Aspirin for prevention of the venous thromboembolism: a meta-analysis

Objective To systematically review the efficacy and safety of aspirin in prevention of venous thromboembolism (VTE) compared to LMWH, warfarin, rivaroxaban and placebo. Methods Randomized controlled trials (RCT) and cohort studies comparing aspirin to LMWH, warfarin, rivaroxaban and placebo for prevention of VTE were retrieved from PubMed, Embase, Cochrane Library, Scopus, Ovid, CINAHL and Wanfang Data. Meta-analysis was performed by using Rev Man 5.3 software after data extraction and quality evaluation. Results Totally 40 studies were included. There were no significant differences in overall rate of VTE (RR=1.08, 95%CI: 0.97-1.20, P=0.15) , major bleeding incidence (RR=0.97, 95%CI: 0.81-1.16, P=0.73) and death (RR=0.86, 95%CI: 0.71-1.03, P=0.10) between aspirin and LMWH groups. Aspirin was associated with a lower risk of VTE (RR=0.49, 95%CI: 0.43-0.57, P<0.05) , major bleeding (RR=0.62, 95%CI: 0.46-0.84, P<0.01) and death (RR=0.32, 95%CI: 0.15-0.64, P<0.01) compared with warfarin. Rivaroxaban was associated with a significantly lower risk of deep-vein thrombosis (DVT) (RR=2.55, 95%CI: 1.41-4.62, P<0.01) , while no significant differences in pulmonary embolism (PE) (RR=1.86, 95%CI: 0.69-5.04, P=0.22) , major bleeding (RR=0.90, 95%CI: 0.44-1.87, P=0.79) and death (RR=1.50, 95%CI: 0.60-3.74, P=0.39) compared with aspirin. Compared to placebo group aspirin significantly reduced the risk for VTE (RR=0.81, 95%CI: 0.72-0.90, P<0.01) , increased the frequency of major bleeding (RR=1.17, 95%CI: 1.06-1.30, P<0.01) , while there was no significant difference in death between aspirin and placebo (RR=0.97, 95%CI: 0.89-1.04, P=0.38) . Conclusion Aspirin is not inferior to LMWH, warfarin, and rivaroxaban in safety and efficiency for preventing VTE, and can be used for VTE prevention for patients after total joint arthroplasty. Key words: Venous thromboembolism; Aspirin; Prevention; Major bleeding; All-cause mortality; Meta-analysis