The SOX Trial: Compression Stockings to Prevent the Post-Thrombotic Syndrome

Study Overview
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Brief Summary
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The purpose of this study is to determine whether elastic compression stockings used for 2 years are effective in preventing the post-thrombotic syndrome in patients with symptomatic proximal deep venous thrombosis.

Detailed Description
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The post-thrombotic syndrome (PTS) is a frequent, burdensome and costly condition that occurs in about one third of patients after an episode of deep vein thrombosis (DVT). Affected patients have chronic leg pain and swelling, and sometimes develop skin ulcers. At present, there is little to offer for the treatment of this condition. Prevention of PTS is the key to reducing its burden on patients and society. Elastic compression stockings (ECS) could be helpful in preventing PTS, however data on their effectiveness are scarce and conflicting. Comparison(s): Knee-length, 30-40 mm Hg (Class II), graduated ECS worn on the DVT-affected leg daily for 2 years compared to knee-length, inactive (i.e. no compression) stocking, identical in appearance to active ECS, worn on the DVT-affected leg daily for 2 years.

Official Title
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The SOX Trial: Compression Stockings to Prevent the Post-Thrombotic Syndrome After Symptomatic Proximal Deep Venous Thrombosis

Conditions
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Deep Venous Thrombosis

Intervention / Treatment
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* Device: Knee-length, graduated elastic compression stocking
* Device: Knee-length, placebo stocking


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Consecutive patients with a first, symptomatic, objectively confirmed proximal DVT diagnosed within the last 14 days (with or without concurrent distal DVT or pulmonary embolism) Who have no contraindications to standard treatment with heparin and/or warfarin, and Who provide informed consent to participate Exclusion Criteria: Contraindication to compression stockings Limited lifespan (estimated < 6 months) Geographic inaccessibility preventing return for follow-up visits Inability to apply stockings daily and unavailability of a caregiver to apply stockings daily Treatment of acute DVT with thrombolytic agents

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Active ECS<br>Active Elastic Compression Stockings (ECS) 30-40 mm Hg compression at the ankle. | Device: Knee-length, graduated elastic compression stocking<br>* Worn daily for 2 years, 30-40 mm Hg<br>|
| Placebo Comparator: Placebo ECS<br>Placebo stockings with identical appearance to Active ECS and with < 5 mm Hg compression at the ankle. | Device: Knee-length, placebo stocking<br>* Worn daily for two years<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of Post-thrombotic Syndrome (PTS) |  | During 2-year follow up | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Severity of PTS, Including Incidence of Venous Ulcer | Highest Villalta at or after 6 month visit The Villalta Scale for assessment of the post-thrombotic syndrome The Villalta scale has a range of 0-33. A Villalta scale score >4 indicates post-thrombotic syndrome (severity of post-thrombotic syndrome is categorized as 5-9 points, mild; 10-14 points, moderate; >14 points or presence of an ulcer, severe). Higher values signify worse outcome. Points on each item in the scale are simply summed to a total score. | 6-24 months. | 
| Incidence of Objectively Confirmed Recurrent Venous Thromboembolism (VTE), Death From VTE and Major Bleeding |  | During 2-year follow up | 
| Quality of Life | The SF-36 is a well-validated generic quality-of-life (QOL) instrument. It includes questions on both physical and mental health. Higher scores indicate a better QOL. The VEINES-QOL is a venous-disease specific QOL measure that consists of 25 items that quantify venous disease effect on QOL, and an embedded symptom sub-questionnaire (VEINES-Sym) with 10 items that measures venous symptoms. Higher scores are associated with better QOL. The VEINES-QOL/Sym and SF-36 use the standard method for scoring questionnaires with items with different response scales that is now routinely used. Raw scores are first transformed to z score equivalents (mean, 0; standard deviation, 1), which then are transformed to T scores (mean, 50; standard deviation, 10) to give an easily understood range of scores. A person-specific estimate is imputed for any missing item in cases where the patient answered at least 50% of the items in the scale. | 24 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Postphlebitic Syndrome, Post-Thrombotic Syndrome, Elastic Stockings, Stockings, Compression, Randomized Controlled Trials, Quality of Life