Background: The (13)C-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 (13)C-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 [DOB(max)(%)].
Results: A high linear association between both methods was observed (R(2) = 0.95, P < 0.001). For all DOB and DOB(max), 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.