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Quantitative ultrasound and bone mineral density: discriminatory ability in patients with rheumatoid arthritis and controls with and without vertebral deformities

R E Ørstavik¹, G Haugeberg¹, T Uhlig¹, P Mowinckel¹, T K Kvien¹, J A Falch², J I Halse³

¹ Oslo City Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway
² Department of Internal Medicine, Aker Hospital, Oslo
³ Clinic of Osteoporosis, Oslo

Correspondence to:
Correspondence to:
Dr Ragnhild Ørstavik
Department of Rheumatology, Diakonhjemmet Hospital, Box 23, Vinderen, N-0319 Oslo, Norway; ragnhild.orstavik{at}ioks.uio.no

Background: Quantitative ultrasound (QUS) is a reliable tool for discriminating between subjects with and without vertebral deformities in postmenopausal osteoporosis. Less is known about osteoporosis caused by inflammatory diseases or corticosteroid use.

Objectives: (1) To compare in patients with rheumatoid arthritis the ability of QUS and dual energy x ray absorptiometry (DXA) to discriminate between those with and without vertebral deformities; (2) to explore whether the results are similar in population based controls.

Methods: Standardised lateral radiographs of the spine were obtained from 210 patients with rheumatoid arthritis aged over 50 years and 210 individually matched controls. Vertebral deformities were assessed morphometrically and semiquantitatively. All participants underwent bone measurements by DXA (Lunar Expert) and QUS (Lunar Achilles+). Receiver operating curve (ROC) analysis was used to compare the discriminating ability of BMD and QUS measurements in patients and controls with and without vertebral deformities. Analyses were repeated in patients stratified according to corticosteroid use.

Results: For all bone measurements except lumbar spine in the rheumatoid arthritis group, BMD discriminated significantly between the patients with and without vertebral deformities, and the results were similar to those obtained in controls. Among current corticosteroid users, neither QUS nor DXA could discriminate between subjects with and without vertebral deformities.

Conclusions: These findings support QUS as an alternative tool for identifying patients at risk of having vertebral deformities in rheumatoid arthritis, although results should be interpreted with caution in current users of corticosteroids.

Abbreviations: ACR, American College of Rheumatology; BMD, bone mineral density; BUA, broadband ultrasound attenuation; DAS, disease activity score; DXA, dual energy x ray absorptiometry; ORAR, Oslo rheumatoid arthritis register; QUS, quantitative ultrasound; SI, stiffness index; SOS, speed of sound

Keywords: quantitative ultrasound; osteoporosis; rheumatoid arthritis; vertebral deformities

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