A randomized trial evaluated the effect of compression stockings in patients with symptomatic proximal deep-vein thrombosis. The study included 194 patients with a first episode of venogram-proven proximal deep-vein thrombosis, randomly assigned to either compression stockings or no stockings. The primary outcome was the cumulative incidence of mild-to-moderate post-thrombotic syndrome (PTS), defined as a score of ≥3 plus one clinical sign. PTS occurred in 20% of the stocking group and 47% of the control group (p<0.001). Severe PTS (score ≥4) occurred in 11% of the stocking group and 23% of the control group (p<0.001). The use of sized-to-fit compression stockings reduced the incidence of PTS by about 50%. Most cases of PTS occurred within the first 24 months of the acute thrombotic event. The study found that about 60% of patients with a first episode of proximal deep-vein thrombosis develop PTS within 2 years. Compression stockings did not affect the rate of recurrent venous thrombosis, suggesting different mechanisms for recurrence and PTS. The study concluded that compression stockings reduce the risk of PTS by about 50%, and that they should be worn for at least 2 years to achieve the observed preventive effect. The findings suggest that PTS is more common than previously thought and that compression stockings may be an effective preventive measure.A randomized trial evaluated the effect of compression stockings in patients with symptomatic proximal deep-vein thrombosis. The study included 194 patients with a first episode of venogram-proven proximal deep-vein thrombosis, randomly assigned to either compression stockings or no stockings. The primary outcome was the cumulative incidence of mild-to-moderate post-thrombotic syndrome (PTS), defined as a score of ≥3 plus one clinical sign. PTS occurred in 20% of the stocking group and 47% of the control group (p<0.001). Severe PTS (score ≥4) occurred in 11% of the stocking group and 23% of the control group (p<0.001). The use of sized-to-fit compression stockings reduced the incidence of PTS by about 50%. Most cases of PTS occurred within the first 24 months of the acute thrombotic event. The study found that about 60% of patients with a first episode of proximal deep-vein thrombosis develop PTS within 2 years. Compression stockings did not affect the rate of recurrent venous thrombosis, suggesting different mechanisms for recurrence and PTS. The study concluded that compression stockings reduce the risk of PTS by about 50%, and that they should be worn for at least 2 years to achieve the observed preventive effect. The findings suggest that PTS is more common than previously thought and that compression stockings may be an effective preventive measure.