How many mistakes, how to find them

The topic of quality control often evokes prolific discussion among those whose business is its administration. Reliable methods for identifying mistakes must be developed in both the manufacture and use of test devices. Unit test devices are uncomplicated to run and provide quick results in a world where speed and simplicity are paramount, yet their very nature as individual assay units introduces questions about the relevance of conventional quality control procedures. Hybritech's ICON(R) QSR(R) CKMB assay is a unit test device that requires daily monitoring according to CLIA'88 regulations. The challenge is to ensure that quality-control testing is value-added, assuring clinicians valid patient sample results although controls are run in a separate ''assay.'' We find that conventional quality-control procedures are indeed valid; however, the fundamental difference of unit test devices must be recognized and accounted for by understanding the capability of the assay in each laboratory.