NOSTRADAMUS: Testing for thrombophilia in patients with a first episode of venous thromboembolism (VTE): a randomized controlled trial to assess effects on clinical outcomes, quality of life, and costs.

A randomized controlled trial of testing and no testing for thrombophilia in patients with a first episode of VTE will be performed. Subsequent additional anticoagulant treatment for a predefined period will be installed in those in whom thrombophilia is detected in the testing group, while others will receive a standard predefined duration of treatment. In addition, the impact on quality of life of thrombophilia testing will be measured. Efficacy and safety outcomes are risk for recurrent VTE and clinically important bleeding (also as a composite outcome). Other outcomes are overall quality of life and costs associated with the outcome measures 18 months after the initial episode of VTE. Outcomes will be compared between thrombophilic patients allocated to the testing group and to the no testing group. A total of 1336 patients will have to be included to detect a benefit of 90% by prolonging anticoagulant treatment in patients with thrombophilia while on treatment, and no reduction in the 6 months after cessation of treatment (overall RRR 55%) [power 80%, CI 95%].

Testing for thrombophilia after a first episode of VTE with subsequent prolongation of anticoagulant treatment in thrombophilic patients is beneficial in terms of clinical outcomes, quality of life, and costs.

Randomization between disclosure and undisclosure of results of thrombophilia screening and subsequent additional anticoagulant treatment for a predefined period will be installed in those in whom thrombophilia is detected in the disclosure group