Reducing the risk of venous thromboembolism using apixaban - patient perspectives and considerations. Should more attention be given to females?

BACKGROUND New oral anticoagulant agents, such as apixaban, rivaroxaban, dabigatran, or endoxaban, have recently become for patients an alternative option to conventional treatment in the therapy of venous thromboembolism (VTE). Thus, we aimed to review the available information on adverse events (AEs) of apixaban compared to conventional therapy (heparin or vitamin K antagonists) in randomized controlled trials (RCTs) on patients treated for VTE, with a particular attention to sex subgroups. METHODS An electronic search in MEDLINE and Embase was performed by using the keywords "apixaban" and "venous thromboembolism". All RCTs focused on apixaban in the treatment and prevention of VTE were evaluated for the presence of AEs. AEs were classified as serious, bleeding, and cause of discontinuation. Moreover, we also searched by using the keywords "gender" and "venous thromboembolism" and "anticoagulants". RESULTS Considering all subjects enrolled in the eleven RCTs as a whole to investigate the occurrence of AEs, we extrapolated an events/subjects rate of 57.8% for AEs (6,445/11,144), 7.7% for serious AEs (975/12,647), 9.1% for bleeding events (1,229/13,454), and 3.2% for discontinuation of apixaban (421/13,039). The percentage of AEs was lower in subjects treated with apixaban than in those treated with conventional VTE therapy (53% vs 56.3%, respectively). However, only one study provided data on separate analysis by sex of either efficacy or safety of apixaban. CONCLUSION Under the patient's perspective, apixaban could represent a good choice in the treatment of VTE, due to its pharmacological, economical, and safety profile. These positive aspects are certainly present in both sexes, since the available studies include a correct percentage of women, but data with separate analyses by sex are extremely limited. Future clinical trials should include in their results on clinical impact and outcomes a stratification by sex, and studies aimed to evaluate possible sex-related differences for these drugs should be strongly encouraged.