Quantitative ultrasound (QUS) of the calcaneus may be a promising noninvasive triage tool to rule out low bone mineral density (BMD) in adults with axial spondyloarthropathy, according to study results published in Clinical Rheumatology.

In this observational cross-sectional twin-center study, researchers examined whether QUS, a more portable and less invasive option to assess bone health, compared with dual-energy x-ray absorptiometry (DXA) scanning, is useful for osteoporosis screening in axial spondyloarthropathy. Older men and postmenopausal women with axial spondyloarthropathy were consecutively recruited from dedicated spondylitis and general rheumatology clinics (n=56). A DXA scanner was used to assess BMD at the spine and hip. Broadband ultrasound attenuation, speed of sound, stiffness index, and T-scores were collected from a QUS of the right calcaneus. Researchers used receiver-operating characteristics curve analysis to determine the ability of QUS to discriminate between low and normal BMD.

In this analysis, all QUS parameters had the ability to discriminate between a diagnosis of low and normal BMD in any site (area under the curve range, 0.695-0.779). In further analysis, the researchers established thresholds for QUS values above which there was a 90% certainty that a patient did not have low BMD. They found that the broadband ultrasound attenuation threshold had the highest sensitivity (93%), specificity (55%), and negative predictive value (86%) of the 4 QUS variables. Using this triage strategy, up to 27% of DXA scans could have been saved in patients with values above this threshold who were considered low risk of having BMD at any site.


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This study was limited by the low prevalence of both osteoporosis and fragility fractures, which prohibited any analysis of the role of QUS in either. An analysis of cost effectiveness was also not performed for QUS vs DXA. Furthermore, the thresholds established in this study were device-specific; caution should be exercised when extrapolating these results to other devices. In this study, clinical risk factors were not taken into consideration; if used for detection of low BMD, QUS results should be interpreted in the context of a wider clinical picture.

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“We found that QUS of the calcaneus could identify participants without low BMD at any site (ie, T-score <−1 at hip and/or spine) with 90% confidence,” the researchers concluded. “One benefit of introducing a ‘triage’ tool is a reduction in the demand on DXA, a resource which is heavily oversubscribed… In this study, using QUS to out rule a diagnosis of low BMD could have avoided up to 27% of DXAs. This has the potential to significantly ease the strain on the service.” They added that “[f]urther research is needed to delineate the role of QUS in confidently diagnosing osteoporosis in this population.”

Disclosure: One author was the recipient of a scholarship funded by AbbVie pharmaceuticals. Please see the original reference for a full list of disclosures.

Reference

Fitzgerald GE, Anachebe T, McCarroll KG, O’Shea F. Calcaneal quantitative ultrasound has a role in out ruling low bone mineral density in axial spondyloarthropathy [published online January 17, 2020]. Clin Rheumatol. doi:10.1007/s10067-019-04876-9