The Influence of Anti-Citrullinated Polypeptide Antibodies on Bone Mineral Density Decrease and Incident Major Osteoporotic Fractures in Patients with Rheumatoid Arthritis: A Retrospective Case-Control Study

Abstract

Background: Effects of anti-citrullinated polypeptide antibodies (ACPA) on the bone mineral density (BMD) reduction and incidence of major osteoporotic fractures (MOF) in patients with rheumatoid arthritis (RA) were evaluated using a retrospective longitudinal case-control study. Methods: Patients with RA who were examined using dual-energy X-ray absorptiometry and simultaneously treated for more than 5 years were recruited. BMD absolute value and Z-scores at initial measurements (baseline) and changes of these values from baseline were assessed, and associations between BMD and candidate risk factors including ACPA positivity and serum titer levels were statistically evaluated. Additional statistical evaluations of ACPA positivity in regard to the incidence of MOF were tested. Results: A total of 222 patients were included. Higher ACPA titers correlated significantly with lower BMD and Z-scores at baseline using a multivariate model (p < 0.05). ACPA positivity correlated significantly with lower values and an annual decrease in the Z-score in total hip at follow-up using a univariate model (p < 0.05), whereas no significant correlation was found using a multivariate model. Z-scores in the ACPA-positive group were significantly lower than those of the ACPA-negative group (p < 0.05). However, ACPA-positivity demonstrated no higher risk for incident MOF. Conclusions: The presence of ACPA is a potential risk of BMD loss however weak.