Role of (13)C methacetin breath test for non invasive staging of liver fibrosis in patients with chronic hepatitis C

BACKGROUND & OBJECTIVES: The development and evaluation of non invasive tests to assess liver fibrosis have been an active field of research. The present study was carried out to evaluate the role of (13)C-methacetin breath test (13)C- MBT) as a non invasive tool for liver fibrosis staging in patients with chronic hepatitis C (CHC). METHODS: (13)C-Methacetin breath test was performed in 115 patients with CHC histologically proven and in 55 healthy controls. All patients and controls underwent routine liver function tests. The CHC patients underwent histological assesment of liver by percutaneous liver biopsy. The correlation between the (13)C-methacetin breath test and liver biopsy was tested using Kendall's rank correlation coefficients. The overall validity was expressed as area under receiver operating characteristic curve (AUROC) with 95%CI. RESULTS: Delta over baseline values (DOB) of CHC patients at 20 min were significantly reduced compared with control (16. 2 vs. 21. 06%, P<0.001). There were also significant differences between CHC patients and controls as regard the metabolization speed (dose /h at 20 min (17.80 vs 28.6, P<0.001) and metabolization capacity (cumulative recovery after 60 min (13.8 vs 20.4 P<0.001). The best (13)C-MBT parameter correlated with fibrosis was DOB at 20 min (r= - 0.596). The optimal cut-off for the diagnosis of advanced fibrosis (F≥3) was 15.2 per cent, with AUROC= 0.902, 95%CI: (0.851-0.938), a sensitivity of 82 per cent and a specificity of 80 per cent. DOB at 20 min predicted even better cirrhosis: AUROC = 0.932 95 per cent CI = 0.901-0.953, a sensitivity of 96 per cent and a specificity of 92 per cent. INTERPRETATION & CONCLUSIONS: Based on our findings the (13)C – methacetin breath test appears to be a promising tool to identify CHC patients with advanced fibrosis and to replace liver biopsy. Further studies need to be done to assess its potential to be used in regular clinical practice.