The development of postthrombotic syndrome in relationship to venous reflux and calf muscle pump dysfunction at 2 years after the onset of deep venous thrombosis

Objective: Postthrombotic syndrome (PTS) develops in 40% to 60% of patients with deep venous thrombosis. Factors that are important in the development of PTS include venous reflux, deep vein obstruction, and calf muscle pump dysfunction (CMD). Methods: Reflux and CMD in relationship to the severity of PTS were evaluated in a 2-year follow-up study of patients with acute deep venous thrombosis. Duplex scanning was used to measure reflux. The supine venous pump function test (SVPT) measures CMD with strain-gauge plethysmography. The base-line examination was performed within 1 to 5 days after diagnosis. The next examinations were scheduled at 3, 6, 12, and 24 months. Results: The study included 86 legs, and the 2-year follow-up period was completed for 70 legs. Significantly more reflux was found in previously thrombosed vein segments, with an odds ratio of 1.8 after 3 months, of 2.1 after 6 months, of 2.5 after 12 months, and of 3.2 after 24 months. Multiple regression results showed that the most important risk factor for early clinical signs of PTS was superficial reflex in months 3, 6, and 12 (P less than or equal to .02). Deep reflux did not have a synergistic relationship with superficial reflex in correlation with the clinical signs of PTS. The SVPT was not able to predict the development of PTS. Conclusion: More reflux develops in previously thrombosed vein segments. As early as after the third month, patients with superficial reflux have an increased risk of development of the first clinical signs of PTS. Within 2 years, the SVPT shows no relationship with clinical signs of PTS.