A Phase 4 interventional study of Dalteparin Sodium and Tinzaparin Sodium in Venous Thromboembolism and Varicose Veins, sponsored by Imperial College London. Recruiting at 1 site in United Kingdom. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-06-04.
Sponsored by Imperial College London · Phase 4, Interventional, and Prevention
Endovenous interventions are keyhole operations for varicose veins that are carried out from within the vein itself. Varicose veins are enlarged veins close to the surface of the skin. They are connected to the bigger deeper veins in the leg (known as deep veins). Because of this, operations to close the varicose veins can increase the chance of a blood clot forming in the deep veins. Blood clots in the deep veins happen in around 1 in 50 people after endovenous operations. A clot in the leg can cause swelling, pain, and other long-term problems. If a clot in the leg breaks off and travels to the lungs, it can cause problems with the lung' ability to move oxygen from the air into the blood and may, in rare cases, be life threatening.
Varicose vein procedures may carry a slightly higher risk of blood clot formation, and we are currently unsure if current clot reducing medicines are beneficial in preventing blood clots in people having varicose vein procedures.
This study will investigate if it is worthwhile prescribing medicines to reduce blood clots after varicose vein procedures.
712 studies on the registry are indexed under Venous Thromboembolism; 146 are open to participants now.
This study's planned enrollment of 3,175 is above the median of 240 across 401 interventional studies indexed under Venous Thromboembolism.
Browse Venous Thromboembolism studies →Imperial College London is the lead sponsor of 843 studies on the registry; 180 are open to participants now.
Of its 9 completed or terminated interventional studies of FDA-regulated products, 6 (67%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Known thrombocytopenia ( known to be less than 50 x 109
/l)
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A single prophylactic dose of low molecular weight heparin (LMWH) (e.g., dalteparin sodium, tinzaparin sodium, enoxaparin sodium) will be prescribed as per standard practice and administered in accordance with the relevant Summary of Product Characteristics (SmPC), manufacturer's recommendations and instructions for use.
Drug: Dalteparin Sodium · Drug: Tinzaparin Sodium · Drug: Enoxaparin Sodium
An extended duration of LMWH (e.g., dalteparin sodium, tinzaparin sodium, enoxaparin sodium) or an extended duration of a direct oral anticoagulant (DOAC) (e.g., rivaroxaban, apixaban, dabigatran etexilate) will be prescribed as per current local practice and administered in accordance with the relevant SmPC, manufacturer's recommendations and instructions for use. The duration of this must be at least 7 days, but can be in line with local practice i.e., 7, 10 or 14 days.
Drug: Dalteparin Sodium · Drug: Tinzaparin Sodium · Drug: Enoxaparin Sodium · Drug: Rivaroxaban · Drug: Apixaban · Drug: Dabigatran Etexilate
Low molecular weight heparin
Low molecular weight heparin
Low molecular weight heparin
Direct oral anticoagulant
Direct oral anticoagulant
Direct oral anticoagulant
Imaging confirmed lower limb deep vein thrombosis (DVT) with or without symptoms, or pulmonary embolism (PE) with symptoms within 90 days of varicose vein treatment.
The rate of lower limb DVT with or without symptoms, or PE with symptoms within 90 days of varicose vein treatment.
Time frame: 90 days
Lower limb DVT without symptoms
Duplex ultrasound scan
Time frame: 21 - 28 days
Lower limb DVT with symptoms
Self-reported VTE outcome questionnaire
Time frame: 90 days
PE with symptoms
VTE outcome questionnaire (self-reported) to determine the rate of PE
Time frame: 90 days
Comparisons of quality of life at 7- and 90-days post-procedure
Using EQ-5D
Time frame: 90-days
Cost-effectiveness of providing pharmacological thromboprophylaxis
Incremental Cost-Effectiveness Ratio (ICER)
Time frame: 90 days
Exploratory analyses to assess how well a VTE risk assessment tool predicts VTE outcome
Venous thromboembolism risk as determined by the Department of Health Risk Assessment tool
Time frame: 90 days
Exploratory analyses to assess how well a VTE risk assessment tool predicts VTE outcome
Venous thromboembolism risk as determined by the Caprini risk assessment model
Time frame: 90 days
Mortality rates in each group
Rate of mortality
Time frame: 90 days
Plan to share: No
No publications or documents are linked to this record.
Started Jan 2024 (actual). Primary completion is estimated for Jun 2027, 41 months after the start.
Of 34 phase 4 interventional studies under Venous Thromboembolism, half reached primary completion within 24 months of starting (the median), counting those still running; a quarter within 16 and three quarters within 88. This study's planned 41 months is above that.
How these figures are worked out, and which studies are left out of them.
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Studies of the drugs tested here: Dalteparin · Tinzaparin · Enoxaparin sodium · Rivaroxaban · Apixaban · Dabigatran