REGIONAL BONE-MINERAL DENSITY INTERRELATIONSHIPS IN NORMAL AND OSTEOPOROTIC POSTMENOPAUSAL WOMEN

We describe a prospective study in which bone mineral density (BMD) wa s measured in total body and regions, proximal femur, lumbar spine, an d forearm in 84 apparently normal postmenopausal women with normal spi nal radiographs and in 47 women with 1-10 wedged or compressed vertebr ae, There was a history of peripheral fracture in 35 of the 84 control s and 30 of the 47 osteoporotics (p < 0.02) but there was no associati on between vertebral fracture and wrist fracture, At all sites and reg ions, the differences in BMD between the ''normal'' and ''osteoporotic '' women was highly significant and all but ''ribs'' and. ''arms'' rem ained significant after correction for menopausal age, In the whole se t, and in both subgroups, the coefficients of correlation between site s and regions were all highly significant (p < 0.001), Nonetheless, so me sites discriminated better between the two groups than others, Stan dardized odds ratios (OR) for vertebral fracture versus no-fracture we re calculated by logistic regression and expressed as the rise in OR f or each standard deviation (SD) fall in bone density, This ratio was g reatest (3.4) in ''pelvis'' and weakest (1.7) in ''ribs'' but all were statistically significant, Geometric mean regression equations were c alculated for all the 78 possible pairs of sites and regions in the 84 normal subjects and the deviations of the osteoporotic women from the se normal slopes calculated, In most pairs of sites and regions, the v ertebral fracture cases were scattered around the normal group's slope but fell lower down on both axes, The bone deficits in the osteoporot ics compared with young normal women ranged from -14% in ''head'' to - 40% in Ward's triangle and the T-scores ranged from -1.9 in ''ribs'' t o -3.9 in the forearm, Sensitivity ranged from 17% in ''ribs'' to 36.2 % in Ward's triangle, Specificity varied between 88 and 94% and the pe rcent correctly classified ranged from 62.6% in ''ribs'' to 72.5% in W ard's triangle, We conclude that primary postmenopausal osteoporosis a ffects the entire skeleton but that some sites discriminate better bet ween vertebral fracture and nonfracture cases regardless of whether th ey represent cortical or trabecular bone.