title: Safety and utilization of influenza immunization in children with inflammatory bowel disease.
abstract: 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.
authors: Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada. ebenchimol@cheo.on.ca
authors: Eric I
authors: EI
authors: Benchimol
authors: Steven
authors: S
authors: Hawken
authors: Jeffrey C
authors: JC
authors: Kwong
authors: Kumanan
authors: K
authors: Wilson
mesh_terms: D000293:Adolescent; D002170:Canada / Q000453:epidemiology; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006296:Health Services / Q000706:statistics & numerical data; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D015212:Inflammatory Bowel Diseases / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male
chemical_list: D007252:Influenza Vaccines
keywords: epidemiology; health administrative data; inflammatory bowel diseases; influenza vaccines; pediatrics; seasonal influenza; vaccine safety