The relationship between transient elastography and histological collagen proportionate area for assessing fibrosis in chronic viral hepatitis

BACKGROUND: Collagen proportionate area (CPA) has a better correlation with hepatic venous pressure gradient (HVPG) than with Ishak stage. Liver stiffness measurement (LSM) is proposed as non invasive marker of portal hypertension/disease progression. Our aim was to compare LSM and CPA with Ishak staging in chronic viral hepatitis, and HVPG in HCV hepatitis after transplantation. METHODS: One hundred and sixty-nine consecutive patients with chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infections pre/post liver transplantation (LT), had a liver biopsy combined with LSM (transient elastography), CPA (biopsies stained with Sirius Red and evaluated by digital image analysis and expressed as CPA) and HVPG (measured contemporaneously with transjugular biopsies in LT HCV patients). RESULTS: LSM was dependent on CPA in HBV (r (2) = 0.61, p < 0.0001), HCV (r (2) = 0.59, p < 0.0001) and LT groups (r (2) = 0.64, p < 0.0001). In all three groups, CPA and Ishak were predictors of LSM, but multivariately CPA was better related to LSM (HBV: r (2) = 0.61, p < 0.0001; HCV: r (2) = 0.59, p < 0.0001; post-LT: r (2) = 0.68, p < 0.0001) than Ishak stage. In the LT group, multiple regression analysis including HVPG, LSM, aspartate aminotransferase to platelet ratio index (APRI) and Ishak stage/grade, showed that only CPA was related to HVPG (r (2) = 0.41, p = 0.01), both for HVPG ≥6 mmHg (OR 1.34, 95 % CI 1.14-1.58; p < 0.0001) or ≥10 mmHg (OR 1.25, 95 % CI 1.06-1.47; p = 0.007). CONCLUSION: CPA was related to LSM in HBV or HCV hepatitis pre/post-LT. CPA was better related to LSM than Ishak stage. In the LT HCV group, CPA was better related to HVPG than Ishak stage/grade, LSM or APRI. CPA may represent a better comparative histological index for LSM, rather than histological stages.