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BACKGROUND: Whether to continue oral anticoagulant therapy beyond 6 months after an "unprovoked" venous thromboembolism is controversial. We sought to determine clinical predictors to identify patients who are at low risk of recurrent venous thromboembolism who could safely discontinue oral anticoagulants. METHODS: In a multicentre prospective cohort study, 646 participants with a first, unprovoked major venous thromboembolism were enrolled over a 4-year period. Of these, 600 participants completed a mean 18-month follow-up in September 2006. We collected data for 69 potential predictors of recurrent venous thromboembolism while patients were taking oral anticoagulation therapy (5-7 months after initiation). During follow-up after discontinuing oral anticoagulation therapy, all episodes of suspected recurrent venous thromboembolism were independently adjudicated. We performed a multivariable analysis of predictor variables (p < 0.10) with high interobserver reliability to derive a clinical decision rule. RESULTS: We identified 91 confirmed episodes of recurrent venous thromboembolism during follow-up after discontinuing oral anticoagulation therapy (annual risk 9.3%, 95% CI 7.7%-11.3%). Men had a 13.7% (95% CI 10.8%-17.0%) annual risk. There was no combination of clinical predictors that satisfied our criteria for identifying a low-risk subgroup of men. Fifty-two percent of women had 0 or 1 of the following characteristics: hyperpigmentation, edema or redness of either leg; D-dimer > or = 250 microg/L while taking warfarin; body mass index > or = 30 kg/m(2); or age > or = 65 years. These women had an annual risk of 1.6% (95% CI 0.3%-4.6%). Women who had 2 or more of these findings had an annual risk of 14.1% (95% CI 10.9%-17.3%). INTERPRETATION: Women with 0 or 1 risk factor may safely discontinue oral anticoagulant therapy after 6 months of therapy following a first unprovoked venous thromboembolism. This criterion does not apply to men.CONTEXTE : La poursuite de l'anticoagulothérapie orale au-delà de six mois suivant une thromboembolie veineuse «spontanée» ne fait pas l'unanimité. Nous avons tenté de d'identifier des facteurs prédictifs cliniques de manière à reconnaître les patients exposés à un risque faible de récurrence de thromboembolie veineuse qui pourraient cesser sans danger leurs anticoagulants oraux. METHODES : Lors d'une étude de cohorte prospective ulticentrique, 646 participants ayant subi une première thromboembolie veineuse majeure spontanée ont été inscrits sur une période de quatre ans. Parmi ces participants, 600 avaient mené à terme 18 mois de suivi en moyenne, en date de septembre 2006. Nous avons recueilli des données sur 69 facteurs prédictifs potentiels de récurrence de thromboembolie veineuse alors que les patients se trouvaient sous anticoagulothérapie orale (5–7 mois après le début). Durant le suivi consécutif à l'arrêt de l'anticoagulothérapie orale, tous les épisodes de récurrence soupçonnée de thromboembolie veineuse ont été évalués de manière indépendante. Nous avons réalisé une a...

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The prevalence of occult cancer was low among patients with a first unprovoked venous thromboembolism. Routine screening with CT of the abdomen and pelvis did not provide a clinically significant benefit. (Funded by the Heart and Stroke Foundation of Canada; SOME ClinicalTrials.gov number, NCT00773448.).