Low‐dose warfarin for the prevention of central line‐associated thromboses in children with malignancies—a randomized, controlled study

BACKGROUND: Central venous lines (CVLs) are essential in the care of children with malignancies, but are associated with venous thromboembolism (VTE) and infections. Effective and safe prophylactic approaches are deficient. AIM: To perform a study of adjusted low-dose warfarin for the prevention of CVL-related VTE in children with malignancies. METHODS: Children with newly diagnosed cancer, a CVL in a jugular vein and an expected treatment period of over 6 mo were eligible for the study. Participants were randomized to low-dose warfarin, with intended international normalized ratio (INR) 1.3-1.9, or to a control group. Primary outcome was VTE in a jugular vein diagnosed by ultrasonography at 1, 3 and 6 mo after inclusion. Secondary outcome was CVL-related infections, mainly measured as days on antibiotics or positive blood cultures. RESULTS: The study enrolled 73 children, and 62 completed it fully. Asymptomatic CVL-related VTE was frequent (42%), but often transient. Regardless of severity, timing and duration, CVL-related VTE was equally frequent among children on warfarin as compared to controls (p=0.44). Low-dose warfarin (p=0.59) or jugular CVL-related VTE (p=0.91) did not have any impact on days on antibiotics, but we observed a tendency towards an association between CVL-related VTE and positive blood cultures (p=0.15). CONCLUSION: Our randomized study of low-dose oral anticoagulation for the prevention of CVL-related asymptomatic VTE in children with cancer did not show any benefit of warfarin adjusted to maintain INR between 1.3 and 1.9.