The development of bone mineral density and the occurrence of osteoporosis from 15 to 20 years of disease onset in patients with rheumatoid arthritis.

OBJECTIVE: To ascertain the occurrence of osteoporosis and the development of central bone mineral density (BMD) in long-term rheumatoid arthritis (RA)
METHODS: BMD of the lumbar spine (L2-L4) and the femoral neck were measured by dual-energy X-ray absorptiometry in a cohort of 59 patients (49 women and 10 men) with rheumatoid factor-positive RA followed up for 20 years. BMD measurements were obtained at the 15- and 20-year follow-up visits.
RESULTS: At the 15-year check-up the mean age was 61 (SD 13)for men and 54 (SD 11) years for women. Bone densitometry of these patients revealed decreased BMD at both lumbar spine and femoral neck, the mean T-scores being -1.1 [95%CI: -1.6 to -0.6] and -1.3 [95%CI: -1.6 to -1], respectively). Eighteen (31 %) patients thus had osteoporosis (BMD T -score < or = -2.5) and 32 (54%) patients were osteopenic (BMD T-score -1.0 to -2.5). However, when compared with reference values, the decreases in central bone mineral in this patient group were of low degree; the mean Z-score -0.2 [95%CI: -0.7 to 0.2] at the lumbar spine and -0.5 [95%CI: -0.8 to -0.3] at the femoral neck, respectively. After the subsequent five years the mean Z-score increased 0.45 [95%CI: 0.32 to 0.58] at the lumbar spine and the mean T-score decreased -0.20 [95%CI: -0.32 to -0.08] at the femoral neck. ESR, Larsen score, gender and cumulative dose of prednisolone during the 5 year follow-up and HAQ-index were used as explanatory parameters of BMD change between the 15- and 20-year follow-ups. None of these parameters explained the BMD change.
CONCLUSION: We conclude that in long-term RA central bone densities seemed to be only moderately decreased after 15 years from eruption of RA. No essential change in central BMD was found after the consecutive 5 years.