ABSTRACT
OBJECTIVE: To assess absolute and relative risks of serious infections (resulting in inpatient care) in children with inflammatory bowel disease (IBD) compared with the general population. STUDY DESIGN: We identified children (<18 years of age) with a first diagnosis of IBD in the Swedish nationwide health registry (2002-2017; n = 5767) and individuals from the general population matched for sex, age, calendar year, and place of residence (reference group; n = 58 418). Hazard ratios (HRs) for serious infections were estimated using Cox regression separately in children with ulcerative colitis (n = 2287), Crohn's disease (n = 2365), and IBD unclassified (n = 1115). RESULTS: During 17 408 person-years of follow-up, 672 serious infections (38.6/1000 person-years) occurred among the children with IBD compared with 778 serious infections in the reference group (4.0/1000 person-years; adjusted HR (95% CI), 9.46 [8.53-10.5]). HRs were increased for children with ulcerative colitis 8.48 (7.21-9.98), Crohn's disease 9.30 (7.86-11.0), and IBD unclassified 12.1 (9.66-16.1). HRs were highest in the first year of follow-up (HR = 12.6 [10.7-14.9]), then decreasing to a 4.8-fold increased risk beyond 10 years of follow-up. Particularly high HRs were also seen in children with IBD undergoing surgery. Apart from a high relative risk of gastrointestinal infections resulting in hospitalization, children with IBD were also at an increased risk of opportunistic infections (HR = 11.8 [6.17-22.5]). CONCLUSIONS: Children with IBD have an increased risk of serious infection requiring hospitalization compared with the general population.