OBJECTIVES : The effectiveness of apixaban, a novel anticoagulant that may simplify venous-thromboembolism (VTE) treatment, was observed in randomized clinical trials but evidence from real-world data is limited. The aim of this study is to assess the effectiveness of apixaban compared to warfarin for the prevention of recurrent-VTE and cardiovascular-diseases (CVD) in patients with VTE.

METHODS : A retrospective cohort analysis using Truven Marketscan database was conducted for patients who had a diagnosis of VTE or pulmonary embolism from January-2014 to December-2015. Patients who newly initiated apixaban or warfarin who had at least 12 months of continuous enrollment were included. The study outcomes including recurrent-VTE and CVD (non-fatal myocardial-infarction, and non-fatal stroke) were compared between apixaban and warfarin. Follow-up continued until the occurrence of the first event, switch to the comparator, end of enrollment or December-2015. Differences in baseline characteristics were adjusted using propensity score matching (PSM). Cox-proportional hazard model after PSM was used to obtain the hazard-ratio (HR) and 95% confidence-interval (CI).

RESULTS : After PSM, 2768 new-users of apixaban (mean-age: 63 years, 49% male, 33% baseline-CVD), and 2768 new-users of warfarin (mean-age: 63 years, 47% male, 33% baseline-CVD) who had a diagnosis of VTE were identified. The incidence rates of CVD were 33, and 62 per 1000 person-years in the apixaban and the warfarin groups, respectively. After adjustment, a 26% reduction in the risk of CVD was observed in the apixaban group compared to warfarin (HR:0.74, 95%CI[0.57, 0.95]). However, the study found no statistically significant difference in the risk of recurrent-VTE between apixaban and warfarin (HR:0.89, 95%CI[0.78, 1.01]). Results remained consistent in sensitivity analyses.

CONCLUSIONS Despite providing similar effectiveness in reducing the rate of recurrent-VTE, apixaban was associated with a reduction in non-fatal CVD events compared to warfarin in patients with VTE. Large post-marketing studies are warranted to confirm these results.