AB0189 WHAT BIOMARKERS ARE ASSOCIATED WITH LOCAL BONE LOSS AND RISK OF FRACTURES IN RHEUMATOID ARTHRITIS AT LONG-TERM FOLLOW-UP?

Abstract

BackgroundLocal and generalized bone loss in patients with rheumatoid arthritis (RA) is a manifestation of disease progression or a negative consequence. Various endogenous and exogenous factors have an effect on bone loss.ObjectivesTo study the association between the underlying osteoimmunological and immunological RA markers and local bone loss (erosion score) according to the fracture risk.MethodsThere are presented the preliminary results of a prospective long-term research to study the outcomes of local and generalized bone loss in 44 women with rheumatoid arthritis, whose age at baseline was 56.8 ± 6.9 years, the duration of follow-up 8.3 ± 1.5 years. In all patients at baseline and in dynamics serum RF, ACCP, CRP levels were measured by standard methods; serum IL-6, RANKL, CTX-I, osteocalcin and BAP (bone alkaline phosphatase) were measured by ELISA. The immunological control group was composed of healthy donors (n = 12). X-rays of hands and feet were evaluated using the Sharp-Van der Hejde method, in both groups it was observed a significant increase in the erosions score (p < 0.05). Bone mineral density(BMD) was measured at lumbar spine (L1-L4) and total hip using dual-energy X-ray absorptiometry (DXA) at baseline and in dynamics (at baseline in all patient by Hologic). The 10-year probability of fractures was measured using the fracture risk assessment tool (FRAX) in 41 (93%) patients. A high risk of fractures was estimated in 25 (61%) patients, a low risk in 16 (39%). Statistical analysis was carried out using standard parametric and non-parametric methods in Statistica. Pearson tests were used for assessing the correlation between serum levels of these molecules and erosion scores in RA.ResultsOver the follow-up period, 12 (48%) patients from high-risk group and 2 (12%) patients of low-risk group has had peripheral fractures (p = 0.01). At baseline and in dynamics in the high-risk group it was noted the higher erosion score than in the low-risk group (p = 0.001 and p = 0.002, respectively), while the delta of erosion between the groups did not significantly differ. The correlation analysis showed that in the high-risk group the erosion score and in dynamics was positively correlated (p < 0.05) with the baseline CRP level. In the low-risk group the erosion score was positively correlated (p < 0.05) with osteocalcin level (at baseline and in dynamics for both indicators), and the erosion delta was positively correlated with ACCP positivity at the second visit. In the same group, there was a significant positive correlation between the baseline erosion score and CTX-I level in dynamics. No reliable correlation between erosion score and other immunological markers levels was reported.ConclusionPreliminary analysis of long-term follow-up results showed an increase in erosion score in the high and low fracture risk groups, and fractures in the high-risk group. Higher baseline CRP values in the high- risk group were associated with a larger count of erosions both initially and in dynamics. The increase in erosion score (delta) in the low-risk group was influenced by ACCP positivity (visit in dynamics) and it was noted that the level of osteocalcin, marker reflecting osteoblast activity, was positively correlated with the erosion score, possibly reflecting remodeling/bone turnover activity.Disclosure of InterestsNone declared