title: Non-invasive estimation of liver fibrosis in non-alcoholic fatty liver disease using the 13 C-caffeine breath test.
abstract: OBJECTIVE
  Fibrotic progression in non-alcoholic fatty liver disease (NAFLD) is associated with impaired hepatic function. The (13) C-caffeine breath test (CBT) is a non-invasive, quantitative test of liver function. We sought to determine the utility of the CBT in detecting hepatic fibrosis in NAFLD.
  
  
  METHODS
  The CBT was applied to 48 patients with NAFLD. CBT results were compared to clinical, biochemical and histological data. Twenty-four healthy subjects served as controls.
  
  
  RESULTS
  Patients with simple steatosis had similar CBT values (2.28 ± 0.71 Δ‰ per 100 mg caffeine) to controls (2.31 ± 0.85, P = 1.0). However, CBT was significantly reduced in patients with non-alcoholic steatohepatitis (1.59 ± 0.65, P = 0.005) and cirrhosis (1.00 ± 0.73, P < 0.001). CBT significantly correlated with Brunt's fibrosis score (r = -0.49, P < 0.001) but not with steatosis (P = 0.23) or inflammation (P = 0.08). CBT also correlated with international normalized ratio (r = -0.61, P < 0.001), albumin (r = 0.37, P = 0.009), aspartate aminotransferase/alanine aminotransferase (r = -0.34, P = 0.018) and platelets (r = 0.31, P = 0.03). On multivariate analysis, age (odds ratio 1.12, 95% confidence interval 1.042-1.203, P = 0.002) and CBT (OR 0.264, 95% CI 0.084-0.822, P = 0.02) were independent predictors of significant fibrosis (F ≥ 2). CBT yielded an area under the receiver operating characteristic curve of 0.86 for the diagnosis of cirrhosis.
  
  
  CONCLUSIONS
  The CBT reflects the extent of hepatic fibrosis in NAFLD and represents a non-invasive predictor of fibrosis severity in this condition.
authors.affiliation: Department of Gastroenterology and Hepatology, Concord Hospital, University of Sydney, Sydney, Australia. gpark@med.usyd.edu.au
authors.forename: Gordon J-H
authors.initials: GJ
authors.lastname: Park
authors.forename: Elke
authors.initials: E
authors.lastname: Wiseman
authors.forename: Jacob
authors.initials: J
authors.lastname: George
authors.forename: Peter H
authors.initials: PH
authors.lastname: Katelaris
authors.forename: Francis
authors.initials: F
authors.lastname: Seow
authors.forename: Caroline
authors.initials: C
authors.lastname: Fung
authors.forename: Meng C
authors.initials: MC
authors.lastname: Ngu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001706:Biopsy; D001944:Breath Tests; D002110:Caffeine; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005234:Fatty Liver / Q000150:complications*; D005260:Female; D006801:Humans; D008103:Liver Cirrhosis / Q000175:diagnosis* / Q000209:etiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009517:New South Wales; D065626:Non-alcoholic Fatty Liver Disease; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012372:ROC Curve; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D055815:Young Adult
chemical_list: D002110:Caffeine