Background and purpose: Most randomized controlled trials of venous thromboembolism prophylaxis have focused on reduction of deep vein thrombosis, predominantly asymptomatic deep vein thrombosis, detected on imaging. We aimed to estimate the effects of graduated compression stockings on venous thromboembolism events, survival, and functional status at 6 months after stroke.
Methods: The CLOTS Trials adopted an international multicentre, parallel group design, with central randomization and a 1:1 treatment allocation. In CLOTS Trial 1, 2518 immobile stroke patients were allocated thigh-length graduated compression stockings or not, and in CLOTS trial 2, 3014 to thigh-length or below-knee graduated compression stockings. We measured vital status, Oxford Handicap Scale, and quality of life (EQ5D-3 L) at 6 months.
Results: We compared survival in patients enrolled in Trials 1 and 2 with a Cox proportional hazards model, including variables included in our minimization algorithm. In both trials, allocation to thigh-length graduated compression stockings was associated with a very slight, but nonsignificant, increased hazard of death in the first 6 months (Trial 1: hazard ratio, 1.087; 95% confidence interval, 0.913-1.295; and Trial 2: hazard ratio, 1.037; 95% confidence interval, 0.892-1.205). There were no statistically significant differences in venous thromboembolism events, Oxford Handicap Scale, or EQ5D-3 L between the treatment groups in CLOTS Trials 1 or 2.
Conclusions: Although underpowered to detect clinically important effects on long-term outcomes, our results effectively exclude a >10% relative reduction in the hazard of death within 6 months associated with the use of thigh-length stockings. No other long-term benefits were apparent.