We estimated peak bone mass (
PBM) in 615 women and 527 men aged 16 to 40 years using longitudinal data from the Canadian Multicentre
Osteoporosis Study (CaMos). Individual rates of change were averaged to find the mean rate of change for each baseline age. The age range for
PBM was defined as the period during which bone mineral density (BMD) was stable.
PBM was estimated via hierarchical models, weighted according to 2006 Canadian Census data. Lumbar spine
PBM (1.046 ± 0.123 g/cm(2)) occurred at ages 33 to 40 years in women and at 19 to 33 years in men (1.066 ± 0.129 g/cm(2)). Total hip
PBM (0.981 ± 0.122 g/cm(2)) occurred at ages 16 to 19 years in women and 19 to 21 years in men (1.093 ± 0.169 g/cm(2)). Analysis of Canadian geographic variation revealed that the levels of
PBM and of mean BMD in those over age 65 sometimes were discordant, suggesting that
PBM and subsequent rates of bone loss may be subject to different genetic and/or environmental influences. Based on our longitudinally estimated
PBM values, the estimated Canadian prevalences of
osteoporosis (T-score < -2.5) were 12.0% (L(1)-L(4)) and 9.1% (total hip) in women aged 50 years and older and 2.9% (L(1)-L(4)) and 0.9% (total hip) in men aged 50 years and older. These were higher than prevalences using cross-sectional
PBM data. In summary, we found that the age at which
PBM is achieved varies by sex and skeletal site, and different reference values for
PBM lead to different estimates of the prevalence of
osteoporosis. Furthermore, lack of concordance of
PBM and BMD over age 65 suggests different determinants of
PBM and subsequent bone loss.