title: Non-invasive exhaled volatile organic biomarker analysis to detect inflammatory bowel disease (IBD).
abstract: BACKGROUND
  Early inflammatory bowel disease (IBD) diagnosis remains a clinical challenge. Volatile organic compounds (VOCs) have shown distinct patterns in Crohn's disease (CD) and ulcerative colitis (UC). VOC production, reflecting gut fermentome metabolites, is perturbed in IBD. VOC sampling is non-invasive, with various compounds identified from faecal, breath and urine samples. This study aimed to determine if FAIMS (field asymmetric ion mobility spectroscopy) analysis of exhaled VOCs could distinguish IBD from controls.
  
  
  METHODS
  Seventy-six subjects were recruited, 54 established IBD (25 CD, 29 UC) and 22 healthy controls. End expiratory breath was captured using a Warwick device and analysed by FAIMS. Data were pre-processed using wavelet transformation, and classification performed in a 10-fold cross-validation. Feature selection was performed using Wilcoxon rank sum test, and sparse logistic regression gave class predictions, to calculate sensitivity and specificity.
  
  
  RESULTS
  FAIMS breath VOC analysis showed clear separation of IBD from controls, sensitivity: 0.74 (0.65-0.82), specificity: 0.75 (0.53-0.90), AUROC: 0.82 (0.74-0.89), p-value 6.2×10(-7). IBD subgroup analysis distinguished UC from CD: sensitivity of 0.67 (0.54-0.79), specificity: 0.67 (0.54-0.79), AUROC: 0.70 (0.60-0.80), p-value 9.23×10(-4).
  
  
  CONCLUSIONS
  This confirms the utility of exhaled VOC analysis to distinguish IBD from healthy controls, and UC from CD. It conforms to other studies using different technology, whilst affirming exhaled VOCs as biomarkers for diagnosing IBD.
authors.affiliation: Department of Gastroenterology, University Hospital Coventry & Warwickshire, Coventry, United Kingdom; Clinical Sciences Research Institute, University of Warwick, Coventry, United Kingdom. Electronic address: r.arasaradnam@warwick.ac.uk.
authors.forename: Ramesh P
authors.initials: RP
authors.lastname: Arasaradnam
authors.affiliation: Department of Gastroenterology, University Hospital Coventry & Warwickshire, Coventry, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: McFarlane
authors.affiliation: School of Engineering, University of Warwick, Coventry, United Kingdom.
authors.forename: Emma
authors.initials: E
authors.lastname: Daulton
authors.affiliation: Centre for Complexity Science, University of Warwick, United Kingdom.
authors.forename: Jim
authors.initials: J
authors.lastname: Skinner
authors.affiliation: Department of Gastroenterology, University Hospital Coventry & Warwickshire, Coventry, United Kingdom.
authors.forename: Nicola
authors.initials: N
authors.lastname: O'Connell
authors.affiliation: Department of Gastroenterology, University Hospital Coventry & Warwickshire, Coventry, United Kingdom.
authors.forename: Subiatu
authors.initials: S
authors.lastname: Wurie
authors.affiliation: Department of Gastroenterology, University Hospital Coventry & Warwickshire, Coventry, United Kingdom.
authors.forename: Samantha
authors.initials: S
authors.lastname: Chambers
authors.affiliation: Department of Gastroenterology, University Hospital Coventry & Warwickshire, Coventry, United Kingdom.
authors.forename: Chuka
authors.initials: C
authors.lastname: Nwokolo
authors.affiliation: Department of Gastroenterology, Rotherham General Hospital, Rotherham, United Kingdom.
authors.forename: Karna
authors.initials: K
authors.lastname: Bardhan
authors.affiliation: Centre for Complexity Science, University of Warwick, United Kingdom; Warwick Medical School, University of Warwick, Coventry, United Kingdom.
authors.forename: Richard
authors.initials: R
authors.lastname: Savage
authors.affiliation: School of Engineering, University of Warwick, Coventry, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Covington
mesh_terms: D000328:Adult; D015415:Biomarkers; D001944:Breath Tests; D016022:Case-Control Studies; D003093:Colitis, Ulcerative / Q000175:diagnosis*; D003424:Crohn Disease / Q000175:diagnosis*; D005260:Female; D005285:Fermentation; D000069196:Gastrointestinal Microbiome; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis; D055549:Volatile Organic Compounds / Q000032:analysis*
chemical_list: D015415:Biomarkers; D055549:Volatile Organic Compounds
keywords: Breath; Crohn's; IBD; IMS; Non-invasive; UC; Volatile organic compounds