OSTEOPOROSIS IN RHEUMATOID-ARTHRITIS - FINDINGS IN THE METACARPAL, SPINE, AND HIP AND A STUDY OF THE DETERMINANTS OF BOTH LOCALIZED AND GENERALIZED OSTEOPENIA

Objective. To determine the relationship between axial and peripheral bone density in patients with rheumatoid arthritis (RA) compared to co ntrols. To study risk factors for axial and peripheral bone loss in RA . Methods, Twenty women with RA and 20 age matched controls underwent dual energy x-ray absorptiometry (DXA) of the spine and hip and micror adioscopy of the hands in order to quantify the combined cortical thic kness (CCT) of the 2nd metacarpal. Sharp's method was used to assess t he degree of joint space narrowing and erosions. Results, Compared to controls, the RA group had significantly decreased bone density at the hip (0.761 g/cm(2) vs 0.852 g/cm(2), p < 0.05) and at the 2nd metacar pal (3.77 vs 4.39 mm, p < 0.05), but not at the spine (0.960 vs 0.947 g/cm(2), NS). In patients with RA, measurement of the CCT did not pred ict bone density at the spine or hip (r = 0.07, NS, and r = 0.095, NS, respectively), whereas in controls, the CCT was significantly correla ted with bone density at both these axial sites (r = 0.47, p < 0.05, a nd r = 0.64, p < 0.01, respectively). Grip strength in RA was correlat ed with the CCT (r = 0.62, p < 0.01), implying a relationship between hand function and local bone density. Sharp's method did not correlate with axial bone density, but it was strongly correlated with the CCT (r = -0.64, p < 0.01). Conclusion, In RA, the CCT is not a useful scre en for osteoporosis at the spine or hip. This suggests that localized and generalized osteopenia in RA are best viewed as independent proces ses.