Clinical practice guidelines: when the tool becomes the rule.

This work provides a critical examination of the use of clinical practice guidelines to measure individual performance. The problems inherent in using a measure of central tendency derived from a distribution of individual performances are addressed, as is the translation of the collectively determined guidelines into a measurement instrument. It is suggested that every process on the distribution of processes used to determine the guideline must be considered equally legitimate representations of the process in question. It is further suggested that to accept as a standard of quality, a particular process simply because there is a minimum of variation between providers, is to ignore the importance of the linkage between process and outcome. The importance of an independent measure of quality based on outcomes is further emphasized by highlighting the tautological nature of analyses that include an input measure, such as nursing hours, in both the dependent variable and the list of independent variables. It is recommended that individual performance be evaluated within the tolerances of the distribution from which they were derived and not be held to some measure of central tendency of that distribution. The alternative is to use the measure of central tendency with plus or minus limits such as one, or more, standard deviations.