Is calcaneal quantitative ultrasound useful as a prescreen stratification tool for osteoporosis?

Calcaneal quantitative ultrasound (QUS) is attractive as a prescreening tool for osteoporosis, alternative to dual-energy X-ray absorptiometry. We investigated the literature of the usability of calcaneal QUS. We found large heterogeneity between studies and uncertainty about cutoff, device, and measured variable. Despite osteoporosis-related fractures being a major health issue, osteoporosis remains underdiagnosed. Dual-energy X-ray absorptiometry (DXA) of the hip or spine is currently the preferred method for diagnosis of osteoporosis, but the method is limited by low accessibility. QUS is a method for assessing bone alternative to DXA. The aim of this systematic review was to explore the usability of QUS as a prescreen stratification tool for assessment of osteoporosis. Studies that evaluated calcaneal QUS with DXA of the hip or spine as the gold standard was included. We extracted data from included studies to calculate number of DXAs saved and misclassification rates at cutoffs equal to high sensitivity and/or specificity. The number of DXAs saved and percentage of persons misclassified were measures of usability. We included 31 studies. Studies were heterogeneous regarding study characteristics. Analyses showed a wide spectrum of percentage of DXAs saved (2.7-68.8%) and misclassification rates (0-12.4%) depending on prescreen strategy and study characteristics, device, measured variable, and cutoff. Calcaneal QUS is potentially useful as a prescreen tool for assessment of osteoporosis. However, there is no consensus of device, variable, and cutoff. Overall, there is no sufficient evidence to recommend a specific cutoff for calcaneal QUS that provides a certainty level high enough to rule in or out osteoporosis. Calcaneal QUS in a prescreen or stratification algorithm must be based on device-specific cutoffs that are validated in the populations for which they are intended to be used.