Acute prognostic factors for post-thrombotic syndrome in children with Limb DVT: A Bi-institutional cohort study

Background: Early identification of children with deep venous thrombosis (DVT) of the limb who are at heightened risk for post-thrombotic syndrome (PTS) is important in order to evaluate therapeutic interventions aimed at decreasing the risk and severity of PTS. Objective: We sought to evaluate acute prognostic factors for PTS in children following DVT of the limbs. Materials and Methods: In this bi-institutional mixed cohort study with prospective ascertainment of PTS using a validated pediatric instrument, we collected data on patient/thrombus characteristics, thrombophilia testing results, and outcomes in children (< 21 years at event) diagnosed with acute limb DVT at Rady Children's Hospital of San Diego and Children's Hospital Colorado. Results: Median age at presentation was 13 years (range, 0-18 years). Cumulative incidence (i.e. risk) of PTS was 23%, at a median follow-up duration of 33 months (range, 13.2-65 months). The presence of a lupus anticoagulant by dilute Russell Viper venom time (dRVVT) testing within two weeks of DVT diagnosis was associated with markedly increased odds of developing clinically-significant PTS (OR: 16.8, 95%CI 1.60-176.2; P = 0.02). The presence of an infectious or inflammatory condition at DVT presentation was neither associated with PTS risk nor dRVVT positivity. CONCLUSION: An acutely positive dRVVT following diagnosis of limb DVT appears to be a significant prognostic factor for development of clinically significant PTS in children. Larger collaborative cohort studies are required to substantiate these findings, evaluate other prognostic factors, and determine whether the present association is modulated by persistent dRVVT positivity or beta-2-glycoprotein-I dependence.