The optimal duration of anticoagulation for venous thromboembolism (VTE) following a transient provoking factor in patients with co-existing enduring risk factors remains a clinical question. The HI-PRO trial investigated whether extended, low-dose apixaban could safely reduce the risk of recurrence in this specific patient population.¹

The HI-PRO trial was a single-centre, double-blind, randomised, placebo-controlled study involving 600 adults with VTE that occurred after a transient provoking factor, such as surgery, trauma, or immobility. To be included, patients were required to have at least one enduring risk factor and have completed a minimum of three months of standard anticoagulation therapy.

Participants were randomly assigned to receive either oral apixaban at a dose of 2.5 mg twice daily or a matching placebo for a duration of 12 months. The primary efficacy outcome was the first occurrence of symptomatic recurrent VTE. The primary safety outcome was the first episode of major bleeding, as defined by the International Society on Thrombosis and Haemostasis criteria.¹

The trial enrolled 600 patients (mean age, 59.5 years; 57.0% female). The primary efficacy outcome of symptomatic recurrent VTE occurred in 4 of 300 patients (1.3%) in the apixaban group, compared with 30 of 300 patients (10.0%) in the placebo group (hazard ratio [HR], 0.13; 95% confidence interval [CI], 0.04 to 0.36; P<0.001).

Regarding safety, one patient in the apixaban group experienced a major bleeding event, while no major bleeds occurred in the placebo group. Clinically relevant nonmajor bleeding was observed in 14 patients (4.8%) in the apixaban group and 5 patients (1.7%) in the placebo group (HR, 2.68; 95% CI, 0.96 to 7.43; P=0.06).

There was one death in the apixaban group and three in the placebo group; none were attributed to cardiovascular or haemorrhagic causes.¹

Among patients with a provoked VTE who also have enduring risk factors, extended therapy with low-dose apixaban for 12 months resulted in a significantly lower risk of symptomatic recurrent VTE than placebo. This efficacy was achieved with a low associated risk of major bleeding.

This study was funded by Bristol-Myers Squibb–Pfizer Alliance.

References

1. Piazza G, Bikdeli B, Pandey AK, et al. Apixaban for Extended Treatment of Provoked Venous Thromboembolism. N Engl J Med. Published online August 30, 2025. https://doi.org/10.1056/NEJMoa2509426.

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