title: A prospective evaluation of the predictive value of faecal calprotectin in quiescent Crohn's disease.
abstract: BACKGROUND
  Faecal calprotectin (FC) is a non-invasive marker of gastrointestinal inflammation.
  
  
  OBJECTIVE
  To determine whether higher FC levels in individuals with quiescent Crohn's disease are associated with clinical relapse over the ensuing 12 months.
  
  
  METHODS
  A single centre prospective study was undertaken in Crohn's disease patients in clinical remission. The receiver operating characteristic (ROC) curve for the primary endpoint of clinical relapse by 12 months, based on FC at baseline, was calculated. Kaplan-Meier curves of time to relapse were based on the resulting optimal FC cutoff for predicting relapse.
  
  
  RESULTS
  Of 97 patients recruited, 92 were either followed up for 12 months without relapsing, or reached the primary endpoint within that period. Of these, 10 (11%) relapsed by 12 months. Median FC was lower for non-relapsers, 96 μg/g (IQR 39-237), than for relapsers, 414 μg/g (IQR 259-590), (p=0.005). The area under the ROC curve to predict relapse using FC was 77.4%. An optimal cutoff FC value of 240 μg/g to predict relapse had sensitivity of 80.0% and specificity of 74.4%. Negative predictive value was 96.8% and positive predictive value was 27.6%, FC ≥240 μg/g was associated with likelihood of relapse by 12-months 12.18 (95% CI 2.55-58.2) times higher than lower values (p=0.002).
  
  
  CONCLUSIONS
  In this prospective dataset, FC is a useful tool to help identify quiescent Crohn's disease patients at a low risk of relapse over the ensuing 12 months. FC of 240 μg/g was the optimal cutoff in this cohort.
authors.affiliation: Department of Gastroenterology, Glasgow Royal Infirmary, Glasgow, United Kingdom. Electronic address: gnaismith@doctors.org.uk.
authors.forename: Graham D
authors.initials: GD
authors.lastname: Naismith
authors.affiliation: Department of Gastroenterology, Glasgow Royal Infirmary, Glasgow, United Kingdom. Electronic address: lynsmith1@nhs.net.
authors.forename: Lyn A
authors.initials: LA
authors.lastname: Smith
authors.affiliation: Robertson Centre for Biostatistics, Institute of Health and Wellbeing, University of Glasgow, Glasgow, United Kingdom. Electronic address: sarah.barry@glasgow.ac.uk.
authors.forename: Sarah J E
authors.initials: SJ
authors.lastname: Barry
authors.affiliation: Department of Gastroenterology, Glasgow Royal Infirmary, Glasgow, United Kingdom. Electronic address: Joanna.munro@ggc.scot.nhs.uk.
authors.forename: Joanna I
authors.initials: JI
authors.lastname: Munro
authors.affiliation: Department of Gastroenterology, Glasgow Royal Infirmary, Glasgow, United Kingdom. Electronic address: susan.laird@ggc.scot.nhs.uk.
authors.forename: Susan
authors.initials: S
authors.lastname: Laird
authors.affiliation: Department of Clinical Biochemistry, Glasgow Royal Infirmary, Glasgow, United Kingdom. Electronic address: karen.rankin@ggc.scot.nhs.uk.
authors.forename: Karen
authors.initials: K
authors.lastname: Rankin
authors.affiliation: Department of Gastroenterology, Glasgow Royal Infirmary, Glasgow, United Kingdom. Electronic address: john.morris@ggc.scot.nhs.uk.
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Morris
authors.affiliation: Department of Gastroenterology, Glasgow Royal Infirmary, Glasgow, United Kingdom. Electronic address: jack.winter@ggc.scot.nhs.uk.
authors.forename: Jack W
authors.initials: JW
authors.lastname: Winter
authors.affiliation: Department of Gastroenterology, Glasgow Royal Infirmary, Glasgow, United Kingdom. Electronic address: daniel.gaya@ggc.scot.nhs.uk.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Gaya
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003424:Crohn Disease / Q000175:diagnosis* / Q000378:metabolism; D005243:Feces / Q000737:chemistry; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D039841:Leukocyte L1 Antigen Complex / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D013997:Time Factors; D055815:Young Adult
chemical_list: D039841:Leukocyte L1 Antigen Complex
keywords: Crohn's disease;; Disease activity measurements;; Inflammation in IBD