CHOOSING BETWEEN PREDICTORS OF FRACTURES

The identification of those at highest risk of osteoporotic fractures is a clinical goal that requires appropriate statistical comparisons o f potential predictors of fractures. This article provides a formal ap proach for comparing individual predictors (e.g., bone mass at one sit e vs bone mass at another), or sets of predictors (e.g., bone mass vs other risk factors), and contrasts newer methods, such as bootstrappin g, to receiver-operating-characteristics (ROC) curves, which have been previously used. The advantages of the bootstrapping approach are ill ustrated using time-to-fracture data from a published study demonstrat ing the use of baseline bone mass measurements in the prediction of fr actures in 521 subjects with variable lengths of follow-up, extending to 12.5 years, Bone mineral density (BMD) was shown to be significantl y better than bone mineral content (BMC) in predicting fractures in fr ee-living subjects, but not in retirement-community subjects. Bone min eral apparent density (BMAD) was also compared with BMC and BMD and sh own not to improve fracture prediction in these subjects.