Heilmann P, Wüster C, Prolingheuer C, Götz M, Ziegler R
Department of Internal Medicine I (Endocrinology and Metabolism), University of Heidelberg, Luisenstr 5, Gebäude 8 D-69115, Heidelberg, Germany.
Calcif Tissue Int. 1998 May;62(5):383-7. doi: 10.1007/s002239900449.
Measurement of bone mineral density (BMD) is used for clinical estimation of fracture risk in osteoporosis. The precision of the method is important for the evaluation of true and clinical relevant changes in BMD in patients with osteoporosis. We measured BMD of the forearm in 14 young, healthy probands (10 males, 4 females), aged 24. 6 +/- 1.5 years with five different instruments using dual-energy X-ray absorptiometry (DXA), single-photon absorptiometry (SPA), and peripheral quantitative computed tomography (pQCT). Precision was expressed as the percentage coefficient of variation (CV%). In addition, the standardized CV% (sCV%) and the root mean square standard deviation (rmsSD%) was calculated for long-term precision. CV% ranged from 1.04 (SPA, distal BMD) to 2.75% (pQCT, trabecular BMD) for short-term precision and from 1.49 (DXA, QDR 1000, 1/3-distal BMD) to 4.33% (SPA, ultradistal) for long-term precision, respectively. The results for the rmsSD% were higher but correlated well with the CV%. A change that exceeds 2 radical2 CV% has been considered as being significant. On this basis, 24.0 +/- 5.1% (mean +/- SEM) of the participants in our study would be expected to have a significant change in BMD without any correlation to the time-delay between the two measurements. Measurements of BMD were done at two locations with all five instruments: ultradistal and middistal BMD using DXA and SPA and total and trabecular BMD using pQCT, respectively. Coefficients of correlation for "between-instrumental" correlation were greater than 0.5 for almost all instruments. Distal and ultradistal BMD measured by SPA and trabecular and total BMD measured by pQCT correlated better with ultradistal BMD measured by DXA. Correspondingly, "within-instrumental" correlation was better for pQCT and SPA than for DXA. The coefficients of correlation between the different DXA methods were greater than 0.95 when corresponding locations were compared. We conclude that the clinical value of monitoring bone loss by measurement of forearm BMD is compromised by the low precision which was seen for DXA methods as well as for SPA and even pQCT in young healthy controls.
骨密度（BMD）测量用于临床评估骨质疏松症的骨折风险。该方法的精密度对于评估骨质疏松症患者BMD的真实且临床相关变化至关重要。我们使用双能X线吸收法（DXA）、单光子吸收法（SPA）和外周定量计算机断层扫描（pQCT），用五种不同仪器测量了14名年龄在24.6±1.5岁的年轻健康受试者（10名男性，4名女性）的前臂骨密度。精密度以变异系数百分比（CV%）表示。此外，还计算了长期精密度的标准化CV%（sCV%）和均方根标准差（rmsSD%）。短期精密度的CV%范围为1.04（SPA，远端骨密度）至2.75%（pQCT，小梁骨密度），长期精密度的CV%范围分别为1.49（DXA，QDR 1000，1/3远端骨密度）至4.33%（SPA，超远端）。rmsSD%的结果更高，但与CV%相关性良好。超过2√2 CV%的变化被认为是显著的。在此基础上，预计我们研究中的24.0±5.1%（平均值±标准误）参与者的骨密度会有显著变化，且与两次测量之间的时间延迟无关。使用所有五种仪器在两个部位进行了骨密度测量：分别使用DXA和SPA测量超远端和中段骨密度，使用pQCT测量总体骨密度和小梁骨密度。几乎所有仪器的“仪器间”相关性系数均大于0.5。SPA测量的远端和超远端骨密度以及pQCT测量的小梁骨密度和总体骨密度与DXA测量的超远端骨密度相关性更好。相应地，pQCT和SPA的“仪器内”相关性优于DXA。比较相应部位时，不同DXA方法之间的相关性系数大于0.95。我们得出结论，在年轻健康对照者中，DXA方法、SPA甚至pQCT的低精密度会影响通过测量前臂骨密度监测骨质流失的临床价值。
