticoagulation Therapy) trial and other anticoagulation studies.

According to the authors, dabigatran is not yet priced for the U.S. market but has estimated costs of $13 per day in the U.K., where the drug is approved for the prevention of venous thromboembolism—warfarin is estimated to cost just over $1 per day.

To estimate the costs of the drugs, the researchers projected costs over a 35-year period and included age-adjusted average healthcare expenditures for each payment and added costs associated with each of the three aforementioned treatment strategies: low-dose warfarin, low-dose dabigatran and high-dose dabigatran.

Freeman and colleagues found that the quality-adjusted life expectancy was 10.28 QALYs with warfarin versus 10.70 QALYs for low-dose dabigatran and 10.84 QALYs for high-dose dabigatran. Additionally, the analysis showed the total estimated costs for low-dose warfarin, low-dose dabigatran and high-dose dabigatran were $143,194, $164,576 and $169,398, respectively.

Compared with warfarin, the incremental cost-effectiveness ratios for low-dose dabigatran and high-dose dabigatran were $51,229 per QALY and $45,372 per QALY, respectively.

“Thus, at our base-case prices, high-dose dabigatran was more cost effective than low-dose dabigatran,” the authors wrote.

Freeman et al also found that the incremental cost-effectiveness ratio increased to $50,000 per QALY at a cost of $13.70 per day for high-dose dabigatran but was less than $85,000 per QALY for the full range of model inputs evaluated.

The high-dose dabigatran prevented 1,000 more intracranial hemorrhages and 600 more strokes compared to what warfarin was estimated to prevent; however, low-dose dabigatran resulted in 400 additional MIs and 400 ischemic strokes.

“Our analysis suggests that, at a willingness-to-pay threshold of $50,000 per QALY, low-dose dabigatran may be the preferred therapy for patients with a low absolute risk for ischemic stroke … especially if their concurrent risk for ICH [intracranial hemorrhage] is high,” the authors concluded. “For patients with low absolute risk for ICH, warfarin may be the preferred therapy. However, for some low-risk patients, antiplatelet therapy rather than anticoagulation may be a reasonable alternative, but further clinical study is needed to determine optimal treatment for patients who are at low risk for stroke and ICH.”

The study was funded by the American Heart Association and Veterans Affairs Health Services Research & Development Service.