Blomquist Gustav A, Davenport Daniel L, Mawad Hanna W, Monier-Faugere Marie-Claude, Malluche Hartmut H
Clin Nephrol. 2016 Feb;85(2):77-83. doi: 10.5414/CN108708.
Currently, there is no consensus whether dual-energy X-ray absorptiometry (DXA) or quantitative computed tomography (QCT) can be used to screen for osteoporosis or osteopenia in CKD-5D patients. This study uses iliac bone histology, the "gold standard" for bone volume evaluation, to determine the utility of DXA and QCT for low bone mass screening in CKD-5D patients.
A cross-sectional study of patients with CKD-5D employing iliac crest bone biopsies to assess bone volume by histology and comparing results to bone mineral density (BMD) measurements of the hip and spine by DXA and QCT. Pearson's correlation, linear regression, and receiver operating characteristics curve analyses were performed.
46 patients (mean age 51 years, 52% women, median dialysis vintage 46 months) had bone biopsies, DXA, and QCT scans. 37 patients (80%) had low bone volume by histology. DXA and QCT BMD values (g/cm2) were very highly correlated at the femoral neck (ρ = 0.97) and total hip (ρ = 0.97), and to a lesser degree at the spine (ρ = 0.65). DXA and QCT t-scores were also highly correlated, but QCT t-scores were systematically greater than DXA t-scores (1.1 S.D. on average at the femoral neck) leading to less recognition of osteopenia and osteoporosis by QCT. A t-score below -1 by DXA at the femoral neck (i.e., osteopenic or osteoporotic) showed 83% sensitivity and 78% specificity relative to low bone volume by histology. A QCT t-score below -1 did not reach acceptable diagnostic levels of sensitivity and specificity.
DXA and QCT provide nearly identical areal BMD measures at the hip. However, QCT t-scores are consistently higher than DXA t-scores resulting in less diagnosis of osteoporosis or osteopenia. DXA results showed acceptable diagnostic sensitivity and specificity for low bone volume by histology and can be used for diagnosis of osteopenia and osteoporosis in patients with CKD-5D.
目前，对于双能X线吸收法（DXA）或定量计算机断层扫描（QCT）能否用于筛查慢性肾脏病5期（CKD-5D）患者的骨质疏松或骨质减少，尚无共识。本研究采用髂骨组织学检查（评估骨量的“金标准”）来确定DXA和QCT在CKD-5D患者低骨量筛查中的效用。
一项针对CKD-5D患者的横断面研究，采用髂嵴骨活检通过组织学评估骨量，并将结果与通过DXA和QCT测量的髋部和脊柱骨密度（BMD）进行比较。进行了Pearson相关性分析、线性回归分析和受试者工作特征曲线分析。
46例患者（平均年龄51岁，52%为女性，透析中位时间46个月）接受了骨活检、DXA和QCT扫描。37例患者（80%）组织学检查显示骨量低。DXA和QCT的BMD值（g/cm²）在股骨颈（ρ = 0.97）和全髋（ρ = 0.97）高度相关，在脊柱相关性稍低（ρ = 0.65）。DXA和QCT的t值也高度相关，但QCT的t值系统性地高于DXA的t值（在股骨颈平均高1.1个标准差），导致QCT对骨质减少和骨质疏松的识别率较低。股骨颈DXA的t值低于-1（即骨质减少或骨质疏松）时，相对于组织学检查显示的低骨量，敏感性为83%，特异性为78%。QCT的t值低于-1未达到可接受的诊断敏感性和特异性水平。
DXA和QCT在髋部提供的面积骨密度测量结果几乎相同。然而，QCT的t值始终高于DXA的t值，导致骨质疏松或骨质减少的诊断较少。DXA结果显示对组织学检查显示的低骨量具有可接受的诊断敏感性和特异性，可用于CKD-5D患者骨质疏松和骨质减少的诊断。
