Bagus P. P. Suryana, Robert K. Will, Annie Lim, Bill Breidahl
Objective: To evaluate the bone density and bone metabolism in women with rheumatoid arthritis (RA), focusing on disease activity, joint erosion, and RA-epitope. Methods: Disease activity was assessed using erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, Ritchie articular index (RAI), and disease activity score (DAS). The presence of joint erosion was assessed using wrist-hand and feet X-ray, and wrist-hand magnetc resonance imaging. A fasting metabolic bone study was done including serum calcium, phosphate, 25(OH) vitamin D, parathyroid hormone (PTH), alkaline phosphatase (ALP), osteocalcin, and urine deoxypyridinoline/creatinine (DPD/Cr) ratio. Bone mineral density (BMD) was measured at hip, spine, distal forearm, hand, and total body using dual energy X-ray absorptiometry (DEXA) machine. HLA-DRBl genes were examined using DNA sequencing based typing. Results: Seventy-six women with RA according to 1987 American College of Rheumatology (ACR) criteria with clinical onset equal to or less than 5 years were examined. Mean (SD) of age was 55.4 (13.7) years, disease duration 34.9 (36.4) months, and 96% with ACR functional criteria class I and II. HLA typing demonstrated that 61.4% of them have the RA shared-epitope (QRRAA or QKRAA or RRRAA) in their HLA-DRBl alleles. Most of them had been receiving disease-modifying antirheumatic drugs and glucocorticoid. Erosive disease was significantly correlated with intertrochanter BMD (P = 0.044), serum calcium (P = 0.005), and urine DPD/Cr ratio (P < 0.001), Patients with erosive disease had higher DAS (P = 0.017), lower serum calcium (P = 0.006), and higher urine DPD/Cr ratio (P < 0.001). There were no statistically significant differences in serum ALP, osteocalcin, 25(OH) vitamin D, and PTH. Patients with erosive disease had lower BMD at all sites including hip, forearm, hand, lumbar spine, and total body, though only statistically significant at intertrochanter (P = 0.042). Bivariate correlation demonstrated that at all sites BMD, except femoral neck and hand BMD, negatively correlated with urine DPD/Cr ratio. Logistic regression model showed that erosive disease was a significant factor for low bone density (T-score <-l) at intertrochanter (OR= 6.0; 95% CI = 1.3-27.3; P = 0.020), total hip (OR = 5.5; 95% CI = 1.1-26.8; P = 0.035), and distal radius-ulna (OR = 3.9; 95% CI = 1.1-14.0; P = 0.041), Conclusion: Patients with erosive disease demonstrated lower BMD, lower serum calcium level, and higher bone resorption. Erosive disease was a significant factor for osteopenia or osteoporosis. ©Asia Pacific League of Associations for Rheumatology.
Department of Internal Medicine, Dr. Saiful Anwar Hospital, Brawijaya University, Malang, Indonesia; Department of Rheumatology, Royal Perth Hospital, Australia; Department of Radiology, Royal Perth Hospital, Australia
