THRIVE Trial: Advancing Thromboprophylaxis in Superficial Venous Intervention

Superficial venous intervention has transformed the treatment of varicose veins, offering patients minimally invasive solutions with excellent short-term outcomes. Yet, despite technical advances, an important question remains unresolved: Should pharmacological thromboprophylaxis be routinely prescribed to prevent postoperative deep vein thrombosis (DVT)?

The THRIVE trial (THRomboprophylaxis In superficial endovenous interVEntion) is the first randomised controlled study designed to address this uncertainty.1 By generating robust clinical evidence, THRIVE has the potential to influence international practice and shape future guideline recommendations.

Varicose veins are common, affecting up to 45% of the UK population and are associated with reduced physical and mental health-related quality of life.2,3 Symptomatic varicose veins are now routinely treated with endovenous thermal ablation, non-thermal ablation or mechanochemical techniques.4 While effective, these procedures carry a recognised risk of venous thromboembolism (VTE).

To mitigate this risk, up to 73% of UK clinicians routinely prescribe pharmacological thromboprophylaxis, whereas others limit its use to patients considered high risk, and many prescribe none at all.5 Practice therefore varies considerably, both nationally and internationally.6 Guidelines similarly provide inconsistent recommendations, reflecting the limited availability of high-quality evidence.7,8 Although some studies suggest that pharmacological thromboprophylaxis may reduce the rate of postoperative DVT in this setting, there is currently no Grade A evidence to confirm this.1 The THRIVE trial has been designed to address this uncertainty by directly comparing outcomes in patients undergoing superficial endovenous intervention with and without prophylactic anticoagulation.9

THRIVE is a pragmatic, multicentre, randomised controlled trial sponsored by Imperial College London and funded by the National Institute for Health and Care Research (NIHR).

Randomisation is managed centrally using REDCap. All data are captured via REDCap and pseudonymised prior to analysis. At trial completion, anonymised datasets will also be shared with international collaborators to enable cost-effectiveness modelling.

If pharmacological thromboprophylaxis proves beneficial, it could become a new standard of care, improving patient safety and reducing the burden of DVT. If, on the other hand, it shows no benefit, the trial will provide reassurance that anticoagulation can be safely avoided, sparing patients unnecessary medication and reducing healthcare costs.

Either outcome will have significant implications. For clinicians, it will resolve longstanding uncertainty in practice. For patients, it will support transparent, evidence-based discussions about risks and benefits. And for policymakers, THRIVE will provide data to underpin consistent guideline recommendations across health systems.

As of September 2025, site setup is complete across 29 centres, and recruitment is actively underway. Interim analyses will be performed at predefined milestones, with recruitment due to end in March 2026. Updates will be shared through trial newsletters, academic conferences, and peer-reviewed publications.

The THRIVE trial represents a landmark step in addressing a critical gap in evidence for superficial venous intervention. By clarifying the role of pharmacological thromboprophylaxis, it has the potential to standardise practice, improve patient safety and inform international guidelines. As recruitment progresses, the study team looks forward to sharing findings that could reshape the care pathway for thousands of patients each year.

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