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Inflammatory bowel disease increases the risk of venous thromboembolism in children: a population-based matched cohort study

Kuenzig ME, Bitton A, Carroll MW, Kaplan GG, Otley AR, Singh H, Nguyen GC, Griffiths AM, Stukel TA, Targownik LE, Jones JL, Murthy SK, McCurdy JD, Bernstein CN, Lix LM, Peña-Sánchez JN, Mack DR, Jacobson K, El-Matary W, Dummer TJB, Fung SG, Spruin S, Nugent Z, Tanyingoh D, Cui Y, Filliter C, Coward S, Siddiq S, Benchimol EI; Canadian Gastro-Intestinal Epidemiology Consortium. J Crohns Colitis. 2021; 15(12):2031-40. Epub 2021 Jun 27. DOI:

Background and Aims — Although venous thromboembolism (VTE) is a well-known complication of inflammatory bowel disease (IBD) in adults, limited data exist on the risk in children. We report the incidence of VTE among children with and without IBD.

Methods — We conducted a matched cohort study within a distributed network of population-based Canadian provincial health administrative databases. Children diagnosed with IBD <16 years were identified using validated algorithms from administrative data in Alberta, Manitoba, Nova Scotia, Ontario, and Québec and compared to age- and sex-matched children without IBD. Hospitalizations for VTE within five years of IBD diagnosis were identified. Generalized linear mixed-effects models were used to pool province-specific incidence rates and incidence rate ratios (IRR) with 95% confidence intervals (CI). Hazard ratios (HR) from Cox proportional hazards models were pooled with fixed-effects meta-analysis.

Results — The five-year incidence of VTE among 3593 children with IBD was 31.2 (95%CI 23.7-41.0) per 10,000 person-years (PY) compared to 0.8 (95%CI 0.4-1.7) per 10,000 PY among 16,289 children without IBD (unadjusted IRR 38.84, 95%CI 16.59-90.83; adjusted HR 22.91, 95%CI 11.50-45.63). VTE was less common in Crohn's disease than ulcerative colitis (unadjusted IRR 0.47, 95%CI 0.27-0.83; adjusted HR 0.52, 95%CI 0.29-0.94). Findings were similar for deep vein thrombosis (DVT) and pulmonary embolism (PE) when comparing children with and without IBD.

Conclusions — The risk of VTE is much higher in children with IBD than controls without IBD. While the absolute risk is low, we found a higher incidence rate than previously described in the pediatric literature.

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