COST-EFFECTIVENESS OF DABIGATRAN COMPARED WITH WARFARIN FOR STROKE PREVENTION IN ATRIAL FIBRILLATION

Title: Cost-Effectiveness of Dabigatran Compared With Warfarin for Stroke Prevention in Atrial Fibrillation
Date Posted: January 14, 2011
Authors: Freeman JV, Zhu RP, Owens DK, et al.
Citation: Ann Intern Med 2011;154:1-11.

Study Question:
What is 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 atrial fibrillation (AF)?

Methods:
The study used a Markov decision model using 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. The study population consisted of patients ages 65 years or older with nonvalvular AF and risk factors for stroke (CHADS2 score ≥1 or equivalent) and no contraindications to anticoagulation. A lifetime societal perspective was used for the cost-effectiveness analysis. Warfarin anticoagulation (target international normalized ratio, 2.0-3.0) was compared with dabigatran 110 mg twice daily (low dose) and dabigatran 150 mg twice daily (high dose), and quality-adjusted life-years (QALYs), costs (in 2008 U.S. dollars), and incremental cost-effectiveness ratios were analyzed.

Results:
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. 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.

Conclusions:
The authors concluded that in patients ages 65 years or older with nonvalvular AF at increased risk for stroke, dabigatran may be a cost-effective alternative to warfarin.

Perspective:
The study suggests that in patients ages 65 years or older with AF who are at increased risk for stroke (CHADS2 score ≥1 or equivalent), dabigatran could be a cost-effective alternative to warfarin. The base-case analysis estimated a cost of $45,372 per QALY gained with high-dose dabigatran compared with warfarin, which was within a range generally considered to be cost-effective. The cost-effectiveness of dabigatran was sensitive to drug costs and relative differences in cost between the high- and low-dose formulations. In addition, for patients at higher risk for ischemic stroke or intracranial hemorrhage, including those with CHADS2 scores of 2 or greater, the cost-effectiveness for high-dose dabigatran compared with warfarin improved. The results of this analysis were derived from a single clinical trial and could change if future effectiveness studies provide alternative estimates for bleeding risk and stroke reduction.

POSTED BY STEVEN ALMANY, MD