Zemel Babette S, Wasserman Halley, Kelly Andrea, Fan Bo, Shepherd John, Lappe Joan, Gilsanz Vicente, Oberfield Sharon, Winer Karen K, Kalkwarf Heidi J
Division of Gastroenterology, Hepatology and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, United States of America; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States of America.
Division of Endocrinology, Cincinnati Children's Hospital Medical Center, Cincinnati, United States of America; Department of Pediatrics, University of Cincinnati College of Medicine, United States of America.
Bone. 2020 Dec;141:115581. doi: 10.1016/j.bone.2020.115581. Epub 2020 Aug 11.
Bone mineral content (BMC) and areal-bone mineral density (aBMD) measurements of the lumbar spine (LS) and whole body less head (WBLH) by dual energy X-ray absorptiometry (DXA) are recommended for bone health assessment in children. Intermachine differences were not considered previously in formulating these recommendations.
DXA measurements of the LS, WBLH, total hip, femoral neck and distal 1/3 radius from the Bone Mineral Density in Childhood Study were examined. Healthy children, ages 6 to 16 years, from five clinical centers participated. The same spine, whole body, and femur phantoms were measured on each Center's DXA machine. Percentage of individuals with low BMC or aBMD (Z-score < -1.5) was determined. Clinical center differences were evaluated by analysis of covariance adjusting for height and BMI Z-score, calcium intake, physical activity, Tanner stage and bone age. Logistic regression assessed odds of low BMC or aBMD across clinical centers.
Significant differences among Clinical Centers (p < 0.05) were evident in adjusted mean BMC and aBMD Z-scores (n = 1503) for all skeletal sites. WBLH BMC and aBMD Z-scores had the greatest range across centers (-0.13 to 0.24, and -0.17 to 0.56, respectively). The percentage of children with Z-scores less than -1.5 varied among Clinical Centers from 1.9 [95%CI 0.8, 4.5] to 8.1 [95%CI 5.7, 11.3] for WBLH BMC, 1.1 [95%CI 0.4, 3.5] to 6.3 [95%CI 3.8, 10.1] for WBLH aBMD, and from 4.4 [95%CI 2.8, 7.0] to 12.6 [95%CI 9.3, 16.9] for distal 1/3 radius aBMD. For each skeletal site except total hip aBMD and femoral neck BMC, at least one center had significantly lower odds of low bone density.
By design, our reference ranges capture intermachine variability. Most clinical centers don't know where their machine falls within the range of intermachine variability, and this may affect diagnosis of children evaluated for conditions that threaten bone health. Total hip scans showed the least, and whole body scans showed the most intermachine variability. Pediatric bone health assessment recommendations should recognize intermachine differences and address this important issue.
双能X线吸收法（DXA）测量腰椎（LS）和去头部的全身（WBLH）的骨矿物质含量（BMC）和面积骨矿物质密度（aBMD），被推荐用于儿童骨健康评估。在制定这些建议时，之前未考虑不同仪器间的差异。
对儿童骨矿物质密度研究中LS、WBLH、全髋、股骨颈和桡骨远端1/3的DXA测量结果进行检查。来自五个临床中心的6至16岁健康儿童参与其中。在每个中心的DXA仪器上对相同的脊柱、全身和股骨模型进行测量。确定BMC或aBMD较低（Z评分＜ -1.5）的个体百分比。通过协方差分析评估临床中心差异，并对身高和BMI Z评分、钙摄入量、身体活动、坦纳分期和骨龄进行校正。逻辑回归评估各临床中心BMC或aBMD较低的几率。
在所有骨骼部位的校正平均BMC和aBMD Z评分（n = 1503）中，临床中心之间存在显著差异（p ＜ 0.05）。WBLH的BMC和aBMD Z评分在各中心之间的范围最大（分别为 -0.13至0.24和 -0.17至0.56）。Z评分低于 -1.5的儿童百分比在各临床中心有所不同，WBLH的BMC为1.9 [95%CI 0.8, 4.5]至8.1 [95%CI 5.7, 11.3]，WBLH的aBMD为1.1 [95%CI 0.4, 3.5]至6.3 [95%CI 3.8, 10.1]，桡骨远端1/3的aBMD为4.4 [95%CI 2.8, 7.0]至12.6 [95%CI 9.3, 16.9]。除全髋aBMD和股骨颈BMC外，每个骨骼部位至少有一个中心的低骨密度几率显著较低。
按照设计，我们的参考范围涵盖了仪器间的变异性。大多数临床中心不知道其仪器在仪器间变异性范围内的位置，这可能会影响对因威胁骨健康的疾病而接受评估的儿童的诊断。全髋扫描显示的仪器间变异性最小，全身扫描显示的仪器间变异性最大。儿童骨健康评估建议应认识到仪器间差异并解决这一重要问题。
