Primary prophylaxis for venous thromboembolism in ambulatory cancer patients: a systematic review and network meta-analysis

BACKGROUND Ambulatory cancer patients carry a high risk of venous thromboembolism (VTE). However, the optimal prophylaxis strategy remains controversial. This meta-analysis compared the effectiveness and safety of apixaban, rivaroxaban, low molecular weight heparin (LMWH), semuloparin, aspirin, and warfarin for the prevention of VTE in ambulatory cancer patients. METHODS A systematic review and network meta-analysis was performed. PubMed, the Cochrane Central Register of Controlled Trails (CENTRAL) and EMBASE electronic databases were searched from inception to 26 April 2019. In the meta-analysis, 19 randomized controlled trials (RCTs) in ambulatory cancer patients administrated venous thromboprophylaxis agents were included. The primary outcome was the risk of VTE. Safety outcomes included the occurrence of major-bleeding. Two investigators identified the studies and performed data extraction. A network meta-analysis was performed and agents were ranked using cumulative ranking (SUCRA) probabilities. RESULTS We identified 19 studies, including 11,430 patients comparing 10 interventions. Compared to placebo controls, apixaban (5 mg) showed the highest efficacy for the prevention of VTE [odds ratio (OR) 0.36, 95% confidence interval (CI): 0.18-0.71, SUCRA=69.5] and was more effective than LMWH (OR 0.5, 0.39-0.63; SUCRA=52.1) or warfarin (OR 0.75, 95% CI: 0.35-1.59; SUCRA=25.6). Moreover, the safety of apixaban (5 mg) (OR 1.41, 95% CI: 0.33-5.93; SUCRA=58.5) was higher than LMWH (OR 1.96, 95% CI: 0.99-3.86; SUCRA=44.1) or warfarin (OR 3.06, 95% CI: 1.03-9.08; SUCRA=29.1). There were no significant differences between placebo and experimental groups in terms of patient deaths. CONCLUSIONS Anticoagulation therapies in ambulatory cancer patients can significantly reduce the risk of VTE. However, this protective effect was associated with a significantly increased risk of major bleeding. Apixaban at the appropriate dose can decrease the risk of VTE without increasing the bleeding risk. These findings require validation in larger study cohorts.