(Vienna, 18 August 2026) New study findings from a research team at the Department of Medicine I at MedUni Vienna challenge the current understanding of so-called "provoked" venous thromboembolism. A prospective study, recently published in the journal "Blood" shows that, in certain patients, the risk of recurrent thrombosis or pulmonary embolism after discontinuation of anticoagulant therapy may be substantially higher than previously assumed.
Venous thromboembolism (VTE), which includes deep vein thrombosis and pulmonary embolism, is frequently triggered by transient risk factors such as surgery, acute illness with immobilization, or the use of hormonal contraceptives. Once such a risk factor has resolved, the risk of recurrence has traditionally been considered relatively low. Anticoagulation in these patients is therefore generally limited in duration. However, transient risk factors vary considerably in strength – and, as the new data suggest, potentially also in the long-term risk of recurrent VTE.
A research team from the Division of Hematology and Hemostaseology at the Department of Medicine I at MedUni Vienna investigated this question as part of the Austrian Study on Recurrent Venous Thromboembolism. Sabine Eichinger acted as first and corresponding author, Paul A. Kyrle served as principal investigator; Alexandra Kaider and Georg Heinze from the Institute of Clinical Biometrics at MedUni Vienna also contributed to the research.
The prospective study included patients with VTE triggered by a transient risk factor. According to criteria established by the International Society on Thrombosis and Haemostasis (ISTH), triggers were classified as major or minor transient risk factors. After discontinuation of anticoagulation, patients were followed for up to two years for recurrent thrombosis and pulmonary embolism.
The findings were unexpected: Overall, 20 of the 242 patients experienced recurrent VTE. The risk was particularly high among patients whose initial VTE was associated with a major transient risk factor. In this group, the cumulative risk of recurrence was 11.5% after one year and 19.7% after two years. Most recurrent events occurred in patients whose initial VTE had developed in the setting of major surgery.
The risk was substantially lower following minor transient risk factors, with cumulative recurrence rates of 1.9% after one year and 5.0% after two years. The prognosis was particularly favorable among women whose VTE had occurred exclusively in association with combined hormonal contraceptive use. Among 81 women in this group, not a single recurrent VTE was observed during follow-up.
The study therefore provides a more differentiated picture of VTE events that have traditionally been grouped together as “provoked” VTE. The findings point to distinctly different risk profiles: a high risk of recurrence following major transient triggers, particularly major surgery; an intermediate risk associated with other transient risk factors; and a very low risk among women whose VTE was exclusively associated with hormonal contraception.
These findings may have direct implications for clinical decision-making. "They suggest that patients with provoked VTE should no longer be regarded as a uniform low-risk group. Instead, decisions regarding the duration of anticoagulation should take into account the type and strength of the triggering risk factor and be based on a more individualized assessment of recurrence risk", says Sabine Eichinger.
Publication: Blood
Risk of recurrence in patients with provoked venous thromboembolism: a prospective cohort study.
Eichinger S, Eischer L, Kaider A, Heinze G, Quehenberger P, Kyrle PA.
doi: 10.1182/blood.2026034774. Epub ahead of print. PMID: 42574295.).