Calcaneal broadband ultrasound attenuation predicts physical capability: EPIC-Norfolk prospective population-based study

Abstract

Background: Calcaneal ultrasound (broadband ultrasound attenuation - BUA), a marker of bone strength, may predict future physical capability and thus provide a strategy to identify individuals at risk of age-related deterioration of health. This study aims to determine if BUA can predict future physical capability among middle-aged and older adults.

Methods: Summary performance scores (SPS), an objective quantification of physical capability, were devised using participants' measures of standing balance, gait speed and timed chair rises. Associations between BUA and SPS, measured at least six years apart, were investigated using univariable and multivariate sex-specific linear and logistic regression, adjusting for confounders.

Results: 5893 participants were included. In men and women, for every five points lower BUA, there was a 0.2-point decrease in SPS. In women, BUA less than one standard deviation below the mean was associated with low physical capability (defined as SPS 3-6); fully adjusted odds ratio (OR) (95 % confidence interval (CI)) 1.35 (1.01-1.84). No association existed among men; OR (95 % CI) 0.84 (0.59-1.19). Significant risk factors for low physical capability in men with baseline low BUA were: older age [OR 5.77]; high BMI [OR 2.85]; lower social class [OR 1.59]; low physical activity [OR 1.64]. Risk factors among women were: older age [OR 5.54]; high BMI [OR 2.08]; lower education [OR 1.42], low physical activity [OR 1.27]; steroid use [OR 2.05]; and stroke [OR 2.74].

Conclusion: BUA may predict future physical capability in older adults. With further validation, BUA could stratify individuals at risk of deterioration in physical health.

Keywords: Bone strength; Broadband ultrasound attenuation; Older adults; Physical capability.