To study bone mass and the factors that influence bone mass in rheumatoid arthritis patients versus controls.
85 patients (73 women) with a mean age of 57 +/- 11 years and a mean disease duration of 13 +/- 9 years were compared to 85 age- and sex-matched controls. Among the patients, 62 (76%) had positive rheumatoid factor tests and 51 (60%) were receiving steroid therapy, with a mean daily dose of 10 +/- 4 mg and a mean duration of 7 +/- 6 years. The following parameters were determined: morning stiffness duration, painful and swollen joint counts, Lee's and Ritchie's indices, Health Assessment Questionnaire score, erythrocyte sedimentation rate, and C-reactive protein. Bone mineral density was measured at the lumbar spine and femoral neck using dual-energy X-ray absorptiometry (Sophos L-XRA).
In the nonsteroid-treated patients, bone mineral density was similar to that in controls at the lumbar spine but was decreased by 8% (95% confidence interval [CI], 1.8-14.2%) at the femoral neck (0.76 +/- 0.14 g/cm2 versus 0.83 +/- 0.15 g/cm2; P = 0.03). Decreases of 11.5% (95% CI, 8.1-14.9%) at the lumbar spine and 10.4% (95% CI, 6.4-14.4%) at the femoral neck were found in the steroid-treated patients versus the nonsteroid-treated patients. In the patient group, femoral neck bone mineral density was significantly negatively correlated with age (r = -0.5), the Heath Assessment Questionnaire score (r = -0.27), and the erythrocyte sedimentation rate (r = -0.25), whereas only the first two variables were significantly correlated with lumbar bone mineral density. A multiple linear regression model including age, glucocorticoid use, rheumatoid factor, the Health Assessment Questionnaire score, and the erythrocyte sedimentation rate was constructed and adjusted for the number of variables. This model explained 44.7% of the variance of femoral neck bone mineral density.
Rheumatoid arthritis is associated with a decrease in bone mass that is most marked in patients with active and/or severe disease and in those who take glucocorticoids.