13C-methacetin breath test as a quantitative liver function test in patients with chronic hepatitis C infection: Continuous automatic molecular correlation spectroscopy compared to isotopic ratio mass spectrometry

Abstract

Background: The 13C-methacetin breath test (MBT) has been proposed for the non-invasive evaluation of hepatic microsomal activity. Aim: To test a new continuous breath analysis system (BreathID) in comparison with gold-standard isotopic ratio mass spectrometry (IRMS) in patients with chronic hepatitis C infection and to assess the diagnostic performance of these validation data compared with liver biopsy for the quantification of liver fibrosis. Methods: Fifty patients at different METAVIR stages received 75 mg of 13C-methacetin. Breath isotopic ratio was analysed over 90 min by BreathID (one sample/3 min; BreathID) and IRMS (one sample/10 min). Results were expressed as delta over baseline [DOB (%)] at each time interval and maximal DOB [DOBmax(%)]. Results: A high linear association between both methods was observed (R2 = 0.95, P < 0.001). For all DOB and DOBmax, the limits of agreement by Bland-Altman analysis were within the predefined maximal width of s.d. <2.5%. MBT parameters in patients with high-grade fibrosis were different from patients with low-grade fibrosis (P < 0.001). Conclusion: The MBT obtained by an easy to operate, automated BreathID provides results comparable with standard IRMS and differentiates fibrosis grades in patients with chronic hepatitis C infection. © 2007 The Authors.