Cost-effectiveness of dabigatran compared with warfarin for stroke prevention in atrial fibrillation

Abstract

Background: Warfarin reduces the risk for ischemic stroke in patients with atrial fibrillation (AF) but increases the risk for hemorrhage. Dabigatran is a fixed-dose, oral direct thrombin inhibitor with similar or reduced rates of ischemic stroke and intracranial hemorrhage in patients with AF compared with those of warfarin.

Objective: To estimate the quality-adjusted survival, costs, and cost-effectiveness of dabigatran compared with adjusted-dose warfarin for preventing ischemic stroke in patients 65 years or older with nonvalvular AF.

Design: Markov decision model.

Data sources: The RE-LY (Randomized Evaluation of Long-Term Anticoagulation Therapy) trial and other published studies of anticoagulation. The cost of dabigatran was estimated on the basis of pricing in the United Kingdom.

Target population: Patients aged 65 years or older with nonvalvular AF and risk factors for stroke (CHADS₂ score ≥1 or equivalent) and no contraindications to anticoagulation.

Time horizon: Lifetime.

Perspective: Societal.

Intervention: Warfarin anticoagulation (target international normalized ratio, 2.0 to 3.0); dabigatran, 110 mg twice daily (low dose); and dabigatran, 150 mg twice daily (high dose).

Outcome measures: Quality-adjusted life-years (QALYs), costs (in 2008 U.S. dollars), and incremental cost-effectiveness ratios.

Results of base-case analysis: The quality-adjusted life expectancy was 10.28 QALYs with warfarin, 10.70 QALYs with low-dose dabigatran, and 10.84 QALYs with high-dose dabigatran. Total costs were $143 193 for warfarin, $164 576 for low-dose dabigatran, and $168 398 for high-dose dabigatran. The incremental cost-effectiveness ratios compared with warfarin were $51 229 per QALY for low-dose dabigatran and $45 372 per QALY for high-dose dabigatran.

Results of sensitivity analysis: The model was sensitive to the cost of dabigatran but was relatively insensitive to other model inputs. The incremental cost-effectiveness ratio increased to $50 000 per QALY at a cost of $13.70 per day for high-dose dabigatran but remained less than $85 000 per QALY over the full range of model inputs evaluated. The cost-effectiveness of high-dose dabigatran improved with increasing risk for stroke and intracranial hemorrhage.

Limitation: Event rates were largely derived from a single randomized clinical trial and extrapolated to a 35-year time frame from clinical trials with approximately 2-year follow-up.

Conclusion: In patients aged 65 years or older with nonvalvular AF at increased risk for stroke (CHADS₂ score ≥1 or equivalent), dabigatran may be a cost-effective alternative to warfarin depending on pricing in the United States.

Primary funding source: American Heart Association and Veterans Affairs Health Services Research & Development Service.