title: The importance of disease prevalence in assessing the diagnostic value of a test: endoscopic markers in celiac disease.
abstract: OBJECTIVE
  We evaluated the diagnostic variability and reproducibility of endoscopic signs in two populations with a different pretest likelihood of celiac disease (CD).
  
  
  METHODS
  We recruited 289 CD patients (both adults and children) in a multicenter prospective study. Group 1 (high risk) included 111 patients referred for positive serology. Group 2 (low risk) included 178 unselected patients. Mosaic pattern, reduction/loss of Kerckring's folds, scalloping of the valvulae conniventes and a nodular pattern were the endoscopic findings looked for in the duodenum.
  
  
  RESULTS
  In group 1, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of endoscopic findings were 100, 84.6, 94.2 and 100% in adults, and 86.8, 9.1, 82.1 and 12.5% in children. In group 2, the sensitivity, specificity, PPV and NPV of endoscopic findings were 33.3, 91.4, 7.7 and 98.5% in adults, and noncalculable, 78.3, 0.0 and 100% in children. Comparing group 1 and group 2, there was a statistically significant difference in sensitivity and PPV in adults, and in specificity, PPV and NPV in children. Concerning the reproducibility of endoscopic findings, a wide variability of κ values was found.
  
  
  CONCLUSIONS
  Endoscopic signs have low reproducibility for CD, and their diagnostic value in selecting patients for multiple intestinal biopsies is unacceptable, especially in populations with low disease prevalence.
authors.affiliation: Cystic Fibrosis and Pediatric Gastroenterology Unit, University Hospital 'G. Martino', Messina, Italy.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Pellegrino
authors.forename: Federica
authors.initials: F
authors.lastname: Furfaro
authors.forename: Andrea
authors.initials: A
authors.lastname: Tortora
authors.forename: Pietro
authors.initials: P
authors.lastname: Naso
authors.forename: Cinzia
authors.initials: C
authors.lastname: D'Agate
authors.forename: Massimo
authors.initials: M
authors.lastname: Spina
authors.forename: Nunzio
authors.initials: N
authors.lastname: Belluardo
authors.forename: Aldina
authors.initials: A
authors.lastname: Bertone
authors.forename: Guido
authors.initials: G
authors.lastname: Passanisi
authors.forename: Sebastiana
authors.initials: S
authors.lastname: Malandrino
authors.forename: Luigi
authors.initials: L
authors.lastname: Familiari
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Villanacci
authors.forename: Lidia
authors.initials: L
authors.lastname: Puzzo
authors.forename: Giovanni
authors.initials: G
authors.lastname: Tuccari
authors.forename: Agata
authors.initials: A
authors.lastname: Sciacca
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Vieni
authors.forename: Stefano
authors.initials: S
authors.lastname: Costa
authors.forename: Giovanni
authors.initials: G
authors.lastname: Currò
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Magazzù
authors.forename: Concetta
authors.initials: C
authors.lastname: Sferlazzas
authors.forename: Gabrio
authors.initials: G
authors.lastname: Bassotti
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D002446:Celiac Disease / Q000175:diagnosis* / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004384:Duodenoscopy / Q000592:standards*; D004386:Duodenum / Q000473:pathology*; D005260:Female; D006801:Humans; D007223:Infant; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D015415:Biomarkers