title: Elevated calprotectin levels reveal bowel inflammation in spondyloarthritis.
abstract: Microscopic bowel inflammation is present in up to 50% of patients with spondyloarthritis (SpA) and is associated with more severe disease. Currently no reliable biomarkers exist to identify patients at risk. Calprotectin is a sensitive marker of neutrophilic inflammation, measurable in serum and stool.
  
  
  
  To assess whether serum and faecal calprotectin in addition to C-reactive protein (CRP) can be used to identify patients with SpA at risk of microscopic bowel inflammation.
  
  
  
  Serum calprotectin and CRP were measured in 125 patients with SpA. In 44 of these patients, faecal samples were available for calprotectin measurement. All 125 patients underwent an ileocolonoscopy to assess the presence of microscopic bowel inflammation.
  
  
  
  Microscopic bowel inflammation was present in 53 (42.4%) patients with SpA. Elevated serum calprotectin and CRP were independently associated with microscopic bowel inflammation. Faecal calprotectin was also significantly higher in patients with microscopic bowel inflammation. Patients with CRP and serum calprotectin elevated had a frequency of bowel inflammation of 64% vs 25% in patients with low levels of both. When either CRP or serum calprotectin was elevated, the risk was intermediate (40%) and measuring faecal calprotectin provided further differentiation. Hence we suggest a screening approach where initially serum calprotectin and CRP are assessed and, if necessary, faecal calprotectin. The model using this scenario provided an area under the ROC curve of 74.4% for detection of bowel inflammation.
  
  
  
  Calprotectin measurements in stool and serum, in addition to CRP, may provide a promising strategy to identify patients with SpA at risk of bowel inflammation and could play a role in overall patient stratification.
authors.affiliation: Department of Rheumatology, Ghent University Hospital, Ghent, Belgium Unit for Molecular Immunology and Inflammation, VIB Inflammation Research Center Ghent University, Ghent, Belgium.
authors.forename: H
authors.initials: H
authors.lastname: Cypers
authors.affiliation: Department of Rheumatology, Ghent University Hospital, Ghent, Belgium Unit for Molecular Immunology and Inflammation, VIB Inflammation Research Center Ghent University, Ghent, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: Varkas
authors.affiliation: Department of Rheumatology, Ghent University Hospital, Ghent, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Beeckman
authors.affiliation: Department of Rheumatology, Ghent University Hospital, Ghent, Belgium Unit for Molecular Immunology and Inflammation, VIB Inflammation Research Center Ghent University, Ghent, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Debusschere
authors.affiliation: Institute of Immunology, University of Münster, Münster, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Vogl
authors.affiliation: Institute of Immunology, University of Münster, Münster, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Roth
authors.affiliation: Department of Rheumatology, Ghent University Hospital, Ghent, Belgium Unit for Molecular Immunology and Inflammation, VIB Inflammation Research Center Ghent University, Ghent, Belgium.
authors.forename: M B
authors.initials: MB
authors.lastname: Drennan
authors.affiliation: Department of Pediatric Rheumatology and Immunology, University of Münster, Münster, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Lavric
authors.affiliation: Department of Pediatric Rheumatology and Immunology, University of Münster, Münster, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Foell
authors.affiliation: Department of Pathology, Ghent University, Ghent, Belgium.
authors.forename: C A
authors.initials: CA
authors.lastname: Cuvelier
authors.affiliation: Department of Gastroenterology, Ghent University Hospital, Ghent, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: De Vos
authors.affiliation: Department of Clinical Chemistry, Microbiology and Immunology, Ghent University Hospital, Ghent, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Delanghe
authors.affiliation: Department of Rheumatology, Ghent University Hospital, Ghent, Belgium.
authors.forename: F
authors.initials: F
authors.lastname: Van den Bosch
authors.affiliation: Department of Rheumatology, Ghent University Hospital, Ghent, Belgium Unit for Molecular Immunology and Inflammation, VIB Inflammation Research Center Ghent University, Ghent, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Elewaut
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis; D002097:C-Reactive Protein / Q000032:analysis; D016022:Case-Control Studies; D003092:Colitis / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D003113:Colonoscopy; D005243:Feces / Q000737:chemistry; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007422:Intestines / Q000473:pathology; D039841:Leukocyte L1 Antigen Complex / Q000032:analysis* / Q000097:blood; D008297:Male; D011446:Prospective Studies; D012372:ROC Curve; D025241:Spondylarthritis / Q000150:complications / Q000378:metabolism* / Q000473:pathology
chemical_list: D015415:Biomarkers; D039841:Leukocyte L1 Antigen Complex; D002097:C-Reactive Protein
keywords: Disease Activity; Inflammation; Spondyloarthritis