Comments on the hypotheses underlying fracture risk assessment in osteoporosis as proposed by the World Health Organization

It was shown in a recent multivariate analysis of lumbar vertebral (L1-L3) CT scans of 171 women without fractures and 57 fractures somewhere in their skeletons, that regional assessment of the spinal mineral distribution can result in the discrimination of the above patient groups with an accuracy of about 90%. This level of discrimination was possible even in those cases with bone densities below the fracture threshold, where the overlap of pat ients with and without fractures is the greatest and clinically the most si gnificant. In this region this new analytical technique could also identify a subgroup of patients who not yet had a fracture, but for whom all three lumbar vertebrae were classified as osteoporotic. From these results it fol lows that the osteoporosis model proposed by the World Health Organization (WHO), which assumes that fragility depends only on a single mean value of bone mineral density (BMD) for a patient, is overly simplistic and requires upgrading to include indices representing the distribution of bone mineral .