Importance of precision in bone density measurements

Bone densitometry, regardless of the specific technique, is not perfectly r eproducible even when consistently performed in exact accordance with the m anufacturer's recommendations. Precision must be quantified at each densito metry facility in precision studies of the various skeletal sites used for monitoring. The precision, as the root-mean-square standard deviation or ro ot-mean-square coefficient of variation, is then used to determine the chan ge in bone density that constitutes the least significant change and the mi nimum interval between follow-up measurements. Until precision studies are performed, the least significant change cannot be determined for any level of statistical confidence, making the interpretation of serial studies impo ssible.