Abstract
Background
Clinical guidelines recommend direct oral anticoagulants over vitamin-K antagonists for treatment of venous thromboembolism (VTE); however, there are no specific recommendations for VTE treatment inpatients with thrombophilia.
Aims
5 US healthcare claims databases were used to evaluate the risk of recurrent VTE, major bleeding (MB),and clinically relevant non-major (CRNM) bleeding among VTE patients initiating apixaban or warfarin stratified by presence of thrombophilia.
Methods
Adult VTE patients initiating apixaban or warfarin were identified from CMS Medicare and four other claims databases. Stabilized inverse probability treatment weighting (IPTW) was conducted to balance characteristics between apixaban and warfarin patients. After IPTW, subgroup interaction analysis evaluated whether treatment effects were consistent across patients with and without diagnosis of thrombophilia. Statistical significance (P<0.10) of the interaction between treatment and thrombophilia was evaluated using Cox proportional hazard models.
Results
A total of 60,786 apixaban and 94,333 warfarin patients with VTE were eligible for analysis. After IPTW, all patient characteristics were balanced between treatment cohorts. Apixaban patients had significantly lower risk of recurrent VTE, MB, and CRNM bleeding compared to warfarin. When stratified by thrombophilia, apixaban showed consistently lower risk of recurrent VTE, MB, and CRNM bleeding compared to warfarin across patients with and without thrombophilia. No significant interaction was observed for recurrent VTE or MB. One significant interaction was observed for CRNM bleeding: apixaban trended towards a lower risk of CRNM bleeding compared to warfarin across both subgroups, but magnitude of effect was larger for patients with thrombophilia (Figure). The findings were consistent with those of the overall population.
Conclusions
Among subgroups of VTE patients with and without thrombophilia, apixaban patients had a lower risk of recurrent VTE, MB, and CRNM bleeding compared to warfarin patients, which was consistent with the overall population results.
