increased benefit of betrixaban among patients with a history of venous thromboembolism: a post-hoc analysis of the apex trial

Hospitalized acute medically ill patients with a history of venous thromboembolism (vte) are at increased risk for recurrent vte. we characterized the efficacy and safety of betrixaban for prevention of recurrent vte in these high risk patients. the apex trial randomized 7513 acutely ill hospitalized medical patients at risk for developing vte to receive either betrixaban for 35–42 days or enoxaparin for 10 ± 4 days to prevent vte. this exploratory post-hoc analysis assessed the efficacy and safety of betrixaban versus enoxaparin among subjects with and without prior vte. time-to-multiple symptomatic vte events was also calculated. approximately 8% of subjects in both arms had prior vte, which was associated with a fourfold increase in adjusted risk of vte [mv or 4.03, 95% ci 3.06–5.30, p < 0.001]. betrixaban reduced vte compared with enoxaparin among subjects with prior vte [32 (10.4%) vs. 55 (18.9%), rr 0.57, 95% ci 0.38–0.86, p = 0.006, arr 8.5%, nnt 12] and without prior vte [133 (3.9%) vs. 168 (4.9%), rr 0.79, 95% ci 0.64–0.99, p = 0.042, arr 1.0%, nnt 100] (interaction p > 0.05). additionally, four subjects in the enoxaparin arm and one subject in the betrixaban arm experienced a recurrent vte. compared with enoxaparin, betrixaban use was associated with reduction of recurrent vte events through the active treatment period [36 vs. 57, hr 0.63, 95% ci 0.41–0.97, p = 0.045] and through the end of study [38 vs. 71, hr 0.54, 95% ci 0.36–0.81, p = 0.004]. prior vte is associated with a fourfold increase in the risk of vte among hospitalized medically ill patients. only 12 such patients would need to be treated with betrixaban versus enoxaparin to prevent an additional vte endpoint. betrixaban reduced not only the first but also all recurrent vte events in a time-to-any-event analysis. trial registration: http://www.clinicaltrials.gov , unique identifier: nct01583218