Factors predicting development of post-thrombotic syndrome in patients with a first episode of deep vein thrombosis: preliminary report.

Objective: To investigate the indicative parameters reflecting the progression of post-thrombotic syndrome (PTS) in patients with a first episode of deep vein thrombosis (DVT).

Design And Methods: The patients' initial risk factors were assessed at presentation. Venous occlusion, and reflux and reflux parameters were evaluated at 6 months using venous duplex scanning. Near-infrared spectroscopy (NIRS) was also used to measure calf muscle deoxygenated haemoglobin levels at 6 months. Clinical manifestations were categorised using the clinical, etiologic, anatomic and pathophysiologic (CEAP) classification for chronic venous insufficiency (CVI), and the patients were divided into those having no PTS (C(0-3S),E(s),A(s,d,p),P(r,o)) and those having PTS (C(4-6S),E(s),A(s,d,p),P(r,o)).

Results: Of the 121 patients evaluated, 25 (21%) developed PTS with a mean follow-up period of 66 months. At initial presentation, ilio-femoral DVT (odds ratio (OR) 3.4, 95% confidence interval (CI) 1.4-8.6) was associated with development of PTS. At 6 months, venous occlusion combined with reflux (OR 4.4, 95% CI 2.9-20.7), peak reflux velocity >29.7 cm s(-1) (OR 13.7, 95% CI 4.1-45.7) and mean reflux velocity >8.6 cm s(-1) (OR 4.4, 95% CI 1.5-12.9) in the popliteal vein detected by duplex scanning were strong predictors of PTS. NIRS-derived retention index >3.5 was the strongest predictor of PTS at 6 months (OR 67.4, 95% CI 14.3-318.1).

Conclusions: Ilio-femoral DVT is associated with the development of PTS at initial presentation. By contrast, occlusion and reflux, high reflux velocity in the popliteal vein and increased NIRS-derived retention index are important time-course predictors of PTS progression.