Misclassification of UDCA treatment response in patients with primary biliary cholangitis (PBC) in the real-world setting

Introduction and Objectives: Treatment response to ursodeoxycholic acid (UDCA) in primary biliary cholangitis (PBC) is assessed after 12 months by Paris II criteria. In the German PBC registry, individuals were stratified into adequate and inadequate Paris II responders. We analyzed the concordance between clinical judgement and formal Paris II classification. Patients and Methods: Physician-assessed UDCA treatment response was compared to formal Paris II criteria (alkaline phosphatase (ALP) or aspartate-aminotransferase (AST) >1.5 x ULN or bilirubin >1 mg/dL).

Results

10/130 (8%) cases were misclassified as inadequate UDCA responders, 44/253 (17%) as adequate responders despite not meeting Paris II criteria. Incorrectly classified responders occurred in 26% versus 13% of individuals at secondary and tertiary centers (p = 0.0141). At secondary centers, 86% of misclassified responders had ALP >1.5 × ULN and 5% had bilirubin >1 mg/dL, compared with 32% and 27% at tertiary centers. ALP levels >1.5 x ULN occurred significantly more often at secondary centers (p = 0.0005). At secondary centers, ALP levels at diagnosis were higher in misclassified versus correctly classified responders (3.6 ± 3.0 x ULN vs. 1.7 ± 0.9 x ULN, p < 0.001) and remained higher after 12 months of therapy (2.3 ± 1.2 vs. 0.9 ± 0.3 × ULN, p < 0.001).