RESUMO
OBJECTIVE: To study whether stopping elastic compression stockings (ECS) after 12 months is non-inferior to continuing them for 24 months after proximal deep venous thrombosis. DESIGN: Multicentre single blind non-inferiority randomised controlled trial. SETTING: Outpatient clinics in eight teaching hospitals in the Netherlands, including one university medical centre. PARTICIPANTS: Patients compliant with compression therapy for 12 months after symptomatic, ultrasound proven proximal deep venous thrombosis of the leg. INTERVENTIONS: Continuation or cessation of ECS 12 months after deep venous thrombosis. MAIN OUTCOME MEASURES: The primary outcome was the incidence of post-thrombotic syndrome 24 months after diagnosis of deep venous thrombosis, as assessed by the standardised Villalta scale in an intention to treat analysis. The predefined non-inferiority margin was 10%. The main secondary outcome was quality of life (VEINES-QOL/Sym). RESULTS: 518 patients compliant with ECS and free of post-thrombotic syndrome were randomised one year after diagnosis of deep venous thrombosis to stop or continue ECS therapy for another year. In the stop-ECS group, 51 of 256 patients developed post-thrombotic syndrome, with an incidence of 19.9% (95% confidence interval 16% to 24%). In the continue-ECS group, 34 of 262 patients developed post-thrombotic syndrome (incidence 13.0%, 9.9% to 17%), of whom 85% used ECS six or seven days a week during the study period, for an absolute difference of 6.9% (95% confidence interval upper limit 12.3%). Because the upper limit of the 95% confidence interval exceeds the predefined margin of 10%, non-inferiority was not reached. The number needed to treat to prevent one case of post-thrombotic syndrome by continuing ECS was 14 (95% confidence interval lower limit 8). Quality of life did not differ between the two groups. CONCLUSION: Stopping ECS after one year in compliant patients with proximal deep venous thrombosis seemed not to be non-inferior to continuing ECS therapy for two years in this non-inferiority trial. TRIAL REGISTRATION: Netherlands Trial Register NTR1442.