Laboratory risk factors for coexistent primary biliary cholangitis in patients with Sjögren's syndrome: a retrospective study.

Background: Limited research exists on the laboratory characteristics of coexistent primary biliary cholangitis (PBC) and Sjögren's syndrome (SS). This study aimed to investigate the laboratory risk factors for the coexistence of PBC in patients with SS.

Methods: Eighty-two patients with coexistent SS and PBC (median age 52.50 years) and 82 age- and sex-matched SS controls were retrospectively enrolled between July 2015 and July 2021. The clinical and laboratory characteristics of the two groups were compared. Laboratory risk factors for the coexistence of PBC in patients with SS were analyzed using logistic regression analysis.

Results: Both groups had a similar prevalence of hypertension, diabetes, thyroid disease, and interstitial lung disease. Compared with the SS group, patients in the SS + PBC group had higher levels of liver enzymes, immunoglobulins M (IgM), G2, and G3 (P < 0.05). The percentage of patients with an antinuclear antibody (ANA) titre > 1:10000 in the SS + PBC group was 56.1%, higher than that in the SS group (19.5%, P < 0.05). Additionally, cytoplasmic, centromeric, and nuclear membranous patterns of ANA and positive anti-centromere antibody (ACA) were observed more frequently in the SS + PBC group (P < 0.05). Logistic regression analysis showed that elevated IgM levels, high ANA titre, cytoplasmic pattern, and ACA were independent risk factors for PBC coexistence in SS.

Conclusions: In addition to established risk factors, elevated IgM levels, positive ACA, and high ANA titre with cytoplasmic pattern provide clues to clinicians for the early screening and diagnosis of PBC in patients with SS.