Correlation between systemic osteoporosis and local bone erosion with rheumatoid arthritis patients in Chinese population.

Objective: RA is a systemic auto-immune inflammatory disease that can lead to local bone erosions and generalized osteoporosis (OP). The aim of this study was to investigate the relationship between systemic osteoporosis and local bone erosion with RA patients in the Chinese population.

Methods: In total, 1235 patients with RA and 158 normal subjects were enrolled in this study. Clinical and laboratory features were recorded in detail. Information about functional class and physical activity was collected using specific questionnaires. Dual-energy X-ray absorptiometry was used to measure BMD. The MECALL castor-50-hf model X-ray scanner was used for two-hand (including wrist) photographs.

Results: The median Sharp scores differed significantly between the normal bone mass group, osteopenia group and OP group (P < 0.001). There was a modest negative linear correlation between Sharp and HAQ scores and longer disease duration (P < 0.001). There was a clear increasing trend in Sharp score, incidence of OP and HAQ score in the different DAS in 28 joints (DAS28) activity groups (P < 0.001). Spearman's correlation test showed that Sharp and HAQ scores were negatively correlated with BMD at all measured sites (femoral neck, total hip and L1-4) (P < 0.001). Logistic regression indicated that age, female gender, and Sharp and HAQ scores were independent risk factors in the occurrence of OP in RA patients. The use of DMARDs and BMI were protective factors for OP.

Conclusion: These results suggest that BMD is associated with local bone erosion among Chinese patients with RA. Local bone erosion is closely related to clinical symptoms and BMD in patients with RA.