Does active treatment of rheumatoid arthritis limit disease-associated bone loss?

Generalized bone loss in rheumatoid arthritis (RA) is multi-factorial, with the inflammatory disease itself thought to contribute to bone loss. To study the extent to which control of disease activity affects bone turnover in RA and whether treatment with disease-modifying anti-rheumatic drugs (DMARDs) reduces bone turnover and loss of bone mass, we measured bone density and biochemical markers of bone resorption in a group of patients with active RA starting on DMARDS.

Patients with active RA were enrolled on starting a new DMARD. Patients were mobile and none took steroids or any treatment for osteoporosis. Clinical and laboratory measures of disease activity were made at 3-monthly intervals and an index of disease activity (DAS) calculated. Bone density was assessed at 0, 1 and 2 yr (Hologic QDR 4500c). Urinary deoxypyridinoline (D-PYR) and pyridinoline (PYR) were measured by ELISA at 0, 3, 6, 9 and 12 months.

Forty patients were enrolled, mean age 59.5 (range 31-76), 26 female, 14 male, 25 had established RA, 15 had RA for <2 yr. Baseline D-PYR was elevated (8.4+/-4.55 nmol/mmol creatinine) and correlated with ESR (r=0.6, P<0.01) and DAS (r=0.4, P<0.05). On treatment ESR and DAS fell by 38.5 and 29.3%, respectively. D-PYR was reduced by 12.3% by 9 months (P<0.01). Spearman rank order correlation showed ESR to be the most significant determinant of D-PYR over 1 yr (r=0.43, P<0.001). Serial bone density was available on 21 patients. There was no significant change in BMD over the 2 yr. The change in DAS over 0-3 months showed an inverse relationship with the percent change in spine over 1 yr (r=-0.5, P=0.05). The change in D-PYR over 0-3 months was not closely related to the change in BMD at hip or spine at 1 yr.

Disease activity is a significant determinant of bone turnover in RA. Bone resorption markers fall on treatment of RA with DMARDs and no change in BMD was demonstrated at 2 yr. This study suggests the need to control disease activity in RA in order to prevent systemic bone loss.