NCT07432529

Design and Rationale of the COLT Study

Design and Rationale of the COLT Study: a Multicentre, Randomised, Double-blind, Placebo-controlled Trial of COLchicine as Adjunctive Therapy to Standard Anticoagulation in Acute Proximal Deep Vein Thrombosis of the Lower Limbs

• Status: Not Yet Recruiting
• Phase: Phase 3
• Study type: Interventional
• Enrollment: 940 (estimated)
• Sponsor: Azienda Sanitaria Locale ASL 6, Livorno · Other Government
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

Deep vein thrombosis (DVT) is a condition in which a blood clot forms in the deep veins of the leg and can lead to long-term problems such as leg pain, swelling, and reduced quality of life. Standard treatment with blood-thinning medication lowers the risk of complications, but some patients still develop long-term damage to the veins. Inflammation is thought to play an important role in these complications. This study will evaluate whether adding colchicine, an anti-inflammatory medication already used for other conditions, to standard anticoagulant therapy can improve outcomes in patients with acute DVT. Participants will be randomly assigned to receive either colchicine or a placebo, in addition to usual blood-thinning treatment, and will be followed for one year. The main goal of the study is to determine whether colchicine reduces the risk of developing long-term vein problems after DVT. The study will also assess the risk of new blood clots, vein recovery, quality of life, and the safety of colchicine treatment.

Detailed description

Deep vein thrombosis (DVT) of the lower limbs is a serious condition in which a blood clot forms in the deep veins of the leg. DVT can lead to long-term complications such as post-thrombotic syndrome (PTS), chronic leg swelling, pain, skin changes, and impaired quality of life. Standard treatment with anticoagulants helps prevent clot progression and reduces the risk of recurrent venous thromboembolism (VTE), but many patients still develop long-term vein damage. Inflammation is believed to play a key role in clot development, vein-wall injury, and delayed resolution of DVT. Colchicine is an anti-inflammatory medication that has been widely used in other cardiovascular and inflammatory conditions and has a favorable safety profile when used in low doses. Preliminary studies suggest colchicine may help reduce inflammation associated with DVT and promote vein recovery. The COLT-DVT study is a multicenter, randomized, double-blind, placebo-controlled clinical trial being conducted in Italy. The study will enroll approximately 940 adult patients with a first episode of acute proximal DVT of the lower limbs. Participants will be randomly assigned in a 1:1 ratio to receive either low-dose colchicine or a matching placebo, in addition to standard anticoagulant therapy. Colchicine treatment will be administered as 0.5 mg twice daily for the first month, followed by 0.5 mg once daily for the subsequent five months. Participants will be followed for a total of 12 months. The main goal of the study is to determine whether the addition of colchicine reduces the incidence of post-thrombotic syndrome one year after DVT. Secondary objectives include assessing recurrent VTE, vein reopening and valve function via duplex ultrasound, health-related quality of life using validated questionnaires, and the safety and tolerability of colchicine treatment. This study aims to provide new evidence on whether targeting inflammation in DVT can improve patient outcomes, reduce long-term complications, and potentially change standard care practices. Participants will be closely monitored for safety, and any side effects will be recorded and managed according to standard clinical practice.

Conditions

• Venous Thrombosis Deep (Limbs)
• Post-thrombotic Syndrome
• Venous Thromboembolism (VTE)
• Venous Insufficiency

Interventions

Type	Name	Description
DRUG	Colchicine 0.5 MG Oral Tablet	Low-dose colchicine added to standard anticoagulant therapy for acute proximal deep vein thrombosis. Colchicine is administered 0.5 mg twice daily for the first month, then 0.5 mg once daily for the next five months. Participants are monitored for post-thrombotic syndrome, recurrent venous thromboembolism, vein recanalization, quality of life, and safety over 12 months.
DRUG	Placebo	Matching placebo administered alongside standard anticoagulant therapy on the same schedule as colchicine. Participants are monitored for the same outcomes and safety measures.

Timeline

• Start date: 2026-06-01
• Primary completion: 2027-06-01
• Completion: 2027-06-01
• First posted: 2026-02-25
• Last updated: 2026-02-25