S2572 Association of Vitamin D Supplementation in the Development of Osteoporosis and Osteoporosis-Related Fractures in Primary Biliary Cholangitis

Introduction: Vitamin D supplementation is recommended for osteoporosis with chronic liver disease, targeting calcium homeostasis and bone mineralization. Despite widespread use of Vitamin D supplementation, its clinical efficacy in osteoporosis progression and development of fractures has not been rigorously evaluated in PBC population. Methods: We conducted a retrospective cohort study using data from 2 U.S.-based tertiary centers from 2005–2025. Participants included postmenopausal women aged >65 years with primary biliary cholangitis (PBC) and age- and baseline serum vitamin D level-matched controls. All participants maintained consistent vitamin D supplementation (800–1000 IU/day) for ≥1 year. Fracture incidence was ascertained via comprehensive medical record review. Risk factors for fractures were evaluated using univariate and multivariate logistic regression analyses, while longitudinal fracture outcomes were modeled with mixed-effects regression modelling. Results: Among 101 PBC and 208 matched-control patients receiving vitamin D supplementation, PBC patients demonstrated lower mean T-scores (-1.98 vs -1.63; P = 0.05) and lumbar mineral density scores (0.99 vs 1.07; P = 0.01) despite comparable osteopenia and osteoporosis prevalence. Fracture prevalence was higher in PBC compared to controls (56.0% vs 36.1%), with significantly increased risk of multiple fractures (OR = 1.29, P < 0.001). Osteoporosis medication reduced fracture risk (OR = 0.80, P = 0.05). Mixed-effects models revealed diverging 10-year trajectories with only marginal risk reduction in PBC patients from 75% to 62% while substantial risk reduction from 59% to 24% in controls. Conclusion: Standard vitamin D supplementation may not adequately protect PBC patients from fractures, as evidenced by persistently elevated rates and marginal long-term risk reduction. However, in combination with osteoporosis medications, Vitamin D supplementation partially reduced risk of osteoporosis-related fractures. Further studies are needed to identify risk factors of metabolic bone disease progression and fracture development in PBC to individualize prevention and treatment approach in this population.