Aspirin reduced the risk of recurrent VTE compared to placebo (5.1%/yr vs 7.5%/yr; HR 0.68; 95% CI 0.51-0.90; P=0.008) in patients with a first unprovoked VTE after stopping anticoagulants.
Meta-Analysis (n=1,224)
Yes
Does aspirin reduce recurrent VTE and major vascular events in patients with a first unprovoked VTE who have discontinued anticoagulant treatment?
In patients with a first unprovoked VTE who have stopped anticoagulation, aspirin reduces the risk of recurrent VTE and major vascular events by approximately one-third without significantly increasing major bleeding.
Hazard Ratio: 0.68 (95% CI 0.51–0.9)
Absolute Event Rate: 5.1% vs 7.5%
p-value: p=0.008
BACKGROUND: In patients with a first unprovoked venous thromboembolism (VTE) the risk of recurrent VTE remains high after anticoagulant treatment is discontinued. The Aspirin for the Prevention of Recurrent Venous Thromboembolism (the Warfarin and Aspirin WARFASA) and the Aspirin to Prevent Recurrent Venous Thromboembolism (ASPIRE) trials showed that aspirin reduces this risk, but they were not individually powered to detect treatment effects for particular outcomes or subgroups. METHODS AND RESULTS: An individual patient data analysis of these trials was planned, before their results were known, to assess the effect of aspirin versus placebo on recurrent VTE, major vascular events (recurrent VTE, myocardial infarction, stroke, and cardiovascular disease death) and bleeding, overall and within predefined subgroups. The primary analysis, for VTE, was by intention to treat using time-to-event data. Of 1224 patients, 193 had recurrent VTE over 30.4 months' median follow-up. Aspirin reduced recurrent VTE (7.5%/yr versus 5.1%/yr; hazard ratio HR, 0.68; 95% confidence interval CI, 0.51-0.90; P=0.008), including both deep-vein thrombosis (HR, 0.66; 95% CI, 0.47-0.92; P=0.01) and pulmonary embolism (HR, 0.66; 95% CI, 0.41-1.06; P=0.08). Aspirin reduced major vascular events (8.7%/yr versus 5.7%/yr; HR, 0.66; 95% CI, 0.50-0.86; P=0.002). The major bleeding rate was low (0.4%/yr for placebo and 0.5%/yr for aspirin). After adjustment for treatment adherence, recurrent VTE was reduced by 42% (HR, 0.58; 95% CI, 0.40-0.85; P=0.005). Prespecified subgroup analyses indicate similar relative, but larger absolute, risk reductions in men and older patients. CONCLUSIONS: Aspirin after anticoagulant treatment reduces the overall risk of recurrence by more than a third in a broad cross-section of patients with a first unprovoked VTE, without significantly increasing the risk of bleeding. CLINICAL TRIAL REGISTRATION URL: www.anzctr.org.au. Unique identifier: ACTRN12611000684921.
“The results of this study suggest the simple, inexpensive treatment of low-dose aspirin could prevent thousands of patients from experiencing recurrent clots each year and may make substantial healthcare savings in Australia and worldwide. These results suggest that aspirin prevents about one third of recurrent blood clot events. For every 1000 patients treated for one year, aspirin can be expected to prevent about 20 to 30 episodes of recurrent major thrombotic events at the cost of about three significant bleeding episodes.”
Simes et al. (Mon,) conducted a meta-analysis in First unprovoked venous thromboembolism (VTE) (n=1,224). Aspirin vs. Placebo was evaluated on Recurrent VTE (HR 0.68, 95% CI 0.51-0.90, p=0.008). Aspirin reduced the risk of recurrent VTE compared to placebo (5.1%/yr vs 7.5%/yr; HR 0.68; 95% CI 0.51-0.90; P=0.008) in patients with a first unprovoked VTE after stopping anticoagulants.
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