Setting quality goals for laboratory tests

Abstract

The ideal situation with regard to quality assurance in clinical pathology would be that quality goals in numerical format were available for all the practicability and reliability characteristics of laboratory tests, particularly the latter. Many strategies have been used for the setting of quality goals for the most important reliability characteristics, namely, imprecision and bias. These have included fractions of the reference interval, opinions of clinicians, the state of the art, views of expert individuals and groups, the influence of analytical error on clinical utility and biological variation. All of these have advantages and disadvantages. In spite of some interesting recent proposals, quality goals based on biological variation appear to be the best currently available and seem to have led to a consensus among Europeans that, in simple terms: 1. desirable maximum imprecision < one-half the within-subject biological variation, 2. desirable maximum bias < one-quarter the group [within- plus between subject] variation, and 3. maximum difference between methods < one-third the within-subject biological variation. There appears a need for further work in setting quality goals for laboratories which deal with samples from animals; international collaboration has proved productive in human clinical biochemistry and may be worthy of emulation.