Clinical outcomes following catheter-related venous thrombo-embolism among children with acute lymphoblastic leukemia.

Venous thrombo-embolism (VTE) occurs in 10-15% of pediatric patients with acute lymphoblastic leukemia (ALL), yet the optimal duration of anticoagulation remains unclear. In this retrospective multi-center cohort study, we reported the clinical outcomes of pediatric patients treated for ALL with a history of central venous catheter (CVC)-related VTE and compared outcomes based on duration of anticoagulation. Patients aged 1-21 years old with newly-diagnosed ALL (2010-2023), receiving asparaginase-containing chemotherapy, experiencing a radiologically-proven CVC-related VTE requiring medical intervention, were included. Cumulative incidence and 95% confidence interval (CI) were estimated for VTE progression/recurrence and clinically relevant bleeding. Cox proportional hazard models were performed to compare clinical outcomes based on anticoagulation duration, categorized as a) asparaginase-based (following a 6-week course of anticoagulation, until the end of asparaginase' expected effects or earlier) or extended (later than asparaginase's expected effects), and b) before vs. after CVC removal. We included 106 patients (median age: 10 years, 59% male). Overall, 22 patients sustained a VTE progression/recurrence (cumulative incidence: 22%, 95% CI: 14-30%). Most progression/recurrences occurred while patients were still on anticoagulation, at a median of 54 days after index VTE. Duration of anticoagulation was not associated with VTE progression/recurrence (extended vs. asparaginase-based: HR = 1.49, 95%CI: 0.60-3.69, p = 0.392; after vs. before CVC removal: HR = 1.36, 95% CI: 0.49-3.74, p = 0.552). Clinically relevant bleeding occurred in 11/106 patients (cumulative incidence: 12%, 95% CI: 6-19%) and was not associated with anticoagulation duration. In summary, VTE progression/recurrence was common in pediatric patients with ALL. Further investigation into alternative approaches to reduce VTE progression/recurrence is warranted.