Tools, Technologies and Training for Healthcare Laboratories

Electronic QC and the Total Testing Process

POC devices are all the rage. But they don't do normal QC, they do "electronic QC". Just what is "electronic QC"? What does it really measure? And is it ever going to replace the real thing? Dr. Westgard provides a lucid hype-free discussion. (Preview)

September 1998

There's an ongoing interest in alternative QC procedures, especially for point-of-care applications where traditional statistical QC is difficult to implement due to the cost involved, the training required, and the ongoing support needed to update the QC statistics and maintain appropriate QC charts. Manufacturers have been pushing for acceptance of "electronic QC" as an alternative approach and the government and accreditation organizations appear to be getting on board. Laboratory and point-of-care managers need to be clear about the pluses and minuses of this approach.

What is electronic QC?

Electronic QC involves performing an electronic check on an instrument in place of the analysis of a control sample. An electrical signal is substituted for the signal that would normally be generated by a sensor. This is easy to do for certain types of instruments such as those having electrode sensors, where a voltage from a battery (or other stable electrical source) might substitute for the voltage from the sensor. This electrical signal is then measured to see if the right value is obtained on the instrument readout.

The advantages are the simplicity and low cost. It's quick and easy to do and doesn't use up any test cartridges or reagents. Furthermore, the instrument often is programmed to give a Yes or No decision on the acceptability of the value, therefore it takes little training and no understanding of statistics to utilize electronic QC.

Electronic QC isn't new! We've always had photometer checks, filter balance checks, cuvette checks, blank checks, and a variety of electrical voltages that are monitored by the analyst or by the instrument itself. These checks have been part of the overall quality system and used together with traditional statistical QC.

What is the Total Testing Process?

The total testing process includes preanalytic steps (such as specimen acquisition and handling), analytic steps (such as sample manipulation, sample processing, measurement of a signal from the sensor, and instrument readout), and post-analytic steps (recording of test results). A problem or error in any one of these steps can invalidate the results of the whole testing process.

QC provides a way to check whether this testing process is working properly. However, different QC procedures may check different steps of the process. While it is possible to utilize a different QC check for every individual step in the process, it is much more efficient to have a single QC procedure that can check all of the steps in the process. If there's a problem, then it's useful to dissect the process to pinpoint the specific step that's the source of the error.

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