title: Prevalence of paediatric inflammatory bowel disease in Sweden: a nationwide population-based register study.
abstract: BACKGROUND
  We evaluated the impact of different case definition algorithms on the prevalence of paediatric inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC) and to compare the occurrence of certain diseases compared to matched controls.
  
  
  METHODS
  Paediatric patients (<18 years) were identified via ICD codes for UC and CD in Swedish registers between 1993 and 2010 (n = 1432). Prevalence was defined as ≥2 IBD-related visits. Prevalence of treated children in 2010 was defined as ≥2 IBD-related visits with one visit and ≥1 dispensed IBD-related drug prescription in 2010. To test the robustness of the estimates, prevalence was also calculated according to alternative case definitions. The presence of rheumatic, hepatobiliary, pancreatic, and dermatologic diseases were compared with age-/sex-/county-of-residence-matched general population controls.
  
  
  RESULTS
  The IBD prevalence was 75/100,000 (CD: 29/100,000; UC: 30/100,000; patients with IBD-U: 16/100,000). Prevalence of treated disease in 2010 was 62/100,000 (CD: 23/100,000; UC: 25/100,000; patients with IBD-U: 13/100,000). When age restrictions were employed, the prevalence estimate decreased (<17y: 61/100,000, <16y: 49/100,000 and <15y: 38/100,000). Compared to general population controls (n = 8583), children with IBD had a higher prevalence of dermatologic (4.7% vs. 0.6%), hepatobiliary (including primary sclerosing cholangitis) (5.5% vs. 0.1%), pancreatic (1.7% vs. 0%) and rheumatic diseases (7.2% vs. 1.2%; all P < 0.01).
  
  
  CONCLUSIONS
  The overall prevalence of paediatric IBD in Sweden was similar to that in earlier regional cohorts. IBD patients had a higher prevalence of comorbid conditions than matched general population controls.
authors.affiliation: Department of Paediatrics, Örebro University Hospital, Örebro, Sweden. jonasludvigsson@yahoo.com.|Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, SE-171 76, Stockholm, Sweden. jonasludvigsson@yahoo.com.
authors.forename: J F
authors.initials: JF
authors.lastname: Ludvigsson
authors.affiliation: Department of Medicine Solna, Clinical Epidemiology Unit, Karolinska Institutet, Stockholm, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Büsch
authors.affiliation: Department of Medicine Solna, Clinical Epidemiology Unit, Karolinska Institutet, Stockholm, Sweden.|Department of paediatric gastroenterology and nutrition, Sachs' Children and Youth Hospital, Stockholm, Sweden.
authors.forename: O
authors.initials: O
authors.lastname: Olén
authors.affiliation: Department of Medicine Solna, Clinical Epidemiology Unit, Karolinska Institutet, Stockholm, Sweden.|Department of Rheumatology, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Askling
authors.affiliation: Department of Medicine Solna, Clinical Epidemiology Unit, Karolinska Institutet, Stockholm, Sweden.
authors.forename: K E
authors.initials: KE
authors.lastname: Smedby
authors.affiliation: Department of Medicine Solna, Clinical Epidemiology Unit, Karolinska Institutet, Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Ekbom
authors.affiliation: Department of Paediatrics, Örebro University Hospital, Örebro, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Lindberg
authors.affiliation: Department of Medicine Solna, Clinical Epidemiology Unit, Karolinska Institutet, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Neovius
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003093:Colitis, Ulcerative / Q000453:epidemiology / Q000628:therapy; D015897:Comorbidity; D003424:Crohn Disease / Q000453:epidemiology / Q000628:therapy; D005260:Female; D006296:Health Services / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology* / Q000628:therapy; D008297:Male; D015995:Prevalence; D012042:Registries; D013548:Sweden / Q000453:epidemiology
keywords: Crohn’s disease; Inflammatory bowel disease; Paediatrics; Prevalence; Sweden; Ulcerative colitis