Very long–term risk of moderate-to-severe postthrombotic syndrome after deep vein thrombosis

Postthrombotic syndrome (PTS) refers to manifestations of chronic venous insufficiency after a deep vein thrombosis (DVT). The risk of developing moderate-to-severe PTS in the very long term is largely unknown and particularly in case of distal DVT. Furthermore, the impact of DVT vs other causes of chronic venous insufficiency on long-term manifestations of PTS is also unknown. To assess the very long–term risk of moderate-to-severe PTS after DVT and the role that DVT plays in PTS symptoms. Patients with lower-limb DVT enrolled in the multicenter Optimisation de l’interrogatoire dans l’evaluation du risque thromboembolique veineux (OPTIMEV) study underwent a very long–term telephone follow-up. We assessed i) the proportion of moderate-to-severe PTS (assessed with the patient-reported Villalta score) according to DVT extent and ii) the population attributable fraction that DVT plays in patients’ moderate-to-severe PTS manifestations. Fourteen years after DVT, moderate-to-severe PTS developed in 35 of 185 patients with distal DVT (18.9%; 95% CI, 13.5%-25.3%), 11 of 47 patients with popliteal DVT (23.4%; 95% CI, 12.3%-38.0%), and 27 of 74 patients with iliofemoral DVT (36.5%; 95% CI, 25.6%-48.5%). The population attributable fraction of DVT in moderate-to-severe symptoms of PTS was 25.7% (−18.1% to 53.3%) in patients with distal DVT, 27.3% (−63.7% to 67.7%) in patients with popliteal DVT, and 43.1% (+0.7%-67.4%) in patients with iliofemoral DVT. In the very long term after DVT, a quarter of patients have moderate-to-severe PTS manifestations. However, the impact of the DVT on these manifestations appears nonpredominant and varies according to DVT extent. Distal DVT does not significantly increase the risk of developing moderate-to-severe PTS.