Association Between Linear Growth and Bone Accrual in a Diverse Cohort of Children and Adolescents

Abstract

Importance: Prevention of osteoporosis in adulthood begins with optimizing bone health in early life. The longitudinal association between growth and bone accretion during childhood is not fully understood.

Objectives: To assess the acquisition of whole-body (WB) and skeletal site-specific bone mineral content (BMC) relative to linear growth in a healthy, diverse, longitudinal cohort of children, adolescents, and young adults and to test for differences related to sex and African American race.

Design, setting, and participants: This investigation was a mixed longitudinal study with annual assessments for up to 7 years at 5 US clinical centers. Participants were healthy children, adolescents, and young adults. The study dates were July 2002 through March 2010. The dates of the analysis were June through December 2016.

Main outcomes and measures: Anthropometrics, BMC, and body composition via dual-energy x-ray absorptiometry. The superimposition by translation and rotation (SITAR) analysis method was used to define the mean trajectories for height, WB lean soft tissue, appendicular lean soft tissue, and WB and skeletal site-specific BMC acquisition and to measure the age and magnitude of peak velocity for each parameter. The SITAR modeling was performed separately by sex and self-reported race.

Results: Among 2014 healthy children, adolescents, and young adults (1022 [50.7%] female and 479 [23.8%] African American) aged 5 to 19 years at study entry, the mean age of peak height velocity was 13.1 years (95% CI, 13.0-13.2 years) in African American boys vs 13.4 years (95% CI, 13.3-13.4 years) in non-African American boys (difference, -0.3 years; 95% CI, -0.4 to -0.1 years) and 11.0 years (95% CI, 10.8-11.1 years) in African American girls vs 11.6 years (95% CI, 11.5-11.6 years) in non-African American girls (difference, -0.6 years; 95% CI, -0.7 to -0.5 years). Age of peak acquisition of WB BMC was 14.0 years (95% CI, 13.8-14.1 years) in African American boys vs 14.0 years (95% CI, 13.9-14.1 years) in non-African American boys (difference, -0.0 years; 95% CI, -0.2 to 0.2 years) and 12.1 years (95% CI, 12.0-12.3 years) in African American girls vs 12.4 years (95% CI, 12.3-12.5 years) in non-African American girls (difference, -0.3 years; 95% CI, -0.4 to -0.1 years). At age 7 years, children had acquired 69.5% to 74.5% of maximal observed height but only 29.6% to 38.1% of maximal observed WB BMC. Adolescents gained 32.7% to 35.8% of maximal observed WB BMC during the 2 years before and 2 years after peak height velocity. Another 6.9% to 10.7% of maximal observed WB BMC occurred after linear growth had ceased. In the group at highest risk for fracture, non-African American boys, peak fracture incidence occurred approximately 1 year before peak height velocity.

Conclusions and relevance: In this longitudinal study, height gains substantially outpaced gains in BMC during childhood, which could contribute to fracture risk. A significant proportion of bone is accrued after adult height is achieved. Therefore, late adolescence represents a potentially underrecognized window of opportunity to optimize bone mass.

Figure 1

Acquisition of Height, Bone, and Soft Tissue With Age, by Sex and Self-reported Race, From the Mean Curves Modeled Using SITAR (Superimposition by Translation and Rotation) A, The SITAR-derived mean curves for the magnitude of acquisition of each growth parameter with increasing age are shown, stratified by sex and race. B, The SITAR-derived mean curves for the velocity of acquisition of each growth parameter with increasing age are shown, stratified by sex and race. In B, the horizontal black line indicates zero velocity (ie, neither gain nor loss). aLST indicates appendicular lean soft tissue; BMC, bone mineral content; WB, whole body; and WB LST, whole-body lean soft tissue.

Figure 2

Relative Timing and Magnitude of Peak Height Velocity (PHV) and Peak Whole-Body Bone Mineral Content (WB BMC) Acquisition, by Sex and Self-reported Race In each panel, the solid vertical line indicates the age of PHV, and the dashed vertical line indicates the age of peak WB BMC acquisition. The ages at which peak velocity in each of these parameters occurs, along with the lag between the 2, are also given. The 2 years before and 2 years after the PHV are shaded in gray. PBMCV indicates peak (whole-body) bone mineral content velocity.