Assessing Recurrence Risk Following Acute Venous Thromboembolism

Use of Algorithms

Daniela Poli; Gualtiero Palareti


Curr Opin Pulm Med. 2013;19(5):407-412. 

In This Article


Despite research about the duration of anticoagulant treatment for unprovoked VTE and the identification of risk factors for recurrence, the optimal duration of treatment after an initial 3–6 months of therapy is still uncertain. Patients carrying an elevated risk of recurrence should be maintained on anticoagulant treatment, whereas patients with a low risk should not. An expert consensus has recently been published,[48] concluding that an annual risk of recurrent VTE below 5% can be considered acceptable, taking into account an annual bleeding risk of anticoagulation of 1–3% overall and of 4–5% in the elderly.[49] Therefore, any algorithm should accept a yearly recurrent risk of 5% to discriminate patients who need to be maintained on long-term treatment and those who do not. All proposed algorithms are in keeping with this indication. However, though all the different models identify male sex and elevated D-dimer as important risk factors for recurrence, several crucial differences among the models are present. In the HERDOO2 model, D-dimer is measured during anticoagulation and age greater than 65 years is indicated as risk factor for recurrence; on the contrary, the DASH score attributes a higher risk to young age (<50 years). Further studies are needed to clarify these discrepancies. The three algorithms proposed could help clinicians in daily practice, and the DASH model seems the easiest to be used. Further studies are needed to better validate the different models.

An intermediate strategy has recently been proposed aiming to reduce VTE recurrence in patients with unprovoked VTE. Two recent randomized trials compared the effect of low-dose aspirin administration vs. placebo after a first course of standard anticoagulant therapy and found a 25–30% reduction in the risk for recurrent VTE in patients who received low-dose aspirin.[50,51] In our opinion, however, further prospective studies are needed to explore the validity of this approach, especially if we bear in mind that the bleeding risk of low-dose aspirin is not negligible and not that different from the risk of bleeding associated with standard anticoagulation, especially in elderly patients.[52]