title: Frequency of indeterminate colitis in children and adults with IBD - a metaanalysis.
abstract: BACKGROUND
  Indeterminate colitis (IC) remains an enigmatic inflammatory bowel disease (IBD) phenotype. It is currently not clear whether it constitutes merely a problem of terminology, classification, or possibly an early stage of IBD distinct from Crohn's disease (CD) and ulcerative colitis (UC).
  
  
  METHODS
  We analysed epidemiological data of studies comparing IC, UC and CD. We selected 14 studies investigating paediatric patients (10 prospective and 4 retrospective) and 18 studies investigating adult IBD patients (11 prospective and 7 retrospective) for this analysis.
  
  
  RESULTS
  Compared to adults (n=15,776) the frequency of IC is higher in children (n=6262) (children 12.7% versus adults 6.0%, p<0.0001). This difference between children and adults has been detected irrespective whether prospective or retrospective studies were selected. In both, children and adults IC was more frequent in prospective studies compared to retrospective studies (children p=0.0004; adults p=0.0024).
  
  
  CONCLUSIONS
  IC has been detected in a substantial proportion of paediatric patients with IBD. IC is more frequently found in children compared to adults. Further studies are required to clarify whether IC represents an IBD phenotype associated with childhood disease onset or whether the high IC frequency is due to difficulties in establishing a UC or CD diagnosis.
authors.affiliation: University Children's Hospital, Section of Paediatric Gastroenterology, University of Leipzig, Liebigstr. 20a, 04305 Leipzig, Germany.
authors.forename: Freerk
authors.initials: F
authors.lastname: Prenzel
authors.forename: Holm H
authors.initials: HH
authors.lastname: Uhlig