Geoepidemiology of Primary Biliary Cholangitis: Lessons from Switzerland

Abstract

No data on primary biliary cholangitis (PBC) are available in Switzerland. We established a national patient cohort to obtain information on PBC phenotypes and disease course in Switzerland. Local databases in all university hospitals and in two large secondary centers were searched for case finding. In addition, all primary care physicians, gastroenterologists, rheumatologists, and dermatologists were invited to contribute patients from their own medical records. PBC diagnosis was centrally reviewed. Five hundred one PBC patients were identified, 474 were included in data analysis, and 449 of them were enrolled by tertiary centers. The catchment area accounts for approximately one third of the Swiss population or approximately 2.8 million inhabitants. The median age at diagnosis was 53 years, 84% were women, and 86% were anti-mitochondrial antibody positive. The median follow-up was 5.4 years, 12.6% experienced a liver-related endpoint. Splenomegaly was present at diagnosis in one quarter of patients and in half of male patients. Approximately one third were non-responders to ursodeoxycholic acid (UDCA). The median transplant-free survival at 10 years was 85%. The following variables were independently associated with poor outcome: low platelet count at baseline (HR = 0.99, p < 0.0001), elevated alkaline phosphatase at baseline (HR = 1.36, p < 0.0001), elevated bilirubin at baseline (HR = 1.11, p = 0.001), and elevated alanine aminotransaminase (HR = 1.35, p = 0.04) after 12 months of UDCA therapy. The AUROC for the UK-PBC risk score at 5, 10, and 15 years was 0.82. The AUROC for the Globe score at 5, 10, and 15 years was 0.77. Patients included in this study are currently being enrolled in a prospective nationwide registry with biobank, taking advantage of the collaboration network generated by this study. Our study provides the first snapshot of PBC in Switzerland, describing a diagnostic delay with one quarter of patients diagnosed when already in the cirrhotic stage. We were also able to externally validate the UK-PBC risk score and the Globe score. The ongoing nationwide prospective registry will be fundamental to improve disease awareness and interdisciplinary collaborations and will serve as a platform for clinical and translational research.

Trial registration number: clinicaltrials.gov : NCT02846896; SNCTP000001870.

Keywords: Cohort study; Globe score; Primary biliary cholangitis; Prospective registry; Switzerland; UK-PBC risk score.