Cardiology: Patient Stroke and Bleeding Risk Determines Cost-Effectiveness of Dabigatran

For patients taking warfarin with excellent INR control, dabigatran was not cost effective

In patients with atrial fibrillation (AF) who are at medium or high risk for stroke and/or hemorrhage, dabigatran’s benefits outweigh its costs, unless international normalized ratio (INR) control with warfarin is excellent, according to a study published recently in Circulation.

Stroke prevention in patients with AF is critical and antithrombotic medications are, according to the authors of the current study, “not ideal.“ Aspirin 325 mg reduces ischemic stroke risk only by about 22 percent. Warfarin decreases stroke risk by 64 percent, but increases the risk of major bleeding by 69 percent. The Randomized Evaluation of Long Term Anticoagulation Therapy (RE-LY) study found that dabigatran etexilate 110 mg twice daily was non-inferior to warfarin and 150 mg twice daily was superior to warfarin, but patients taking dabigatran had higher rates of dyspepsia. The authors undertook the current study because although recent studies have investigated alternatives to warfarin for stroke prophylaxis in patients with AF, the cost-effectiveness of the optional medications was unknown. They thus compared the projected quality-adjusted survival and costs of alternative treatment strategies for AF, dabigatran 110 mg or 150 mg twice daily, warfarin, dual therapy with aspirin and clopidogrel, aspirin alone, or no antithrombotic.

Using the results from RE-LY and other studies, the researchers developed a decision-analysis model to compare the various antithrombotic therapies. The authors based their analysis on a hypothetical cohort of 70-year-old patients with AF using a cost-effectiveness threshold of $50,000 per quality-adjusted life-year (QALY). The annual cost of dabigatran therapy was $3,240 versus $545 for warfarin, which included INR testing and office visits. Dabigatran 150 mg twice daily was associated with a quality-adjusted survival of 8.65 QALYs; for dabigatran 110 mg twice daily it was 8.54 QAYLs; and for warfarin it was 8.40 QALYs. For patients with AF and an average risk of major hemorrhage (approximately 3 percent per year), the most cost-effective antithrombotic therapy depended on stroke risk. For patients with the lowest stroke risk (CHADS₂ score of 0), only aspirin was cost effective. For patients with moderate stroke risk (CHADS₂ of 1 to 2), warfarin was cost effective. For patients at higher risk for stroke (CHADS₂ score of 3 or more), dabigatran 150 mg twice daily was cost effective. Dabigatran 150 mg twice daily was cost effective for patients with CHADS₂ of 2 only if they were at high risk of major hemorrhage (defined as more than 6 percent per year) or if they had poor INR control with warfarin. Neither dabigatran 110 mg twice daily or dual therapy with aspirin and clopidogrel was cost effective.

Source: Shah SV, Gage BF. 2011. Cost-effectiveness of dabigatran for stroke prophylaxis in atrial fibrillation. Circulation 123:2562-2570.