Applicability and prognostic value of histologic scoring systems in primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease. At present, there is no appropriate histologic scoring system available for PSC, evaluating both degree of necroinflammatory activity (grade) and fibrosis (stage). The aim of this study was to assess if three scoring systems, commonly used in different liver diseases could be applied for grading and/or staging of PSC.

Sixty-four PSC patients from a Dutch cohort, who underwent diagnostic liver biopsy, were included. Staging was scored using Ishak, Nakanuma, and Ludwig systems. Grading was scored using Ishak and Nakanuma systems. Three measures of outcome were defined; transplant-free survival, time to liver transplantation (LTx) and occurrence of cirrhosis related symptoms (CRS). Association of grade and stage with outcome was estimated using Kaplan-Meier log-rank test, and Cox regression analysis. Correlation with biochemistry was assessed by Spearman's rank test.

There were strong associations between disease stage measured by Ishak, Nakanuma, and Ludwig staging systems with both outcome measuring transplant-free survival (Hazard ratio (HR) 2.56; 95% CI 1.11-5.89, HR 6.53; 95% CI 2.01-21.22, HR 1.94; 95% CI 1.00-3.79, respectively), and time to LTx (HR 4.18; 95%CI 1.51-11.56, HR 7.05; 95% CI 1.77-28.11, HR 3.13; 95%CI 1.42-6.87, respectively). Ishak and Nakanuma grading systems were not associated with CRS. Weak correlations between histopathology and liver biochemistry were shown.

Applying the Nakanuma, Ishak, and Ludwig histopathological staging systems is feasible and clinically relevant given their association with transplant-free survival and time to LTx. This suggests that these staging systems could be likely candidates for surrogate endpoints and stratification purposes in clinical trials in PSC.