Bone mineral density in systemic lupus erythematosus: comparison with rheumatoid arthritis and healthy controls.

OBJECTIVES To examine bone mineral density (BMD) frequency of osteoporosis and reduced bone mass in systemic lupus erythematosus (SLE), and compare the data of the SLE patients with matched rheumatoid arthritis (RA) patients and healthy controls. Secondly, to study possible correlations between BMD, demographic and disease variables in the SLE patients. METHODS Measures of BMD assessed by dual energy x ray absorptiometry were obtained from 75 SLE patients aged </= 70 years, 75 RA patients matched for age, sex and disease duration, and from 75 healthy controls matched for age, sex and geographical area. Disease activity and accumulated organ damage were assessed in the SLE patients. RESULTS The SLE patients had significantly lower BMD values at lumbar spine L2-L4 and hip, and higher frequency of osteoporosis at all sites of measurement compared with matched healthy controls. The matched SLE and RA patients had similar BMD, prevalence of osteoporosis and reduced bone mass. In the SLE patients BMD was more strongly correlated with accumulated organ damage than with markers of disease activity or duration. In multivariate analyses BMD was at all sites predicted by age and body mass, at lumbar spine also by the current corticosteroid dose. CONCLUSION The study showed reduced BMD in patients with SLE compared with matched healthy controls. Premenopausal women taking corticosteroids were especially affected. Furthermore, the BMD of matched SLE and RA patients was reduced to a similar extent.