13C-Aminopyrine breath test to evaluate severity of disease in patients with chronic hepatitis C virus infection

Background: There are few data on the use of the C-13-aminopyrine breath test to evaluate the severity of disease in patients with hepatitis C virus-related chronic liver disease, although these patients represent one of the most important problems in clinical hepatology. Aims: To compare C-13-aminopyrine breath test results of patients with hepatitis C virus-related chronic hepatitis and Child-Pugh class A cirrhosis with those of normal subjects, and to evaluate different methods of expressing C-13-aminopyrine breath test results. Methods: Twenty-four patients with hepatitis C virus-related chronic hepatitis and 17 patients with Child-Pugh class A cirrhosis underwent C-13-aminopyrine breath test. Breath samples were collected every 30 min up to 2 h after C-13-aminopyrine administration. C-13-Aminopyrine breath test results were expressed as a percentage of the administered dose of C-13 recovered per hour (% dose/h) and the cumulative percentage of administered dose of C-13 recovered Over time (% dose cum). Nineteen healthy subjects served as controls. Patients with hepatitis C virus-related chronic hepatitis were divided into subgroups on the basis of histological staging and grading. Results: The C-13-aminopyrine breath test result (% dose/h) at 30 min was significantly different among the three subgroups of subjects (normal subjects, 11.5+/-3.5: chronic hepatitis patients. 8.1+/-4.1; cirrhosis patients, 5.0+/-3.1: P<0.0005). Moreover, the differences between chronic hepatitis and cirrhosis patients were statistically significant (P<0.03). The fibrosis score showed a significant inverse correlation with the C-13-aminopyrine breath test result (% dose/h) at 30 min (r(s) = -0.409, P=0.05). The C-13-aminopyrine breath test result (% dose/h) at 30 min also allowed normal subjects and chronic hepatitis patients with low (less than or equal to2) or high (> 2) fibrosis scores to be distinguished. The C-13-aminopyrine breath test results (% dose cum) at 30, 60 and 90 min allowed discrimination between normal subjects and chronic hepatitis and cirrhosis patients. The C-13-aminopyrine breath test result (% dose cum) was also able to distinguish between normal subjects and chronic hepatitis patients with high but not low fibrosis scores. Both C-13-aminopyrine breath test results (% dose/h and % dose cum) at 120 min allowed the differentiation between normal subjects and chronic hepatitis patients with high (greater than or equal to6) necro-inflammatory activity. Conclusions: In patients with hepatitis C virus-related chronic liver disease, the C-13-aminopyrine breath test proved to be safe and easy to perform. and was able to evaluate different degrees of liver function impairment which were partly correlated to clinical and histological evaluation. In future studies, C-13-aminopyrine breath test results should be expressed in a standardized fashion to permit comparison.