Summary. Background: In patients with unprovoked venous thromboembolism (VTE), the optimal duration of anticoagulation is anchored on estimating the risk of disease recurrence.
Objectives: We aimed to develop a score that could predict the recurrence risk following a first episode of unprovoked VTE, pooling individual patient data from seven prospective studies.
Methods: One thousand eight hundred and eighteen cases with unprovoked VTE treated for at least 3 months with a vitamin K antagonist were available for analysis. Optimism-corrected Cox regression coefficients were used to develop a recurrence score that was subsequently internally validated by bootstrap analysis.
Results: Abnormal D-dimer after stopping anticoagulation, age < 50 years, male sex and VTE not associated with hormonal therapy (in women) were the main predictors of recurrence and were used to derive a prognostic recurrence score (DASH, D-dimer, Age, Sex, Hormonal therapy) showing a satisfactory predictive capability (ROC area = 0.71). The annualized recurrence risk was 3.1% (95% confidence interval [CI], 2.3–3.9) for a score ≤ 1, 6.4% (95% CI, 4.8–7.9) for a score = 2 and 12.3% (95% CI, 9.9–14.7) for a score ≥ 3. By considering at low recurrence risk those patients with a score ≤ 1, life-long anticoagulation might be avoided in about half of patients with unprovoked VTE.
Conclusions: The DASH prediction rule appears to predict recurrence risk in patients with a first unprovoked VTE and may be useful to decide whether anticoagulant therapy should be continued indefinitely or stopped after an initial treatment period of at least 3 months.