Dabigatran may be cost-effective alternative to warfarin in older patients with atrial fibrillation

Freeman JV. Ann Intern Med. 2010 Nov 1.

A high-dose formulation of dabigatran was linked to an increase of more than half a quality-adjusted life year compared with warfarin in older patients with nonvalvular atrial fibrillation, according to study results.

Researchers from several US sites created a Markov decision model to estimate the quality-adjusted survival, costs and cost-effectiveness of dabigatran (Pradaxa, Boehringer Ingelheim) compared with adjusted-dose warfarin for preventing ischemic stroke. The model was used to evaluate three treatment regimens: warfarin anticoagulation with target international normalized ratio of 2.0 to 3.0; low-dose dabigatran (110 mg twice daily); and high-dose dabigatran (150 mg twice daily).

Eligible patients were 65 years or older and had nonvalvular atrial fibrillation, demonstrated risk factors for stroke — which the researchers defined as having a CHADS2 score of at least 1 or equivalent — and had no contraindications to anticoagulation. Costs were estimated on pricing based in the United Kingdom.

Data were collected from several studies on anticoagulation, including the Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) trial.

The primary outcome measures included quality-adjusted life years (QALYs), cost in US dollars based on 2008 conversion rates and incremental cost-effectiveness ratios.

Results indicated that the quality-adjusted life expectancy was 10.28 QALYs in the warfarin arm, 10.70 QALYs in the low-dose dabigatran arm and 10.84 QALYs in the high-dose dabigatran arm.

Total costs associated with the treatments were $143,193 for warfarin, $164,576 for low-dose dabigatran and $168,398 for high-dose dabigatran, according to the results. Compared with warfarin, the incremental cost-effectiveness ratio was $51,229 per QALY for low-dose dabigatran and $45,372 per QALY for high-dose dabigatran.

A sensitivity analysis was conducted that adjusted for variables, including drug cost, stroke, intracranial hemorrhage risk for dabigatran and warfarin, age, utility of dabigatran and warfarin, costs after intracranial hemorrhage and utility after myocardial infarction. Results indicated that the incremental cost-effectiveness ratio increased to $50,000 per QALY at a cost of $13.70 per day in the high-dose dabigatran arm but remained less than $85,000 per QALY when accounting for the full range of model inputs.

“High-dose dabigatran was the most cost-effective and most effective therapy we evaluated, providing an additional 0.56 QALY over warfarin in our base-case analysis,” the researchers wrote. They noted that dabigatran was incrementally cost-effective in patients at risk for stroke and intracranial hemorrhage.

“These results were robust over a wide range of model assumptions but were sensitive to dabigatran costs,” they wrote.

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