title: Epidemiology of coeliac disease and comorbidity in Norwegian children.
abstract: OBJECTIVE
  The aim of this study was to describe the occurrence of clinically diagnosed coeliac disease in children ages 0 to 12 years in Norway, including regional variation and coexisting type 1 diabetes mellitus, thyroid disease, and Down syndrome.
  
  
  METHODS
  The Norwegian Patient Register (NPR) contains individual-level hospital data from 2008 onward. Small-bowel biopsies for establishing the coeliac disease diagnosis are only performed at public hospitals reporting to the NPR. Data on all hospital contacts during 2008-2011 when a diagnosis of coeliac disease was registered were retrieved from the NPR for patients born between 1999 and 2011, allowing estimation of the proportion registered with coeliac disease at ages 0 to 12 years in a cohort study.
  
  
  RESULTS
  A total of 3006 individuals (58.2% girls) were recorded as having coeliac disease among 797,360 children, corresponding to a proportion of 3.8/1000 (95% confidence interval [CI] 3.7-3.9/1000) children, 4.5 (CI 4.3-4.7) among girls and 3.1 (CI 2.9-3.3/1000) among boys (P < 0.001). The proportion increased with age up to approximately 6 years and was 5.0/1000 (CI 4.5-5.6) at the age of 12 years, and was slightly higher in the south/west (3.9/1000) as compared to the middle/north (3.5/1000) regions of Norway (P = 0.013). A total of 214 of 3006 (7.1%) patients with coeliac disease were registered with coexisting conditions: type 1 diabetes mellitus (n = 142, 4.7%), Down syndrome (n = 47, 1.6%), or thyroid disease (n = 41, 1.4%).
  
  
  CONCLUSIONS
  In this first nationwide study of clinically diagnosed coeliac disease in Norwegian children, we found a high occurrence, comparable with that in Sweden. Comorbidity was common, but routine screening of high-risk groups contributed to a limited number of cases.
authors.affiliation: *Norwegian Institute of Public Health, Oslo, Norway, and Østfold Hospital Trust, Fredrikstad, Norway †Norwegian Directorate of Health and Norwegian Patient Register, Trondheim ‡Norwegian Institute of Public Health §Norwegian Institute of Public Health, Oslo, Norway.
authors.forename: Ketil
authors.initials: K
authors.lastname: Størdal
authors.forename: Inger Johanne
authors.initials: IJ
authors.lastname: Bakken
authors.forename: Pål
authors.initials: P
authors.lastname: Surén
authors.forename: Lars C
authors.initials: LC
authors.lastname: Stene
mesh_terms: D000367:Age Factors; D002446:Celiac Disease / Q000150:complications / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000453:epidemiology*; D004314:Down Syndrome / Q000150:complications / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009664:Norway / Q000453:epidemiology; D013959:Thyroid Diseases / Q000150:complications / Q000453:epidemiology*