Reducing the rate of blood clots in patients undergoing varicose vein treatment

Plain English Summary

Background and study aims
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. Endovenous interventions are keyhole operations for varicose veins that are carried out from within the vein itself. 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 problems. If a clot in the leg travels to the lungs, it may be life-threatening. Medicines to reduce the blood's tendency to form clots are often prescribed to patients at high risk of blood clots. However, it is unclear if these clot-reducing medicines are beneficial in preventing blood clots in people having these varicose vein procedures. Elastic stockings that squeeze the leg and improve the blood flow through the veins are applied after the varicose vein procedure which helps to reduce the risk of blood clots. This study will investigate if it is worthwhile to prescribe medicines to reduce blood clots after varicose vein procedures. People enrolled in the study will undergo an assessment to make sure that they don’t have the most important risk factors for clots.

Who can participate?
Patients aged over 18 years scheduled to undergo endovenous treatment of varicose veins under local anaesthetic

What does the study involve?
Participants will receive stockings along with, at random, one of the following three treatments:
1. No clot-reducing medicine, or
2. A single dose of clot-reducing medicine, or
3. An extended course (7-14 days) of clot-reducing medicine
Everyone in the study will get an ultrasound scan 21-28 days after their operation to check if they have not developed a blood clot. This scan is not routinely performed in the NHS and is an additional scan to ensure that all blood clots are detected early. Participants will also receive a phone call 7- and 90-days after their procedure to see if they have developed a blood clot or had any problems with the treatment.

What are the possible benefits and risks of participating?
Patients who would not normally be given blood thinning medication as standard treatment may be assigned to the blood thinning medication group and thus may have a lower risk of developing a blood clot. Similarly, patients who would have normally received blood thinning medication and may have experienced an adverse reaction to this treatment may be assigned to the group receiving only elastic stockings, thus reducing the likelihood of potentially experiencing an adverse reaction to the medication. In addition to this, participants in all arms of the trial will be monitored closely for any complications of blood thinners and stockings, so that any complications can be detected and acted upon. Participants will have an extra non-invasive leg scan about 3 weeks after their procedure to detect any asymptomatic blood clots in the legs. Patients not entered into the study would not normally be offered this scan unless they showed symptoms.
The trial will be continually monitored for safety and stopped at any time on the recommendation of the data monitoring committee if there is marked clinical harm resulting in a lack of equipoise and it being deemed unethical to continue the trial. A study-specific risk assessment will also be performed prior to the start of the study by the study sponsor. The risk assessment will consider all aspects of the study and will be updated as required during the course of the study.
We do not expect participation to result in any additional burden on the participant. Participants will attend hospital for a duplex venous ultrasound scan 21 days after the procedure, and the researchers will offer reimbursement for travel. Participants will then be followed up remotely at 7 and 90 days after the procedure. Data can be provided by online survey, text or telephone depending on patient preference. Minimal data collection will occur at these follow-ups. Incidental findings may be identified during study assessments, such as the duplex ultrasound scan. Such findings will be reported to the local clinical team and to the participant’s GP.
Blood thinners are offered routinely to people who would be eligible to participate in this study. Possible complications of blood thinners are bleeding, allergy, rash and low numbers of platelets in the blood (platelets help the blood to clot). These are only the complications which could occur; we are not expecting them all to happen to every participant, and the majority of people do not have any complications. The risk of blood clots is higher in pregnant women. Pregnant women therefore should not take part in this study, and neither should women who plan to become pregnant during the 90 days of the study. Women who could become pregnant should use an effective method of contraception during the course of this study. Any woman who finds that she has become pregnant while taking part in the study should inform her research doctor as soon as possible.

Where is the study run from?
Imperial College London (UK)

When is the study starting and how long is it expected to run for?
February 2023 to August 2026

Who is funding the study?
Health Technology Assessment Programme (UK)

Who is the main contact?
Sarah Whittley, s.whittley@imperial.ac.uk

Contact information

Study information

Eligibility

Locations

Countries of recruitment

• England
• Northern Ireland
• United Kingdom
• Wales

Study participating centres

Sponsor information

Imperial College London
University/education

Room 4E 04, 4th Floor East Wing
Charing Cross Hospital
Fulham Palace Road
London
W6 8RF
England
United Kingdom

Phone	+44 (0)20 7594 8081
Email	r.ezra@imperial.ac.uk
Website	http://www.imperial.ac.uk/
"ROR"	https://ror.org/041kmwe10

Funders

Funder type

Government

Results and Publications

Study outputs

Additional files

ISRCTN18501431_PROTOCOL_V2.0_ 18Aug23.pdf

Editorial Notes

06/03/2025: The following changes were made to the trial record:
1. ClinicalTrials.gov number added.
2. The exclusion criteria were changed.
3. The plain English summary was updated to reflect these changes.
19/02/2024: Publication reference added.
15/01/2024: Internal review.
12/01/2024: The inclusion and exclusion criteria were updated.
04/01/2024: The recruitment start date was changed from 01/01/2024 to 15/01/2024.
04/10/2023: Internal review.
15/09/2023: The following changes were made to the study record:
1. The recruitment start date was changed from 31/08/2023 to 01/01/2024.
2. The recruitment end date was changed from 30/11/2025 to 31/03/2026.
3. Protocol uploaded.
4. Ethics approval details added.
15/09/2023: ISRCTN received notification of combined HRA/MHRA approval for this trial on 15/09/2023.
24/02/2023: Trial's existence confirmed by the HRA.