Cut-off values determined for vertebral fracture by peripheral quantitative computed tomography in Japanese women

In spite of the benefits of bone mass measurement by dual-energy X-ray abso rptiometry (DXA), the use of DXA has limitations. It is unable to assess a true bone density, and cannot discriminate between the trabecular and corti cal bone compartments. Ultradistal radius bone density was measured using p eripheral quantitative computed tomography (pQCT) to determine reference va lues for total bone density (BD), trabecular bone density (TBD), polar stre ngth strain index (pSSI), total bone mineral content (BC), trabecular bone mineral content (TBC), cortical bone density (CBD), cortical bone mineral c ontent (CBC) and polar cross-sectional moment of inertia (pCSMI) in the Jap anese female population, and to ascertain the cutoff values of the measured indicators that could most efficiently discriminate osteoporotic subjects with vertebral fractures. A total of 5266 healthy Japanese women aged 20-89 years were included in this study to determine Japanese reference values. Additionally, 621 who had undergone radiographic examination of the thoraci c and lumbar spine at the time of pQCT measurement were selected to determi ne the cut-off values of BID, TBD, pSS1 and other indicators for vertebral fractures. All the healthy subjects were divided into 5 year age groups. Th e BD showed nonsignificant changes from the 20-24 year age group to the 45- 49 year age group, and fell significantly thereafter. The TBD maintained a plateau until the 40-44 year group, which corresponds to the young adult me an (YAM) values of the lumbar spine, femoral neck and radius BMDs measured using DXA. The TBD decreased significantly thereafter. The pSSI did not cha nge significantly from the 20-24 year age group to the 45-49 year age group , and decreased slightly in the 50-54 year age group and markedly after 55- 59 years. The cutoff values for the discrimination of vertebral fractures w ere obtained by the calculation of sensitivities, specificities and the are a under the curves obtained using age-adjusted receiver operating character istics (ROC) analysis. Odds ratios and 95% confidence limits (CL) were calc ulated using age-adjusted logistic analysis. The cut-off values for vertebr al fractures, the area under the ROC curves (AUC) and odds ratios were 270. 1 mg/cm(3) (-2.2 SD, 66.6% of YAM), 0.689 +/- 0.025, 2.10 (1.63, 2.70) for BD, 104.8 mg/cm(3) (-2.2 SD, 53.5% of YAM), 0.699 +/- 0.023, 2.17 (1.69, 2. 77) for TBD and 192.8 mm(3) ( -1.9 SD, 59.8% of YAM), 0.631 +/- 0.028, 1.72 (1.34, 2.21) for pSSI, respectively. These findings suggest that ultradist al radius BMD measured using pQCT can be used to discriminate women with ve rtebral fractures.