Trial Outcomes & Findings for The SOX Trial: Compression Stockings to Prevent the Post-Thrombotic Syndrome (NCT NCT00143598)

NCT ID: NCT00143598

Last Updated: 2014-08-18

Results Overview

• Recruitment status: COMPLETED
• Study phase: PHASE3
• Target enrollment: 806 participants
• Primary outcome timeframe: During 2-year follow up
• Results posted on: 2014-08-18

Participant Flow

Between June, 2004, and February, 2010, we enrolled patients in 24 centres in Canada and the USA.

Patients were excluded if they had a contraindication to the use of compression stockings, an expected life span of <6 months, geographical inaccessibility, were unable to apply stockings, or received thrombolytic therapy for the initial treatment of acute deep vein thrombosis (DVT).

Participant milestones

Measure	Active ECS Active Elastic Compression Stockings. 30-40 mm Hg	Placebo ECS Placebo stockings with identical appearance but less than 5 mm Hg compression at the ankle.
Overall Study STARTED	410	396
Overall Study COMPLETED	318	302
Overall Study NOT COMPLETED	92	94

Reasons for withdrawal

Measure	Active ECS Active Elastic Compression Stockings. 30-40 mm Hg	Placebo ECS Placebo stockings with identical appearance but less than 5 mm Hg compression at the ankle.
Overall Study Lost to Follow-up	23	21
Overall Study Withdrawal by Subject	33	37
Overall Study Death	36	36

Baseline Characteristics

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

Baseline characteristics by cohort

Measure	Active ECS n=409 Participants Active Elastic Compression Stockings. 30-40 mm Hg	Placebo ECS n=394 Participants Placebo stockings with identical appearance but less than 5 mm Hg compression at the ankle.	Total n=803 Participants Total of all reporting groups
Age, Continuous	55.4 years STANDARD_DEVIATION 15.3 • n=5 Participants	54.8 years STANDARD_DEVIATION 15.8 • n=7 Participants	55.1 years STANDARD_DEVIATION 15.5 • n=5 Participants
Age, Customized <40 years	67 participants n=5 Participants	67 participants n=7 Participants	134 participants n=5 Participants
Age, Customized 40-65 years	222 participants n=5 Participants	217 participants n=7 Participants	439 participants n=5 Participants
Age, Customized >65 years	120 participants n=5 Participants	110 participants n=7 Participants	230 participants n=5 Participants
Sex: Female, Male Female	154 Participants n=5 Participants	166 Participants n=7 Participants	320 Participants n=5 Participants
Sex: Female, Male Male	255 Participants n=5 Participants	228 Participants n=7 Participants	483 Participants n=5 Participants
Race/Ethnicity, Customized White ethnic origin	371 participants n=5 Participants	354 participants n=7 Participants	725 participants n=5 Participants
Outpatients	355 participants n=5 Participants	344 participants n=7 Participants	699 participants n=5 Participants
Body-mass index, kg/m2	29.0 kg/m^2 STANDARD_DEVIATION 6.1 • n=5 Participants	28.9 kg/m^2 STANDARD_DEVIATION 6.1 • n=7 Participants	28.95 kg/m^2 STANDARD_DEVIATION 6.1 • n=5 Participants
Time from DVT diagnosis to randomization	4.8 days STANDARD_DEVIATION 4.1 • n=5 Participants	4.6 days STANDARD_DEVIATION 3.8 • n=7 Participants	4.7 days STANDARD_DEVIATION 3.9 • n=5 Participants
Side of DVT Left	180 participants n=5 Participants	173 participants n=7 Participants	353 participants n=5 Participants
Side of DVT Right	222 participants n=5 Participants	216 participants n=7 Participants	438 participants n=5 Participants
Side of DVT Bilateral	7 participants n=5 Participants	5 participants n=7 Participants	12 participants n=5 Participants
Most proximal extent of DVT Iliac vein	44 participants n=5 Participants	49 participants n=7 Participants	93 participants n=5 Participants
Most proximal extent of DVT Common femoral vein	109 participants n=5 Participants	107 participants n=7 Participants	216 participants n=5 Participants
Most proximal extent of DVT Femoral Vein	128 participants n=5 Participants	123 participants n=7 Participants	251 participants n=5 Participants
Most proximal extent of DVT Popliteal vein	128 participants n=5 Participants	115 participants n=7 Participants	243 participants n=5 Participants
Villalta score at baseline	8.2 Score on a scale STANDARD_DEVIATION 4.4 • n=5 Participants	8.7 Score on a scale STANDARD_DEVIATION 4.8 • n=7 Participants	8.4 Score on a scale STANDARD_DEVIATION 4.6 • n=5 Participants
Concurrent pulmonary embolism	57 participants n=5 Participants	57 participants n=7 Participants	114 participants n=5 Participants
Venous thrombosis risk factors Surgery, past 3 months	77 participants n=5 Participants	64 participants n=7 Participants	141 participants n=5 Participants
Venous thrombosis risk factors Trauma, past 3 months	42 participants n=5 Participants	51 participants n=7 Participants	93 participants n=5 Participants
Venous thrombosis risk factors Immobilised in past month	67 participants n=5 Participants	61 participants n=7 Participants	128 participants n=5 Participants
Venous thrombosis risk factors Active cancer	52 participants n=5 Participants	46 participants n=7 Participants	98 participants n=5 Participants
Venous thrombosis risk factors Pregnant, post partum, OCT, or HRT	37 participants n=5 Participants	55 participants n=7 Participants	92 participants n=5 Participants
Venous thrombosis risk factors Family history of venous thromboembolism	85 participants n=5 Participants	82 participants n=7 Participants	167 participants n=5 Participants
Type of DVT Treatment Low molecular weight heparin	388 participants n=5 Participants	384 participants n=7 Participants	772 participants n=5 Participants
Type of DVT Treatment Unfractionated heparin	31 participants n=5 Participants	21 participants n=7 Participants	52 participants n=5 Participants
Type of DVT Treatment Warfarin	330 participants n=5 Participants	317 participants n=7 Participants	647 participants n=5 Participants
Type of DVT Treatment Investigational anitcoagulant	15 participants n=5 Participants	11 participants n=7 Participants	26 participants n=5 Participants
Duration of DVT Treatment Duration of heparin	8 days n=5 Participants	8 days n=7 Participants	8 days n=5 Participants
Duration of DVT Treatment Duration of Oral Anti-Coagulation (OAC)	186 days n=5 Participants	182 days n=7 Participants	185 days n=5 Participants

PRIMARY outcome

Timeframe: During 2-year follow up

Population: Intention to treat.

Outcome measures

Measure	Active ECS n=409 Participants Active Elastic Compression Stockings (ECS) 30-40 mm Hg compression at the ankle.	Placebo ECS n=394 Participants Placebo stockings with identical appearance to Active ECS and with \< 5 mm Hg compression at the ankle.
Incidence of Post-thrombotic Syndrome (PTS)	44 participants	37 participants

SECONDARY outcome

Timeframe: 6-24 months.

Population: Highest Villalta score at or after 6 month visit (missing for 48 patients in each group).

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.

Outcome measures

Measure	Active ECS n=361 Participants Active Elastic Compression Stockings (ECS) 30-40 mm Hg compression at the ankle.	Placebo ECS n=346 Participants Placebo stockings with identical appearance to Active ECS and with \< 5 mm Hg compression at the ankle.
Severity of PTS, Including Incidence of Venous Ulcer None (score <5)	185 participants	178 participants
Severity of PTS, Including Incidence of Venous Ulcer Mild (5-9)	119 participants	111 participants
Severity of PTS, Including Incidence of Venous Ulcer Moderate (10-14)	30 participants	37 participants
Severity of PTS, Including Incidence of Venous Ulcer Severe (>14 or ulcer)	27 participants	20 participants

SECONDARY outcome

Timeframe: During 2-year follow up

Outcome measures

Measure	Active ECS n=409 Participants Active Elastic Compression Stockings (ECS) 30-40 mm Hg compression at the ankle.	Placebo ECS n=394 Participants Placebo stockings with identical appearance to Active ECS and with \< 5 mm Hg compression at the ankle.
Incidence of Objectively Confirmed Recurrent Venous Thromboembolism (VTE), Death From VTE and Major Bleeding Recurrent venous thromboembolism	33 participants	38 participants
Incidence of Objectively Confirmed Recurrent Venous Thromboembolism (VTE), Death From VTE and Major Bleeding Death from VTE	0 participants	0 participants
Incidence of Objectively Confirmed Recurrent Venous Thromboembolism (VTE), Death From VTE and Major Bleeding Major bleeding	11 participants	14 participants

SECONDARY outcome

Timeframe: 24 months

Population: Patients who completed the SF-36 and VEINES-QOL at 24 months follow-up.

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.

Outcome measures

Measure	Active ECS n=268 Participants Active Elastic Compression Stockings (ECS) 30-40 mm Hg compression at the ankle.	Placebo ECS n=261 Participants Placebo stockings with identical appearance to Active ECS and with \< 5 mm Hg compression at the ankle.
Quality of Life SF-36 PCS	46.7 Scores on a scale Standard Deviation 10.7	47.5 Scores on a scale Standard Deviation 10.2
Quality of Life SF-36 MCS	52.7 Scores on a scale Standard Deviation 9.3	52.5 Scores on a scale Standard Deviation 8.8
Quality of Life VEINES-QOL	56.6 Scores on a scale Standard Deviation 5.3	57.4 Scores on a scale Standard Deviation 5.3

Adverse Events

Active ECS

Serious events: 0 serious events

Other events: 8 other events

Deaths: 0 deaths

Placebo ECS

Serious events: 0 serious events

Other events: 7 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Measure	Active ECS n=409 participants at risk Active Elastic Compression Stockings (ECS) 30-40 mm Hg compression at the ankle.	Placebo ECS n=394 participants at risk Placebo stockings with identical appearance to Active ECS and with \< 5 mm Hg compression at the ankle.
Skin and subcutaneous tissue disorders Rash/Itching	2.0% 8/409 • Number of events 8 • 24 months	1.8% 7/394 • Number of events 7 • 24 months

Additional Information

Dr. Susan R Kahn

Centre for Clinical Epidemiology, Jewish General Hospital

Phone: 514-340-8222

Email: susan.kahn@mcgill.ca

Results disclosure agreements

• Principal investigator is a sponsor employee
• Publication restrictions are in place