Aspirin for the extended prevention of venous thromboembolism: a meta-analysis and trial sequential analysis

Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), is a major complication following surgery and in high-risk scenarios. Aspirin may provide an alternative for extended VTE prophylaxis, but its risk-benefit profile remains unclear. We conducted a systematic review and meta-analysis of randomized controlled trials, following PRISMA guidelines, to evaluate aspirin's efficacy and safety for extended VTE prevention. Subgroup analyses included primary and secondary prevention, provoked and unprovoked VTE, and low-dose aspirin. Pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated using a random-effects model, and trial sequential analysis was used to assess the robustness of the evidence. Five trials including 68,554 patients were analyzed. Aspirin (100-160 mg) significantly reduced the risk of VTE, DVT, PE, and VTE-related mortality compared to placebo, particularly in primary prevention and provoked VTE cases. No benefit was observed in secondary prevention, while some benefit emerged for unprovoked VTE, limited to overall VTE risk. Low-dose aspirin (100 mg) did not significantly reduce the incidence of VTE, DVT, or PE. Aspirin increased the risks of overall and major bleeding but did not elevate blood transfusion requirements or major cardiovascular events. These findings suggest that prolonged aspirin therapy may have a role in extended VTE prevention, particularly in patients at risk for provoked VTE. However, careful patient selection remains crucial, and further studies are needed to refine its indications and optimal dosing strategy.