Calcaneal quantitative ultrasound has a role in out ruling low bone mineral density in axial spondyloarthropathy.

Objective: The aim of this study was to investigate the role of quantitative ultrasound (QUS) of the calcaneus in screening for osteoporosis in adults with axial spondyloarthropathy (axSpA).

Method: Postmenopausal women and men over 50 years with axSpA were recruited for this observational cross-sectional study. Dual-energy x-ray absorptiometry (DXA) assessed bone mineral density (BMD) of the spine and hip. QUS of the calcaneus produced broadband ultrasound attenuation (BUA), speed of sound (SOS), stiffness index (SI), and T-scores. Receiver-operating characteristics (ROC) curve analysis determined the ability of QUS to discriminate between low and normal BMD. Thresholds were identified to (1) out rule low BMD, (2) identify osteoporosis, and (3) identify low BMD. The number of DXAs which could be avoided using this approach was calculated.

Results: 56 participants were analyzed. BUA, SI, and T-score QUS parameters correlated with BMD by DXA; SOS did not. All QUS parameters had the ability to discriminate between low and normal BMD (area under the curve varied from 0.695 to 0.779). QUS identified individuals without low BMD with 90% confidence, with BUA performing best (sensitivity 93%, negative predictive value 86%). Using QUS as a triage tool, up to 27% of DXA assessments could have been avoided. QUS could not confidently identify individuals with osteoporosis.

Conclusions: QUS of the calcaneus confidently out ruled low BMD in individuals with axSpA, reducing the need for onward DXA referral by up to 27%. QUS is promising as a non-invasive triage tool in the assessment of osteoporosis in adults with axSpA.Key Points• Osteoporosis is common in axial spondyloarthropathy (SpA), but evaluation of bone health is suboptimal in this population.• Quantitative ultrasound (QUS) of the calcaneus can out rule low bone mineral density in individuals with axial SpA, reducing the need for DXA assessment.• QUS is a promising non-invasive triage tool in the assessment of bone health in axial SpA.