Several individual characteristics such as post-anticoagulation D-dimer and residual venous obstruction have been shown to be associated with an increased risk of recurrent events. We have shown in a multicentre randomized study PROLONG (N Engl J Med 2006; 355: 1780-1789) showed that D-dimer could play a role in establishing the duration of anticoagulation after a first episode of idiopathic VTE. Patients were treated with VKA for a minimum of 3 months and D-d was tested at one month after anticoagulation withdrawal . If D-dimer was normal patients did not resume treatment, whereas those with elevated D-dimer were randomized to either stop or resume anticoagulation. Patients with an abnormal D-dimer had a statistically significant higher risk for recurrence when compared with those with normal D-d. Continued anticoagulation in patients with elevated D-d significantly reduced the risk of recurrent VTE over a follow-up of 18 months.