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Compression stockings to prevent post-thrombotic syndrome: The SOX trial
ISRCTN ISRCTN71334751
DOI 10.1186/ISRCTN71334751
ClinicalTrials.gov identifier NCT00143598
EudraCT number
Public title Compression stockings to prevent post-thrombotic syndrome: The SOX trial
Scientific title Compression stockings to prevent post-thrombotic syndrome: a multicentre, two arm, placebo-controlled randomised parallel device trial
Acronym SOX
Serial number at source MCT-63142
Study hypothesis To determine whether Elastic Compression Stockings (ECS) used for two years are effective in preventing the Post-Thrombotic Syndrome (PTS) in patients with symptomatic proximal Deep Venous Thrombosis (DVT).

Please note that in 2005, the intervention using Celecoxib was removed from this trial due to reports of negative effects in a large colorectal cancer prevention clinical trial. Thus, the SOX Trial protocol was amended to take this into account. The most recent changes to the protocol were made to this trial record on the 10th June 2009.

Previous hypothesis:
To determine whether Elastic Compression Stockings (ECS) used for two years, and celecoxib, a COX-II inhibitor, used for 30 days are effective in preventing the Post-Thrombotic Syndrome (PTS) in patients with symptomatic proximal Deep Venous Thrombosis (DVT).

As of 17/02/2010 this record has been updated to include an extended anticipated end date; the intial anticipated end date of this record was 30/12/2011. Please note that enrolment to this trial is now completed.

Sub -study registered with ClinicalTrials.gov: NCT01615705 - Biomarker Sub Study of the Compression Stockings to Prevent the Post-Thrombotic Syndrome (SOX) Trial (Bio-SOX)

Sub -study registered with ClinicalTrials.gov: NCT01615692 - The 36-month Extension to Follow up Sub Study
Lay summary Not provided at time of registration
Ethics approval 1. Canada: The Research Ethics Committee of Sir Mortimer B Davis Jewish General Hospital approved on the 30th July 2003. This ethics approval was amended on the 27th January 2005 to take into account the removal of the celecoxib intervention and consequent protocol changes.
2. USA: The University of Oklahoma Health Sciences Center Institutional Review Board (USA) approved on the 31st July 2007 (ref: 13513). All other centres subsequent to this in the USA will require full ethics approval before recruiting participants.
Study design Multicentre, two arm, placebo randomised parallel device trial with study participant, study investigator, and outcome assessor blinded.
Countries of recruitment Canada, United States of America
Disease/condition/study domain Deep vein thrombosis
Participants - inclusion criteria Current inclusion criteria (protocol updated in August 2008):
Consecutive patients aged greater than or equal to 18 years old, either sex, with a first, symptomatic, objectively confirmed proximal DVT diagnosed within the last 14 days (with or without concurrent distal DVT or Pulmonary Embolism [PE]) who have no contraindications to standard treatment with heparin and/or warfarin, and who provide informed consent to participate.

Previous inclusion criteria (January 2005):
Consecutive patients aged greater than or equal to 18 years old, either sex, with a first, symptomatic, objectively confirmed proximal DVT diagnosed within the last 10 days (with or without concurrent distal DVT or Pulmonary Embolism [PE]) who have no contraindications to standard treatment with heparin and/or warfarin, and who provide informed consent to participate.

Initial inclusion criteria (January 2004):
Consecutive patients with a first, symptomatic, objectively confirmed proximal DVT diagnosed within the last 72 hours (with or without concurrent distal DVT or Pulmonary Embolism [PE]) who have no contraindications to standard treatment with heparin and/or warfarin, and who provide informed consent to participate.
Participants - exclusion criteria Current exclusion criteria (protocol updated in January 2005):
1. Contraindication to compression stockings
2. Limited lifespan (estimated less than six months)
3. Geographic inaccessibility preventing return for follow-up visits
4. Inability to apply stockings daily and unavailability of a caregiver to apply stockings daily
5. Treatment of acute DVT with thrombolytic agents

Previous exclusion criteria:
1. Contraindication to compression stockings
2. Contraindication to celecoxib
3. History of warfarin, aspirin or Non-Steroidal Anti-Inflammatory Drug (NSAID)-associated major haemorrhagic event
4. Regular, daily use of NSAIDs
5. Inability/unwillingness to stop anti-platelet drugs for 30 days
6. Limited lifespan (estimated less than six months)
7. Geographic inaccessibility preventing return for follow-up visits
8. Inability to apply stockings daily and unavailability of a caregiver to apply stockings daily
9. Treatment of acute DVT with thrombolytic agents
Anticipated start date 01/04/2003
Anticipated end date 31/01/2012
Status of trial Completed
Patient information material
Target number of participants 800
Interventions Current interventions (protocol updated in January 2005):
1. Experimental interventions: knee-length, 30 - 40 mmHg (Class II), graduated ECS worn on the DVT-affected leg daily, applied upon waking and removed upon retiring, beginning within a week (as soon as possible) after DVT diagnosis, and continued for two years
2. Control interventions: knee-length, inactive (i.e. no compression) stocking, identical in appearance to active ECS, worn on the DVT-affected leg daily, applied upon waking and removed upon retiring, beginning within a week (as soon as possible) after DVT diagnosis, and continued for two years

Due to the removal of the Celecoxib intervention, the recruitment resumed in February 2005, and the anticipated end date of this trial has now been extended by one year to 30th December 2011 (amended 10/06/2009). The previous anticipated end date of this trial was 30/03/2008 (amended 13/05/2008).

Contact for public queries as of 13/05/2008:
Susan Kahn MD, MSc
SOX Trial Principal Investigator
SMBD Jewish General Hospital
Phone: +1 514 340 8222 ext. 4667
Fax: +1 514 340 7564
E-mail: susan.kahn@mcgill.ca

Previous interventions:
1. Experimental interventions:
1.1. Knee-length, 30 - 40 mmHg (Class II), graduated ECS worn on the DVT-affected leg daily, applied upon waking and removed upon retiring, beginning within a week (as soon as possible) after DVT diagnosis, and continued for two years
1.2. Celecoxib, 200 mg orally (po) twice a day (BID), begun on the day of DVT diagnosis and continued for 30 days
2. Control interventions:
2.1. Knee-length, inactive (i.e. no compression) stocking, identical in appearance to active ECS, worn on the DVT-affected leg daily, applied upon waking and removed upon retiring, beginning within a week (as soon as possible) after DVT diagnosis, and continued for two years
2.2. Placebo, identical in appearance to celecoxib, one tablet po BID, begun on the day of DVT diagnosis and continued for 30 days
Primary outcome measure(s) Incidence of post-thrombotic syndrome (PTS) at two years.
Secondary outcome measure(s) Current secondary outcome measures (protocol updated in January 2005)
1. Severity of PTS at two years follow up, including incidence of venous ulcer
2. Incidence of objectively confirmed recurrent VTE, and death from VTE, over two years
3. C-reactive protein at 30 days compared to baseline value
4. Quality of life over the two-year follow up
5. Cost-effectiveness

Previous secondary outcome measures:
1. Severity of PTS at two years follow up, including incidence of venous ulcer
2. Incidence of objectively confirmed recurrent VTE, and death from VTE, over two years
3. Incidence of major bleeding or arterial thrombotic events during the first 60 days
4. C-reactive protein at 30 days compared to baseline value
5. Quality of life over the two-year follow up
6. Cost-effectiveness
Sources of funding 1. Canadian Institutes of Health Research (CIHR) (Canada) - http://www.cihr-irsc.gc.ca (ref: MCT-63142)
2. SIGVARIS Corp. (Canada)
Trial website
Publications 2007 protocol in: http://www.ncbi.nlm.nih.gov/pubmed/17711595
2014 results in: http://www.ncbi.nlm.nih.gov/pubmed/24315521
Contact name Dr  Susan Rebecca  Kahn
  Address Center for Clinical Epidemiology and Community Studies
SMBD Jewish General Hospital
3755 Cote Ste. Catherine Rm A-127
  City/town Montreal, Quebec
  Zip/Postcode H3T 1E2
  Country Canada
  Tel +1 514 3408222 (4667)
  Fax +1 514 3407564
  Email susan.kahn@mcgill.ca
Sponsor Sir Mortimer B. Davis Jewish General Hospital-Mtl (Canada)
  Address 3755 Côte Ste-Catherine Road
  City/town Montreal, Quebec
  Zip/Postcode H3T 1E2
  Country Canada
  Tel +1 514 340 8222
  Fax +1 514 340 7510
  Email wainberg@ldi.jgh.mcgill.ca
Date applied 01/09/2005
Last edited 25/03/2014
Date ISRCTN assigned 01/09/2005
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