Safety and utilization of influenza immunization in children with inflammatory bowel disease.

OBJECTIVE Influenza immunization is recommended for children with IBD, however safety concerns may limit uptake. This study assessed whether immunization was associated with adverse events in IBD patients using a population-based database of children with IBD. METHODS All children <19 years diagnosed with IBD in Ontario, Canada between 1999-2009 were identified using health administrative data, and matched to non-IBD controls. Self-controlled case series (SCCS) analyses determined health services event rates (outpatient visits, hospitalizations and emergency visits) in any 2-week risk period to 180 days post-immunization compared to a no-risk control period. Relative incidence (RI) was calculated for overall and IBD-related events and rates were compared between IBD cases and controls using relative incidence ratios (RIR). RESULTS A total of 4916 IBD patients were matched to 21 686 controls. IBD patients were more likely to have received immunization than controls (25.3% vs 13.2%, P < .001). No increased event rates existed in IBD cases during risk periods (pooled RI 0.95, 95% CI 0.84-1.07), including hospitalizations and emergency visits. There was a slightly higher event rate in IBD cases versus controls for days 3-14 (RIR 1.60, 95% CI 1.05-2.44, P = .03). IBD-related visit rates were lower in risk periods compared to control period (pooled RI 0.81, 95% CI 0.68-0.96). CONCLUSIONS There was no increase in health services use in the post-vaccine risk period in IBD patients, and there was evidence for a protective effect of influenza immunization against IBD-related health services use. Influenza immunization is safe in children with IBD and should be encouraged to improve poor coverage rates.