A crossover comparison of four peripheral bone-site measurements to identify central osteopenia and osteoporosis in women

The objective of this study was to assess the ability of four peripheral bone measurement sites to predict low bone mineral density of the lumbar spine, femoral neck, and total hip as defined by the WHO classification, and to evaluate their role as a screening procedure for central dual-energy X-ray absorptiometry (DXA). One thousand three hundred white women patients aged 58.3±13.9 years were enrolled. Correlations between the peripheral and central sites were moderate, varying between 0.51 and 0.67. In receiver-operating characteristic (ROC) analysis, the areas under the curve for the peripheral sites revealed a few small, but significant, differences between sites. The optimal cut-point was derived from the ROC data for each site to assess its value as a screening parameter. These proved to be unsatisfactory, because the average number of false positives and false negatives were 18% and 24%, respectively. A proposal is made which entails two cut-points, one for an acceptable percentage of false negatives and the other for an acceptable number of false positives. Patients with t-scores between these cut-points would be referred for central DXA for classification. The result is a substantial decrease in the number of false negatives, i.e., patients who would be candidates for treatment. The contentious issue is what proportion of supplemental DXAs is considered logistically and economically acceptable for any of the peripheral site measurements to be useful.