Lumbar spine bone mineral apparent density in children: Results from the bone mineral density in childhood study

Abstract

Context: Dual-energy X-ray absorptiometry (DXA) is a cornerstone of pediatric bone health assessment, yet differences in height-for-age confound the interpretation of areal bone mineral density (aBMD) measures. To reduce the confounding of short stature on spine bone density, use of bone mineral apparent density (BMAD) and height-for-age Z-score (HAZ).adjusted aBMD (aBMDHAZ) are recommended. However, spine BMAD reference data are sparse, and the degree to which BMAD and aBMDHAZ account for height-related artifacts in bone density remains unclear. Objective: We developed age-, sex-, and population ancestry.specific spine BMAD reference ranges; compared height-adjustment methods in accounting for shorter stature; and assessed the stability of these measures over time. Design: Secondary analysis of data from a previous longitudinal study. Participants: Children and adolescents aged 5 to 19 years at baseline (n = 2014; 922 males; 22% black) from the Bone Mineral Density in Childhood Study. Main Outcome Measures: Lumbar spine BMAD and aBMDHAZ from DXA. Results: Spine BMAD increased nonlinearly with age and was greater in blacks and females (all P < 0.001). Age-specific spine BMAD z-score reference curves were constructed for black and non.black males and females. Overall, both BMAD and aBMDHAZ z scores reduced the confounding influence of shorter stature, but neitherwas consistently unbiased across all age ranges. BothBMAD and aBMDHAZ z scores tracked strongly over 6 years (r = 0.70 to 0.80; all P < 0.001). Conclusion: This study provided robust spine BMAD reference ranges and demonstrated that BMAD and aBMDHAZ partially reduced the confounding influence of shorter stature on bone density.