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21/590 Thromboprophylaxis following endovenous treatment for people with varicose veins commissioning brief



The aim of the HTA Programme is to ensure that high quality research information on the clinical effectiveness, cost-effectiveness and broader impact of healthcare treatments and tests is produced in the most efficient way for those who plan, provide or receive care from NHS and social care services. The commissioned workstream invites applications in response to calls for research on specific questions which have been identified and prioritised for their importance to the NHS, patients and social care.

Research question

What is the most clinical and cost effective thromboprophylaxis regime following endovenous treatment for varicose veins?

  1. Intervention: Chemical (pharmaceutical) thromboprophylaxis pre procedure and one week after the procedure, and mechanical thromboprophylaxis as per routine care.
  2. Patient group: Adults undergoing endovenous treatment for symptomatic varicose veins.
    Applications are encouraged which include recruitment from geographic populations with high disease burden which have been historically underserved by research activity in this field.
  3. Setting: Any appropriate centre.
  4. Comparator: Mechanical thromboprophylaxis as per routine care.
  5. Study design: A randomised controlled trial with an internal pilot phase to test key trial processes such as recruitment and adherence. Clear stop/go criteria should be provided to inform progression from pilot to full trial. Applicants should give consideration to the use of appropriate and efficient trial designs.
  6. Important outcomes: Venous thromboembolism.
  7. Other outcomes: Type and location of venous thromboembolism, bleeding complications, pain, quality of life, recovery time, cost-effectiveness, patient acceptability, efficacy of procedure. Existing Core Outcomes should be included amongst the list of outcomes unless a good rationale is provided to do otherwise. Applicants are encouraged to report recruitment and findings disaggregated by sex (and other demographic factors where relevant).
  8. Minimum duration of follow-up: Applicants to define and justify.
  9. Longer-term follow-up: If appropriate, researchers should consider obtaining consent to allow potential future follow-up through efficient means (such as routine data) as part of a separately funded study.


Varicose veins are swollen and enlarged veins that cause pain and discomfort and are most often located on the legs and feet. They can be treated endovenously (inside the vein) with interventions that use heat, glue, or chemical foam to seal the veins or by surgically removing the veins. A significant complication of varicose veins (and the endovenous treatment for them) is the formation of blood clots in the veins (known as venous thromboembolism; VTE).

The prevention of blood clots (thromboprophylaxis) can help reduce the incidence of VTE in patients and the subsequent severe complications of VTE such as leg ulcers. Thromboprophylaxis can be mechanical, e.g., using graduated compression stockings (GCS), or chemical (pharmaceutical), e.g., heparin and other drugs. GCS can be uncomfortable for patients to wear for long periods of time. Chemical prophylaxis has been suggested as an adjunct to GCS, however there is limited evidence regarding its benefits and risks, highlighting a need for comparative research.

SIGN guidance on the prevention and management of VTE suggested several pharmaceutical treatment options that warrant further research, and the Royal College of Surgeons has suggested this topic for prioritisation.

Further studies are needed to establish the clinical and cost-effectiveness of chemical thromboprophylaxis to help guide UK clinical practice. The HTA Programme therefore wishes to commission the trial outlined above.

Additional commissioning brief background information

A background document is available that provides further information to support applicants for this call. It is intended to summarise what prompted the call and the existing evidence base, including relevant work from the HTA and wider NIHR research portfolio. It was researched and written on the basis of information from a search of relevant sources and databases, and in consultation with a number of experts in the field. If you would like a copy, please email

Making an application

If you wish to submit a Stage 1 application for this call, the online application form can be found on the funding opportunities page. To select this call, use the filters on the right of the screen or search using the call name and/or number.

Your application must be submitted on-line no later than 1pm on the 30 March 2022. Applications will be considered by the HTA Funding Committee at its meeting in May 2022.

Guidance notes and supporting information for HTA Programme applications are available.

Important: Shortlisted Stage 1 applicants will be given eight weeks to submit a Stage 2 application. The Stage 2 application will be considered at the Funding Committee in September 2022.

Applications received electronically after 1300 hours on the due date will not be considered.

For commissioned topics, the Programme strongly discourages the practice of the same co-applicant joining more than one competing team. There may be unusual circumstances where the same person could be included on more than on application eg a lead from a named charity or a unique national expert in a condition.

For such exceptions (i) each application needs to state the case as to why the same person is included (ii) the shared co-applicant should not divulge application details between teams and (iii) both teams should acknowledge in their application that they are aware that one of their co-applicants is part of a competing application and that study details have not been shared.

Should you have any queries please contact us by email: