title: Comparison of six different calprotectin assays for the assessment of inflammatory bowel disease.
abstract: OBJECTIVE
  Faecal calprotectin is a valuable noninvasive marker for inflammatory bowel disease (IBD). The aim of our study was to determine the correlation between six different calprotectin assays and compare their performance for diagnosis and follow up of IBD.
  
  
  METHODS
  Thirty-one patients with suspected IBD and 31 patients in follow up were included. We determined calprotectin by means of three rapid immmunochromatographic tests, two enzyme-linked immunosorbent assays, and one automated fluoroimmunoassay. Results were correlated with endoscopic and histological findings.
  
  
  RESULTS
  Although all methods correlated significantly, slopes and intercepts differed extensively, with up to 5-fold quantitative differences between assays. Sensitivity and specificity for diagnosis of IBD were 82-83 and 84-89%, respectively. For follow up, sensitivity in detecting mild ulcerative colitis was 71-100%. In moderate-to-severe ulcerative colitis, sensitivity was 100% for all assays. Specificity was 67-86% in both subgroups. In Crohn's disease, only moderate-to-severe disease could be differentiated from remission, with sensitivity 83-86% and specificity 75% for all tests.
  
  
  CONCLUSIONS
  All calprotectin assays showed comparable clinical performance for diagnosis of IBD. For follow up, performance was acceptable, except for mild Crohn's disease. Because of the large quantitative differences, further efforts are needed to standardize calprotectin assays.
authors.affiliation: Department of Laboratory Medicine, Imelda General Hospital, Bonheiden, Belgium.
authors.forename: Delphine
authors.initials: D
authors.lastname: Labaere
authors.affiliation: Department of Laboratory Medicine, Imelda General Hospital, Bonheiden, Belgium.
authors.forename: Annick
authors.initials: A
authors.lastname: Smismans
authors.affiliation: Department of Gastroenterology, Imelda General Hospital, Bonheiden, Belgium.
authors.forename: August
authors.initials: A
authors.lastname: Van Olmen
authors.affiliation: Department of Gastroenterology, Imelda General Hospital, Bonheiden, Belgium.
authors.forename: Paul
authors.initials: P
authors.lastname: Christiaens
authors.affiliation: Department of Gastroenterology, Imelda General Hospital, Bonheiden, Belgium ; Department of Gastroenterology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Geert
authors.initials: G
authors.lastname: D'Haens
authors.affiliation: Department of Gastroenterology, Imelda General Hospital, Bonheiden, Belgium.
authors.forename: Veerle
authors.initials: V
authors.lastname: Moons
authors.affiliation: Department of Gastroenterology, Imelda General Hospital, Bonheiden, Belgium.
authors.forename: Pieter-Jan
authors.initials: PJ
authors.lastname: Cuyle
authors.affiliation: Department of Laboratory Medicine, Imelda General Hospital, Bonheiden, Belgium.
authors.forename: Johan
authors.initials: J
authors.lastname: Frans
authors.affiliation: Department of Gastroenterology, Imelda General Hospital, Bonheiden, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Bossuyt
keywords: Calprotectin; Crohn’s disease; diagnosis; follow up; inflammatory bowel disease; ulcerative colitis