Recurrent thrombosis and major bleeding in children treated for VTE.

Risk factors for recurrent venous thromboembolism (VTE) in children are poorly understood, and concerns remain about the risks of anticoagulant therapy in children. This single-center cohort with nested case-control study aimed to determine the incidence rate of recurrent thrombosis and associated risk factors and the incidence of major bleeding in children with VTE on therapeutic anticoagulation. We identified 632 patients managed for VTE between 1 January 2015 and 31 December 2022. The recurrence rate of VTE was 13.7 per 100 person-years. Univariate analysis showed the presence of a central venous catheter (CVC; P = .02), inflammatory bowel disease (IBD; P = .02), and intestinal failure (P = .03) were significant risk factors for recurrent VTE. In multivariate logistic regression, significant risk factors for recurrence were anatomic venous abnormality (odds ratio [OR], 2.8; 95% confidence interval [CI], 1.37-5.59), presence of a CVC (OR, 2.0; 95% CI, 1.21-3.26), and IBD (OR, 3; 95% CI, 1.18-7.98). Major bleeding on anticoagulation occurred at a rate of 2.2 per 100 person-years. These data demonstrate that this heterogeneous cohort of children had a high risk of VTE recurrence. The overall major bleeding risk with anticoagulation was low. Although each patient with VTE needs to be considered individually, these data support the view that perceived bleeding risk should generally not be a major barrier to anticoagulation in the pediatric setting. Moreover, secondary or extended anticoagulation may be considered in children at high risk for recurrence.