Elsevier Pathology

Clinical Pathology: General Principles, Lab Management, Clinical Chemistry

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64) Quality control (QC) material is run at the start of each shift (in this case, for one shift per day) for all assays before testing patient samples. The QC results for several days for one of the assays are plotted on a Levey-Jennings chart shown in the figure. Which one of the following best describes what this Levey-Jennings chart demonstrates?

• Quality Control (QC) procedures are used to detect errors that occur because of test system failure. They are used to monitor the accuracy and precision of laboratory tests.

• For all tests classified as Clinical Laboratory Improvement Amendments (CLIA) non-waived tests, a minimum of two levels of controls must be run on each day that patient testing is performed.

• Levey-Jennings charts show QC results over time and plot how far each point lies from the mean expected value.

• Just by chance, QC values should fall outside 2 standard deviations (SD) from the mean 5% of the time.

• There are many Levey-Jennings rules that are used to flag a QC violation. For example, if a QC value falls 2 SDs beyond the mean, then it would be denoted a 12s violation. If it falls 3 SDs beyond the mean, it is denoted 13s.

• An action plan should be in place to evaluate QC violations.

Centers for Medicare and Medicaid Services. Equivalent Quality Control Procedures Brochure #4. Accessed 15 Jan 2014. https://www.cms.gov/CLIA/downloads/6066bk.pdf

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