Abstract 16741: The Cost-Effectiveness of Apixaban versus Warfarin in Patients With Atrial Fibrillation: Insights From the ARISTOTLE Study Group

Background: In Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE), apixaban (vs. warfarin) significantly reduced stroke, death, and major bleeding in 18,201 patients with atrial fibrillation (AF). We assessed the cost-effectiveness of apixaban vs. warfarin from the perspective of the US health care system. Methods: Resource use (service dates, intensive care days, days on drug) was obtained from ARISTOTLE case report forms. Unit costs for components of hospital-based care of AF patients were estimated with generalized linear models using the national Premier database. Daily cost of anticoagulants was based on current acquisition cost (apixaban=$9.49; warfarin=$0.09) for 10 years, after which time apixaban was valued at projected costs of generic substitutes ($1.89). Physician services and anticoagulant monitoring were valued using Medicare fees. Within-trial costs were estimated using inverse probability weighting for differential follow-up. Survival was modeled with patient-level ARISTOTLE data using a two stage approach that combined a time-based Cox model for the within-trial period and an age-based Cox model for extrapolation. Uncertainty surrounding estimates of cost, life expectancy and cost/per life year gained was characterized with bootstraps and sensitivity analyses. Results: After 2 years, costs in the US cohort (n=3417) excluding study drug and monitoring averaged $306 less with apixaban than warfarin ($6257 vs. $6563). This difference was more than offset by higher apixaban anticoagulation costs ($6160 vs. $1181), resulting in an overall increase of $4673/patient. Over a lifetime, gains in life expectancy with apixaban (9.92 vs. 9.69; p<.001) were achieved at an additional cost of $17,564 ($29,447 vs. $11,883; p<.001), yielding a cost-effectiveness ratio (ICER) of $76,365/life year gained (85% likelihood of meeting $110,000 willingness to pay threshold). Cost-effectiveness was most sensitive to cost of apixaban. Conclusions: Reductions in mortality, stroke, and bleeding observed in ARISTOTLE translate to significant increases in life expectancy. At an estimated ICER of $76,365/life year gained, apixaban is a cost-effective alternative to warfarin.