The 13C-Aminopyrine Breath Test Predicts Advanced Fibrosis in Patients with Chronic Hepatitis C: A Pilot Study

Abstract

13C Aminopyrine breath test (13C-ABT) is a dynamic function test based on the use of a labelled substrate that selectively metabolized by the liver which is useful in the evaluation of hepatocyte function providing a quantitative information on liver function activity. A significant inverse correlation between C13-ABT results and liver fibrosis was found. In this study we investigate the accuracy of 13C-ABT as non-invasive method for identification of liver fibrosis compared to other non-invasive methods. Thirty-six chronic hepatitis C patients were recruited from the outpatient clinic of the Egyptian Liver Research Institute and Hospital (ELRIAH). Percutaneous liver biopsy and routine blood sampling were performed at the same day. FibroScan and 13C-ABT were done. Liver fibrosis showed strong correlation with FibroScan (r=0.717, p<0.001) and significant inverse correlation with 13C-ABT results, especially at 30 min. (r=-0.371, p=0.026). Significant correlation was found with FIB-4 (r=0.350, p=0.039) and not significant correlation was found with APRI (r=0.261, p=0.240). The cutoff value of 3.15% (dose/hr at 30 min) was associated with high prediction (positive predictive value, 60%; negative predictive value, 92.3%) yielding an overall sensitivity of 75% and specificity of 85.7%. As regards the 13C-ABT % cum. dose at 120 min, a cutoff value of 4.35 was also associated with high accuracy (PPV=47.1%, NPV=100%, Sensitivity=100% and Specificity=67.9%. These results of high accuracy is comparable to FibroScan and FIB-4, and is better than the results of APRI. 13C-aminopyrine breath test is a potential biomarker for advanced fibrosis that warrants further validation.