Individualised versus standard duration of elastic compression therapy for prevention of post-thrombotic syndrome (IDEAL DVT): a multicentre, randomised, single-blind, allocation-concealed, non-inferiority trial

Background Therapy with elastic compression stockings has been the cornerstone for prevention of post-thrombotic syndrome for decades in patients after acute deep venous thrombosis. It is uncertain who benefits most from therapy, and what the optimum duration of therapy should be. We therefore aimed to assess the safety and efficacy of individualised duration of compression therapy versus the standard duration of 24 months following an initial treatment period of 6 months. Methods We did a multicentre, randomised, single-blind, allocation-concealed, non-inferiority trial at 12 hospitals in the Netherlands and two in Italy. We randomly assigned patients (1:1) with acute proximal deep vein thrombosis of the leg and without pre-existent venous insufficiency (Clinical Etiological Anatomical and Pathophysiological score <C3) to receive either individualised duration of elastic compression therapy or standard duration of therapy for 24 months following an initial treatment period of 6 months. Randomisation was done with a web-based automatic randomisation programme (TENALEA) and a random block size (2-12), and was stratified by centre, age, and body-mass index. In the initial phase, compression was applied within 24 h of diagnosis according to three prespecified protocols. All patients received elastic compression stockings (30-40 mm Hg) for 6 months, and were instructed to wear them every day during ambulant hours. Thereafter treatment was tailored on the basis of clinical signs and symptoms scored according to the Villalta post-thrombotic syndrome scale; patients assigned to individualised therapy with two consecutive Villalta scores of 4 or less were instructed to stop using the stockings. Patients were followed up for 2 years and assessed at five clinic visits at study inclusion, and 3, 6, 12, and 24 months after diagnosis (stocking allocation was not revealed to the assessors). The primary outcome was the proportion of patients with post-thrombotic syndrome at 24