The incidence and characteristics of venous thromboembolisms in paediatric-onset inflammatory bowel disease; a prospective international cohort study based on the PIBD-SETQuality Safety Registry.

BACKGROUND & AIMS: Guidelines regarding thromboprophylaxis for venous thromboembolisms (VTE) in children with inflammatory bowel disease (IBD) are based on limited paediatric evidence. We aimed to prospectively assess the incidence of VTE in paediatric-onset IBD (PIBD), characterize PIBD patients with VTE, and identify potential IBD-related risk factors. METHODS: From October 2016 till September 2020, paediatric gastroenterologists prospectively replied to the international Safety Registry, monthly indicating whether they had observed a VTE case in a patient <19 years with IBD. IBD details (type, Paris classification, clinical and biochemical disease activity, treatment) and VTE details (type, location, treatment, outcome) were collected. To estimate the VTE incidence, participants annually reported the number of PIBD patients, data source and catchment area of their center. A systematic literature review and meta-analysis was performed to calculate the VTE incidence in the general paediatric population. RESULTS: Participation of 129 PIBD centers resulted in coverage of 24,802 PIBD patients. Twenty cases of VTE were identified (30% Crohn's disease). The VTE incidence was 3.72 [95%CI 2.27 - 5.74] per 10,000 person-years, 14-fold higher than in the general paediatric population (0.27 [95%CI 0.18-0.38], p