Funder
National Institute for Health Research (NIHR) – Health Technology Assessment (HTA).

Aim 
To establish whether in patients undergoing endovenous varicose vein procedures:

1. A single dose of pharmacological thromboprophylaxis decreases the risk of VTE
2. An extended course of pharmacological thromboprophylaxis further decreases the risk of VTE
3. Pharmacological thromboprophylaxis is associated with an increased rate of bleeding events
4. Providing pharmacological prophylaxis is cost effective
5. There is a signal to suggest the pharmacological agent used affects the rate of VTE

Design
Multi-centre, assessor-blind randomised controlled trial with intention-to-treat analysis.

Setting
Hospitals/clinics, including both NHS and private providers, delivering endovenous varicose vein procedures under local anaesthesia. Recruitment centres will need to have a pre-existing practice prior to the trial to prevent any learning curve effects.

Target population (n = 6,660):
Adults undergoing endovenous interventions for varicose veins under local anaesthesia.  

Inclusion/exclusion criteria

Inclusion criteria

• Adults (>18 years)
• Scheduled to undergo to undergo endovenous intervention of truncal varicose veins under local anaesthesia
• Treatment technologies including radiofrequency, laser, mechanochemical, foam sclerotherapy and cyanoacrylate glue

Exclusion criteria

• Clinical indication for anticoagulation
• Clinical contraindication to anticoagulation
• Previous personal or family history of VTE
• Thrombophilia
• Inability to provide informed consent or consent by proxy/consultee
• Female patients of childbearing age who have a positive pregnancy test
• A positive test for SARS-CoV2 <3 months of procedure*

*may change dependent upon national/local guidance

Outcomes

Primary Outcome
Imaging confirmed lower limb DVT with or without symptoms, or PE with symptoms within 90 days of varicose vein treatment.

Secondary outcomes

• Individual components of the composite outcome
• Quality of life as determined by the validated outcome
• Mortality
• Incremental cost-effectiveness ratio (ICER) – cost-effectiveness
  • Sub-group analyses of the following risk assessment tools: DHRA tool, Caprini score

Follow up
Participants will have a duplex ultrasound scan performed locally at 21 – 28 days post-procedure. Remote follow ups will be conducted centrally by telephone, online or SMS at 7- and 90-days post-procedure by the coordinating centre (Imperial College London).