The goal of this registry is to better understand how primary biliary cholangitis develops over time, including the role of disease-related biomarkers, complications of the disease, and symptom burden. Patients with primary biliary cholangitis treated at participating centres in Austria will be invited to take part in this prospective registry. Participation in an associated biobank is optional. Clinical and laboratory data will be collected, and patients will be followed regularly through scheduled clinic visits. In addition, biological samples (serum, plasma, and, if available, liver tissue) may be collected and stored in the biobank for future research.

This is a prospective, multicenter registry of patients with primary biliary cholangitis (PBC). Patients presenting to hepatology outpatient clinics at participating centers in Austria will be offered inclusion in the registry. For patients who are already under care at the respective center at the time of enrollment, retrospective data will be collected and subsequently complemented with prospective follow-up data. Registry participants will be managed according to current treatment guidelines and standard clinical practice at the discretion of the individual investigators. Demographic, clinical, and laboratory parameters will be recorded at the time of registry inclusion and subsequently at follow-up visits. The frequency of clinical visits will be determined by clinical necessity and will generally occur every 3-6 months, although shorter intervals may be required. No study-specific interventions will be performed. If diagnostic material is obtained as part of routine clinical care (e.g., blood sampling or liver biopsy), patients will be asked to provide informed consent for the storage of additional material (blood) or residual material (liver biopsy specimens) in a biobank for research purposes. Next to the detailed characterization of patients by epidemiologic, clinical and laboratory parameters, the presence of overlapping liver disease etiologies and the severity of liver disease will be assessed. Specifically, this includes the assessment of liver-related complications including events of hepatic decompensation, measurements of liver and spleen stiffness, as well as an assessment of portal hypertension severity based on imaging findings and hepatic venous pressure gradient measurement in selected patients. Furthermore, assessments include a detailed evaluation of current and prior disease-specific treatments and extrahepatic symptom burden. Data will be entered into a pseudonymized database by study personnel. Data transfer from participating centers to the Medical University of Vienna will be conducted either via encrypted electronic transfer or by direct transfer using encrypted hardware (e.g., hard drives or USB devices). Patient identifiers (e.g., name) will not be entered into the database. All other patient data will be recorded as datasets in a pseudonymized data table. All participating patients will be assigned a consecutive study number, thereby ensuring pseudonymization for subsequent analyses. This pseudonymization through assignment of a unique study number will also apply to samples stored in the associated biobank. Access to the data will be restricted to authorized personnel. A stated objective of the registry is the systematic inclusion of patients with PBC-associated liver disease who are managed at the specialized outpatient clinic of Vienna General Hospital or at specialized outpatient clinics of participating centers. This is particularly relevant from an epidemiological perspective to determine and capture the number of patients across different clinical stages of the disease. Therefore, the aim is to include all patients with PBC who are willing to participate from these specialized outpatient clinics, and no formal sample size calculation has been performed. Participants included in this registry are unlikely to derive any direct benefit from participation. As participation in the registry and the associated biobank does not involve any invasive procedures, no relevant risks are expected. Patients may withdraw their participation in the registry and/or the biobank at any time.

Inclusion Criteria:

• Age >18 years
• Confirmed diagnosis of primary biliary cholangitis (at least two of the following three criteria must be fulfilled: persistent elevation of alkaline phosphatase above the upper limit of normal for at least 6 months; presence of antimitochondrial antibodies or PBC-specific antinuclear antibodies; characteristic histopathology)
• Written informed consent for participation in the registry

Exclusion Criteria:

• Withdrawal of written informed consent

Patient with primary biliary cholangitis diagnosed and/or treated at one of the participating centers in Austria will be screened for inclusion/exclusion criteria.

Data will be entered into a pseudonymized database by study personnel. Data transfer from participating centers to the Medical University of Vienna will be conducted either via encrypted electronic transfer or by direct transfer using encrypted hardware (e.g., hard drives or USB devices).