title: Comparison of two immunoassays for measurement of faecal calprotectin in detection of inflammatory bowel disease: (pre)-analytical and diagnostic performance characteristics.
abstract: BACKGROUND
  Symptoms of inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) can overlap. Faecal calprotectin has recently been established to be a non-invasive marker for neutrophilic intestinal inflammation. We compared two devices for extraction of faecal calprotectin. Based on these results, two immunoassays for measurement of faecal calprotectin were evaluated.
  
  
  METHODS
  Samples were extracted using the Thermo Fisher extraction device (Thermo Fisher Scientific) and Smart Pep extraction device (Roche Diagnostics) and measured with the EliA Calprotectin immunoassay (Thermo Fisher Scientific) on ImmunoCAP 250. The performance of both assays was investigated by enrolling 183 consecutive patients (79 males, 104 females; median age 32 years) with clinical suspicion of IBD. Faecal calprotectin was measured using a recently launched immunoassay, EliA Calprotectin in comparison with an established immunochomatographic point-of-care-test (POCT, Quantum Blue Calprotectin; Bühlmann). Results were compared with endoscopic and histological findings.
  
  
  RESULTS
  The use of the Thermo Fisher extraction device resulted in an underestimation of faecal calprotectin concentrations, especially in liquid stool samples. IBD was diagnosed in 51/183 patients (27.9%) [Crohn's disease (CD, n=37), ulcerative colitis (UC, n=14)]. After adjusting the optimal cut-off for detection of IBD using receiver operating curve analysis, a sensitivity of 94.1% and 90.2% and specificity of 87.9% and 90.9% for the EliA and POCT assay, respectively, were obtained.
  
  
  CONCLUSIONS
  The Thermo Fisher device is not reliable for extraction of faecal calprotectin. The performance characteristics of the EliA Calprotectin assay are statistically equivalent to the Bühlmann POCT.
authors.forename: Matthijs
authors.initials: M
authors.lastname: Oyaert
authors.forename: Charlotte
authors.initials: C
authors.lastname: Trouvé
authors.forename: Filip
authors.initials: F
authors.lastname: Baert
authors.forename: Dieter
authors.initials: D
authors.lastname: De Smet
authors.forename: Michel
authors.initials: M
authors.lastname: Langlois
authors.forename: Hilde
authors.initials: H
authors.lastname: Vanpoucke
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003093:Colitis, Ulcerative / Q000175:diagnosis; D003424:Crohn Disease / Q000175:diagnosis; D003937:Diagnosis, Differential; D005243:Feces / Q000737:chemistry*; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D015212:Inflammatory Bowel Diseases / Q000175:diagnosis*; D043183:Irritable Bowel Syndrome / Q000175:diagnosis; D039841:Leukocyte L1 Antigen Complex / Q000032:analysis* / Q000302:isolation & purification; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D039841:Leukocyte L1 Antigen Complex