Change in ultrasound-assessed speed of sound at the tibia and distal radius as a function of age: The Canadian Multicentre Osteoporosis Study.

Abstract

Introduction Speed of sound (SOS in m/s) measured with the BeamMed Sunlight Multi-site quantitative ultrasound (QUS) can predict fracture in women over a five-year period, independent of bone mineral density and other significant risk factors for fracture. The rate of SOS decline may better identify patients with an elevated risk for fracture than a single SOS measurement. Objectives To assess the average rate of change in SOS as a function of age among Canadians 30-90y, stratified by sex. Methods This investigation included all participants of the Canadian Multicenter Osteoporosis Study (CaMOS) with two SOS measurements approximately five years apart, allowing for calculation of rate of change. SOS measurements were at the distal radius (DR) and tibia (TIB) sites. Participants were grouped in 10-year bands according to baseline age (≤40 y, >40-50y, >50-60y, >60-70y, >70-80y and >80y) and mean five-year rates of change were calculated. All changes were normalized to five-year rates. Standard descriptive and comparative statistics were employed. Results There were 720 participants (211 men and 509 women) with SOS measurements at the DR and/or TIB sites at baseline and approximately five years later (mean 1841 days; SD 68.5 days). The mean (SD) change over the five-year follow-up at the DR was -83.7 m/s (112.2) and at the TIB was -17.1 m/s (114.8). Please see the table for the mean (SEM) changes in SOS over the age groups. There were no significant differences in the mean change in DR SOS in the total, men or women's sites among the age groups, although there was a trend for a decreasing DR at the approximate time of menopause in the women's group. At the TIB site, there were also no significant differences in mean change in SOS among the age groups for the total and men's groups, but there were significant differences (p Conclusions There were clear trends in the data that men had a relatively stable loss in SOS, whereas women tended to have a greater loss in the age group most associated with menopause. The relatively small sample size of men as compared to women may have limited the power to detect differences among groups in men. Use of antiresorptive therapy during the observation period may also be a confounding factor. However, the overall trend is one of almost-consistent loss of SOS at all age groups, as to be expected following the attainment of peak bone mass.