title: Non-invasive distinction of non-alcoholic fatty liver disease using urinary volatile organic compound analysis: early results.
abstract: OBJECTIVE
  Non-Alcoholic Fatty Liver Disease (NAFLD) is the commonest cause of chronic liver disease in the western world. Current diagnostic methods including Fibroscan have limitations, thus there is a need for more robust non-invasive screening methods. The gut microbiome is altered in several gastrointestinal and hepatic disorders resulting in altered, unique gut fermentation patterns, detectable by analysis of volatile organic compounds (VOCs) in urine, breath and faeces. We performed a proof of principle pilot study to determine if progressive fatty liver disease produced an altered urinary VOC pattern; specifically NAFLD and Non-Alcoholic Steatohepatitis (NASH).
  
  
  METHODS
  34 patients were recruited: 8 NASH cirrhotics (NASH-C); 7 non-cirrhotic NASH; 4 NAFLD and 15 controls. Urine was collected and stored frozen. For assay, the samples were defrosted and aliquoted into vials, which were heated to 40±0.1°C and the headspace analyzed by FAIMS (Field Asymmetric Ion Mobility Spectroscopy). A previously used data processing pipeline employing a Random Forrest classification algorithm and using a 10 fold cross validation method was applied.
  
  
  RESULTS
  Urinary VOC results demonstrated sensitivity of 0.58 (0.33 - 0.88), but specificity of 0.93 (0.68 - 1.00) and an Area Under Curve (AUC) 0.73 (0.55 - 0.90) to distinguish between liver disease and controls. However, NASH/NASH-C was separated from the NAFLD/controls with a sensitivity of 0.73 (0.45 - 0.92), specificity of 0.79 (0.54 - 0.94) and AUC of 0.79 (0.64 - 0.95), respectively.
  
  
  CONCLUSIONS
  This pilot study suggests that urinary VOCs detection may offer the potential for early non-invasive characterisation of liver disease using 'smell prints' to distinguish between NASH and NAFLD.
authors.affiliation: Department of Gastroenterology, University Hospital Coventry & Warwickshire, Coventry CV2 2DX; Clinical Sciences Research Institute, University of Warwick, Coventry CV2 2DX, UK. 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 CV2 2DX, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: McFarlane
authors.affiliation: School of Engineering, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Daulton
authors.affiliation: School of Engineering, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Erik
authors.initials: E
authors.lastname: Westenbrink
authors.affiliation: Department of Gastroenterology, University Hospital Coventry & Warwickshire, Coventry CV2 2DX, UK.
authors.forename: Nicola
authors.initials: N
authors.lastname: O'Connell
authors.affiliation: Department of Gastroenterology, University Hospital Coventry & Warwickshire, Coventry CV2 2DX, UK.
authors.forename: Subiatu
authors.initials: S
authors.lastname: Wurie
authors.affiliation: Department of Gastroenterology, University Hospital Coventry & Warwickshire, Coventry CV2 2DX, UK.
authors.forename: Chuka U
authors.initials: CU
authors.lastname: Nwokolo
authors.affiliation: Department of Gastroenterology, Rotherham General Hospital, Rotherham S60 2UD, UK.
authors.forename: Karna D
authors.initials: KD
authors.lastname: Bardhan
authors.affiliation: Systems Biology Centre, University of Warwick, Coventry CV4 7AL; Warwick Medical School, University of Warwick, Coventry, CV4 7AL UK.
authors.forename: Richard S
authors.initials: RS
authors.lastname: Savage
authors.affiliation: School of Engineering, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: James A
authors.initials: JA
authors.lastname: Covington
mesh_terms: D000368:Aged; D019540:Area Under Curve; D015415:Biomarkers / Q000652:urine; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D065626:Non-alcoholic Fatty Liver Disease / Q000175:diagnosis / Q000652:urine*; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D013057:Spectrum Analysis; D016482:Urinalysis; D055549:Volatile Organic Compounds / Q000652:urine*
chemical_list: D015415:Biomarkers; D055549:Volatile Organic Compounds