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.

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.