Osteoporosis with low dose corticosteroids: contribution of underlying disease effects and discriminatory ability of ultrasound versus bone densitometry.

OBJECTIVE: Corticosteroid use is associated with rapid bone loss, but the effect of low dose corticosteroids (CS) remains controversial and the extent to which increased fracture risk relates to quantitative effects, as reflected by change in bone mineral density (BMD), or to qualitative effects due to altered microarchitecture is unclear. Moreover the contribution of the underlying disease, for which CS are used, confounds the assessment of CS effects on bone. Our aim was to examine these effects of CS on bone.
METHODS: We measured BMD, quantitative ultrasound (US), and clinical and radiological disease indices in 76 patients with rheumatoid arthritis (RA) treated with or without low dose CS. Disease effects were quantitated using the Health Assessment Questionnaire and radiological scores.
RESULTS: BMD and US measures were significantly reduced in RA patients compared to age matched controls. Low dose CS use was associated with a further small but nonsignificant reduction in BMD, and US measures did not further discriminate CS effects on bone. Radiological score was an independent predictor of US measures, suggesting that in RA, calcaneal bone may reflect both systemic and local disease effects.
CONCLUSION: US did not appear to discriminate effects of low dose CS on bone better than BMD. However, underlying RA disease effects on bone are detectable by US. Quantitative US should be investigated for its utility in assessing disease activity or progress in RA.