Cut off values of bone mineral density defining postmenopausal women with bone fractures.

OBJECTIVES To define cut off values of bone mineral density (BMD), measured at different forearm sites by single photon absorptiometry, that discriminated postmenopausal women who have had fractures from those who have not, in order to provide an index of fracture risk for screening purposes. METHODS BMD values were measured at distal third radius (DTR) and ultradistal radius (UDR) sites in two groups of postmenopausal women. Group 1 (n = 398) had not suffered fractures, and group 2 (n = 354) had appendicular fractures. Results were evaluated using receiver operating characteristic (ROC) curves. RESULTS BMD values were significantly greater (p < 0.001) at both sites in group 1. Weight was lower in group 2 than in group 1 (p < 0.001). The BMD cut off value was 0.596 g/cm2 at DTR (sensitivity 63%, specificity 72%), and 0.310 g/cm2 at UDR (sensitivity 80%, specificity 80%). Values of area under ROC curves estimated for UDR were greater than for those DTR (p < 0.001). CONCLUSION For screening purposes the BMD cut off value of 0.310 g/cm2 at the UDR may be useful in identifying women at high risk of fracture in an unselected postmenopausal population. BMD measured at UDR appeared to have a better predictive value than that at DTR.