El Maghraoui A, Do Santos Zounon A A, Jroundi I, Nouijai A, Ghazi M, Achemlal L, Bezza A, Tazi M A, Abouqual R
Rheumatology and Physical Rehabilitation Department, Military Hospital Mohammed V, Rabat, Morocco.
Osteoporos Int. 2005 Dec;16(12):1742-8. doi: 10.1007/s00198-005-1916-2. Epub 2005 Jun 4.
Bone mineral density (BMD) measurements are frequently performed repeatedly for each patient. Subsequent BMD measurements allow reproducibility to be assessed. Previous studies have suggested that reproducibility may be influenced by age and clinical status. The purpose of the study was to examine the reproducibility of BMD by dual energy X-ray absorptiometry (DXA) and to investigate the practical value of different measures of reproducibility in three distinct groups of subjects: healthy young volunteers, postmenopausal women and patients with chronic rheumatic diseases. Two hundred twenty-two subjects underwent two subsequent BMD measurements of the spine and hip. There were 60 young healthy subjects, 102 postmenopausal women and 60 patients with chronic rheumatic diseases (33 rheumatoid arthritis, 10 ankylosing spondylitis and 10 other systemic diseases). Forty-five patients (75%) among the third group were receiving corticosteroids. Reproducibility was expressed as the smallest detectable difference (SDD), coefficient of variation (CV), least significant change (LSC) and intraclass correlation coefficient (ICC). Sources of variation were investigated by linear regression analysis. The median interval between measurements was 0 days (range 0-7). The mean difference (SD) between the measurements (g/cm2) was -0.0001 (+/-0.003) and -0.0004 (+/-0.002) at L1-L4 and the total hip, respectively. At L1-L4 and the total hip, SDD (g/cm2) was +/-0.04 and +/-0.02, CV (%) was 2.02 and 1.29, and LSC (%) 5.60 and 3.56, respectively. The ICC at the spine and hip was 0.99 and 0.99, respectively. Only a minimal difference existed between the groups. Reproducibility in the three groups studied was good. In a repeated DXA scan, a BMD change, the least significant change (LSC) or the SDD should be regarded as significant. Use of the SDD is preferable to use of the CV and LSC because of its independence from BMD and its expression in absolute units. Expressed as SDD, a BMD change of at least +/-0.04 g/cm2 at L1-L4 and +/-0.02 g/cm2 at the total hip should be considered significant. This reproducibility seems independent from age and clinical status and improved in the hips by measuring the dual femur.
骨密度（BMD）测量通常会对每位患者进行多次。后续的BMD测量可用于评估重复性。先前的研究表明，重复性可能受年龄和临床状况的影响。本研究的目的是通过双能X线吸收法（DXA）检测BMD的重复性，并调查在三组不同受试者中不同重复性测量方法的实用价值：健康年轻志愿者、绝经后女性和慢性风湿性疾病患者。222名受试者先后接受了两次脊柱和髋部的BMD测量。其中有60名年轻健康受试者、102名绝经后女性和60名慢性风湿性疾病患者（33例类风湿性关节炎、10例强直性脊柱炎和10例其他全身性疾病）。第三组中有45名患者（75%）正在接受皮质类固醇治疗。重复性用最小可检测差异（SDD）、变异系数（CV）、最小显著变化（LSC）和组内相关系数（ICC）表示。通过线性回归分析研究变异来源。测量之间的中位间隔为0天（范围0 - 7天）。L1 - L4和全髋部测量之间的平均差异（标准差）分别为-0.0001（±0.003）和-0.0004（±0.002）。在L1 - L4和全髋部，SDD（g/cm²）分别为±0.04和±0.02，CV（%）分别为2.02和1.29，LSC（%）分别为5.60和3.56。脊柱和髋部的ICC分别为0.99和0.99。各组之间仅存在极小差异。所研究的三组的重复性良好。在重复的DXA扫描中，如果BMD变化达到最小显著变化（LSC）或最小可检测差异（SDD），则应视为有意义。由于SDD与BMD无关且以绝对单位表示，因此使用SDD比使用CV和LSC更可取。以SDD表示，L1 - L4处BMD变化至少达到±0.04 g/cm²且全髋部达到±0.02 g/cm²时应视为有意义。这种重复性似乎与年龄和临床状况无关，并且通过测量双侧股骨，髋部的重复性有所提高。
