Objective: To determine the reproducibility, accuracy, and linearity of hand bone mineral content (BMC) measurements, and to evaluate the influence of hand posture; to determine the relationship of hand bone mineral density (BMD) to generalized osteopenia in rheumatoid arthritis (RA); and to determine the relationship between hand BMD and disease severity in early RA.
Methods: Hand BMD was measured by dual-energy x-ray absorptiometry (DXA). We studied 70 postmenopausal women with steroid-treated RA (established RA), ages 49-79, and 20 age-matched healthy controls to determine the relationship to generalized osteoporosis; we also studied 20 patients aged 23-74 years with early RA to determine the relationship between disease severity and hand BMD.
Results: Reproducibility of hand BMD was to within 1%. In established RA, there was a greater decrease in juxtaarticular BMD (23% at the hand) than in generalized BMD (16% at the femoral neck, 11% at the lumbar spine, and 11% total body) compared with that in age-matched controls. Hand BMD correlated with skeletal size and BMD at other skeletal sites. In established RA, there was no effect of disease duration, disability, or steroid therapy. In early RA, hand BMD correlated with age and disease activity.
Conclusion: Measurement of hand BMD by DXA is accurate and precise. Hand BMD reflects BMD at other skeletal sites in patients with RA, and is a marker of disease severity in patients with early disease. It may be a sensitive marker of disease progression and response to therapeutic intervention.