- Using a previously described algorithm, first-degree relatives were classified as "have had VTE" if they satisfied either of the following two criteria. First, results of diagnostic testing were available that documented previous deep vein thrombosis (including thrombosis confined to the distal deep veins) or pulmonary embolism. Second, they had, in addition to a history of symptoms suggestive of VTE, at least one of the following: i) a history of having been treated with anticoagulant therapy for at least two months without another indication; or ii) a current ultrasound examination that showed that the proximal deep veins were not fully compressible or that there was reflux in a popliteal vein; or iii) current symptoms and signs suggestive of the post-thrombotic syndrome (defined as a score ≥5 on the Villalta scale).