The Importance of Precision in Densitometry
The concept of precision was introduced in Chapter 3. Current bone densitometry technology cannot perfectly reproduce BMD results from test to test, even when there has been no real change in the patients BMD. If there is any additional error introduced by the failure of the technician to perfectly reposition and correctly analyze the results, the precision of the test will be adversely affected even more. This being the case, how can a physician determine if any measured change in BMD is a real, biologic change, and not simply the error that is inherent in the technique, or the error introduced by the technician? The first step is to determine the short-term precision for each type of scan that is performed at the densitometry facility. Short-term precision implies that the precision has been determined using repeat studies performed within the space of a week to no more than a month. In a medium-term precision study, the scans have been acquired over a period of time that spans 1 to 6 months. A long-term precision study implies data acquisition that spans more than 6 months.
KeywordsMeasured Change Statistical Confidence Bone Densitometry Real Change Precision Study
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