Tsampalieros A, Berkenstock M K, Zemel B S, Griffin L, Shults J, Burnham J M, Baldassano R N, Leonard M B
Department of Pediatrics, The Children's Hospital of Eastern Ontario, Faculty of Medicine, University of Ottawa, 401 Smyth Road, Ottawa, ON, K1H 8 L1, Canada,
Osteoporos Int. 2014 Jul;25(7):1875-83. doi: 10.1007/s00198-014-2701-x. Epub 2014 Apr 24.
This study of changes in dual energy x-ray absorptiometry (DXA) spine BMD following diagnosis and treatment for childhood Crohn's disease demonstrated that changes in conventional posteroanterior BMD results were confounded by impaired growth, and suggested that lateral spine measurements and strategies to estimate volumetric BMD were more sensitive to disease and treatment effects.
We previously reported significant increases in peripheral quantitative CT (pQCT) measures of trabecular volumetric bone mineral density (vBMD) following diagnosis and treatment of pediatric Crohn's disease (CD). The objective of this study was to compare pQCT trabecular vBMD and three DXA measures of spine BMD in this cohort: (1) conventional posteroanterior BMD (PA-BMD), (2) PA-BMD adjusted for height Z (PA-BMDHtZ), and (3) width-adjusted volumetric BMD (WA-BMD) estimated from PA and lateral scans.
Spine DXA [lumbar (L1-4) for posteroanterior and L3 for lateral] and tibia pQCT scans were obtained in 65 CD subjects (ages 7-18 years) at diagnosis and 12 months later. BMD results were converted to sex, race, and age-specific Z-scores based on reference data in >650 children (ages 5-21 years). Multivariable linear regression models identified factors associated with BMD Z-scores.
At CD diagnosis, all BMD Z-scores were lower compared with the reference children (all p values <0.01). The pQCT vBMD Z-scores (-1.46 ± 1.30) were lower compared with DXA PA-BMD (-0.75 ± 0.98), PA-BMDHtZ (-0.53 ± 0.87), and WA-BMD (-0.61 ± 1.10) among CD participants. Only PA-BMD Z-scores were correlated with height Z-scores at baseline (R = 0.47, p < 0.0001). pQCT and WA-BMD Z-scores increased significantly over 12 months to -1.04 ± 1.26 and -0.20 ± 1.14, respectively. Changes in all four BMD Z-scores were positively associated with changes in height Z-scores (p < 0.05). Glucocorticoid doses were inversely associated with changes in WA-BMD (p < 0.01) only.
Conventional and height Z-score-adjusted PA DXA methods did not demonstrate the significant increases in trabecular vBMD noted on pQCT and WA-BMD scans. WA-BMD captured glucocorticoid effects, potentially due to isolation of the vertebral body on the lateral projection. Future studies are needed to identify the BMD measure that provides greatest fracture discrimination in CD.
这项关于儿童克罗恩病诊断和治疗后双能X线吸收测定法（DXA）脊柱骨密度（BMD）变化的研究表明，传统前后位BMD结果的变化受到生长受损的混淆，并表明脊柱侧位测量和估计体积BMD的策略对疾病和治疗效果更敏感。
我们之前报告了儿童克罗恩病（CD）诊断和治疗后小梁体积骨密度（vBMD）的外周定量CT（pQCT）测量值显著增加。本研究的目的是比较该队列中pQCT小梁vBMD和三种DXA脊柱BMD测量值：（1）传统前后位BMD（PA-BMD），（2）根据身高Z评分调整的PA-BMD（PA-BMDHtZ），以及（3）根据前后位和侧位扫描估计的宽度调整体积BMD（WA-BMD）。
对65名CD受试者（7 - 18岁）在诊断时和12个月后进行脊柱DXA扫描[前后位为腰椎（L1 - 4），侧位为L3]和胫骨pQCT扫描。根据650多名儿童（5 - 21岁）的参考数据，将BMD结果转换为性别、种族和年龄特异性Z评分。多变量线性回归模型确定与BMD Z评分相关的因素。
在CD诊断时，所有BMD Z评分均低于参考儿童（所有p值<0.01）。CD参与者中，pQCT vBMD Z评分（-1.46±1.30）低于DXA PA-BMD（-0.75±0.98）、PA-BMDHtZ（-0.53±0.87）和WA-BMD（-0.61±1.10）。仅PA-BMD Z评分在基线时与身高Z评分相关（R = 0.47，p < 0.0001）。pQCT和WA-BMD Z评分在12个月内显著增加至-1.04±1.26和-0.20±1.14， respectively。所有四个BMD Z评分的变化与身高Z评分的变化呈正相关（p < 0.05）。糖皮质激素剂量仅与WA-BMD的变化呈负相关（p < 0.01）。
传统的和根据身高Z评分调整的PA DXA方法未显示出pQCT和WA-BMD扫描中观察到的小梁vBMD的显著增加。WA-BMD捕捉到了糖皮质激素的影响，可能是由于在侧位投影上椎体的孤立。未来需要进行研究以确定在CD中提供最大骨折辨别能力的BMD测量方法。
