COST-EFFECTIVENESS OF WARFARIN AND DABIGATRAN TO PREVENT STROKE IN ELDERLY MALE PATIENTS WITH ATRIAL FIBRILLATION

Purpose: To determine the cost-effectiveness of warfarin and dabigatran in a cohort of 85-year-old male patients with atrial fibrillation (AF).

Method: We developed a four state Markov model with a cycle length of 3 months to project costs and quality-adjusted life-years (QALYs) of warfarin and dabigatran treatment over the life span of a hypothetical cohort of male patients aged 85 years with AF. All model estimates were derived from a clinical trial (RE-LY trial) and an observational study. Costs were evaluated from a Medicare perspective. To evaluate the costs and benefits of each strategy, we conducted an incremental cost-effectiveness analysis. To test for uncertainty in the model estimates, we performed deterministic sensitivity analyses on all parameters, and threshold analyses on costs.

Result: We found that dabigatran was more costly but also slightly more effective than warfarin, with an incremental cost-effectiveness of $407,336 per QALY. One-way and two-way sensitivity analyses showed that our results were robust. When willingness to pay was $50,000 per QALY, warfarin had the highest probability of being cost-effective (99%). Only when the willingness-to-pay threshold exceeded $500,000 per QALY, did dabigatran have a higher probability of being cost-effective than warfarin. Threshold analyses showed that dabigatran would be cost-effective at a price of $120.

Conclusion: Our analysis indicates that warfarin is a much more affordable drug therapy compared to dabigatran. This study adds substantial information to the existing literature on the cost-effectiveness of warfarin and dabigatran. Of note, our analysis involved a cohort of older adults, which has not been modeled previously. Additionally, our analysis is based on the most up to date data available on AF patients and utilizes data from multiple sources (clinical and observational data). No study that we know of has used this data to inform their Markov model before. Our main objective was to compare warfarin to dabigatran, yet several other blood thinners are available, including apixaban and rivaroxaban. Future cost-effectiveness analyses should consider additional blood thinners.