Around 45% of the UK population has varicose veins, and tens of thousands undergo endovenous treatment each year, yet doctors disagree on whether to give blood-thinning drugs to prevent dangerous clots afterwards. This trial will settle that debate. Venous thromboembolism—clots that can travel to the lungs—is a known complication of the procedure, but no high-quality evidence exists to guide whether a single dose of anticoagulant, or an extended course, actually reduces risk without causing bleeding. The researchers will randomise adults having endovenous therapy to compression alone, compression plus a single dose of low-molecular weight heparin, or compression plus a single dose followed by up to 14 days of additional anticoagulation. The primary outcome is imaging-confirmed deep vein thrombosis or symptomatic pulmonary embolism within 90 days. If the results show that one regimen safely prevents clots, it will directly update international clinical guidelines and change how thousands of patients are managed each year, reducing both harm and unnecessary drug use.
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Research question: What is the most clinical and cost effective thromboprophylaxis regimen following endovenous varicose vein treatments? Background: Varicose veins are common affecting 45% of the UK population. Endovenous therapy is the first-choice management in NICE guidelines, with 56-70,000 procedures performed across the NHS and private sector annually. Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), and endothermal heat-induced thrombosis are known complications of endovenous therapy and occur at a rate of up to 3.4%. VTE has negative consequences for patients, healthcare providers and society. Pharmacological thromboprophylaxis, peri-procedurally or extended duration post-operatively, is prescribed in attempt to reduce VTE. However, no high-quality evidence to support this practice exists. Despite this, 73% of practitioners use pharmacological thromboprophylaxis, 30% of whom use an extended duration, with the remaining 27% not offering pharmacological thromboprophylaxis. Pharmacological thromboprophylaxis may have clinical and cost benefit in preventing VTE, however, further evidence is needed. Aims and objectives: In line with the commissioning brief, aims are to establish whether: 1) patients undergoing endovenous varicose vein interventions benefit from a single dose of pharmacological thromboprophylaxis to prevent VTE 2) patients undergoing endovenous varicose vein interventions benefit from an extended course of pharmacological thromboprophylaxis to prevent VTE 3) patients receiving pharmacological thromboprophylaxis experience an increased rate of bleeding events 4) providing pharmacological thromboprophylaxis is cost effective 5) there is a signal to suggest the pharmacological agent used affects the rate of VTE Methods: Multi-centre, assessor-blind randomised controlled trial with a superiority comparison. 6660 participants will be randomised to one of three arms: 1. Compression therapy* alone 2. Compression therapy* + single dose of low-molecular weight heparin (LMWH) at time of procedure 3. Compression therapy* + single dose of LMWH at time of procedure + extended dose** anticoagulation with LMWH or Direct-Acting Oral Anticoagulants (DOAC) as per local preference *compression bandaging, stockings or compression wraps aligning with standard of care **between 7 and 14 days in duration Inclusion criteria encompasses adults undergoing endovenous therapy for truncal varicose veins under local anaesthesia. Exclusion criteria includes, but is not limited to, personal or family history of VTE, known thrombophilia, contraindication to anticoagulation or clinical indication for therapeutic anticoagulation. Primary outcome is imaging confirmed lower limb DVT with or without symptoms, or PE with symptoms <90 days from treatment. Timelines for delivery: Study duration: 39 months - 3m set-up, 27m recruitment, 3m follow-up, 6m close-down. Anticipated impact and dissemination: Findings will guide international clinical practice and stimulate key updates to international guidelines. Results will be published in high-impact journals alongside presentation at European and American vascular and haematology societies. This trial is supported by the following organisations who will play a key role in dissemination: Imperial College London, Hull York Medical School, NIHR, Thrombosis UK, Circulation Foundation, Lindsay Leg Club, Vascular All Party Parliamentary Group, VSGBI, and Royal Society of Medicine.
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