Extrahepatic Autoimmune Disease in People With Primary Biliary Cholangitis: Nationwide Occurrence and Relation to...

Primary biliary cholangitis (PBC) is associated with several extrahepatic autoimmune diseases (EHAIDs), but reliable prevalence estimates are scarce. We determined the occurrence of EHAIDs in a nationwide population with PBC and their association with outcome.

The retrospective Dutch PBC Cohort Study (DPCS) includes every identifiable person with PBC in the Netherlands from 1990 up to 2023. Survival analyses were used to assess whether EHAID is associated with liver transplant (LT)-free survival or liver disease progression.

In total, 4,351 individuals were included of whom 1,186 (27.3%) were diagnosed with EHAIDs. Hypothyroidism was the most common EHAID (35.6%), followed by Sjögren's syndrome (18.3%). EHAIDs were present at baseline in 957 (80.7%) of cases. At baseline, people with EHAIDs were more frequently female (92.1% vs 87.0%, p<0.001), had cirrhosis less frequently (5.4% vs 7.3%, p=0.046) and had lower GGT levels (5.79 xULN vs 6.55 xULN, p<0.001). The 10-year LT-free survival was 83.3% (95% CI 81.8-84.9) among those with EHAID at baseline vs 84.6% (95% CI 81.8-87.6) among those without (p=0.378). The absent association between EHAID and outcome remained in multivariable analyses (aHR 0.81, 95% CI 0.63-1.05, p=0.121 for LT-free survival and aHR 0.92, 95% CI 0.65-1.32, p=0.662 for liver disease progression).

In a nationwide population of individuals with PBC, EHAIDs are common. EHAIDs were mostly present at baseline and were not associated with long-term clinical outcome. As symptoms in people with PBC may be aggregated or caused by concurrent EHAIDs, this study is important to improve the awareness and evaluation of EHAIDs in PBC.