Clinical Laboratory Improvement Amendments (CLIA) regulations directing laboratories to verify manufacturer’s performance specifications were created to ensure consistently accurate patient test results. Several accreditation and regulatory agencies require calibration verification at least every six months. Adopting this practice as an ongoing performance check significantly benefits labs and their patients.
In some cases, calibration verification can detect problems with an instrument or assay before quality control (QC) can because it challenges the entire reportable range of the assay. By testing materials with known concentrations as patient specimens, calibration verification streamlines verification of accuracy, precision, and reportable range prior to reporting patient results.
Accuracy is defined as how close a measurement is to the true value. The trueness of a method is typically obtained via a traceable calibration. Calibration verification achieves verification of accuracy or trueness by comparing a lab’s results against the analyte’s typical recovered values throughout the measuring range.
Precision is the measure of how close repeated test results on the same sample are to each other.
Reportable range includes all the values from the lowest to the highest results that can be accurately measured by the assay. Calibration verification verifies the assay’s calibration throughout this entire claimed range ensuring accurate patient results.
Source: How to Verify Performance Specifications
https://www.labflorida.com/internal/COLA/guides/LG13-VerifyPerfSpec2012.pdf
Calibration verification confirms an assay’s full range of coverage and provides critical troubleshooting data when an instrument doesn’t perform as expected. Ongoing calibration verification demonstrates that the range established when the instrument was accepted continues to be maintained.
Calibration verification confirms that the instrument or method performs as expected in your laboratory, with your staff, and for your patients. If the results are unacceptable, labs need to repeat the procedure. If there are still issues, corrective action must be taken and documented.
When to verify:
This includes when a test system is sent to the manufacturer for repairs. Calibration verification must be conducted on the repaired system before resuming patient testing.
This includes when control materials reflect a shift, are outside the lab’s acceptable limits, or when procedures for correcting unacceptable values don’t correct the problem.
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CLIA requirements for calibration verification:
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CLIA does not state the minimum number or replicate numbers allowed. Each lab determines the acceptance criteria, and the medical director defines quality requirements.
Ongoing calibration verification confirms that the instrument’s claimed reportable range is consistently maintained. Calibration validity and assay stability can be checked by running QC materials between verification activities.
Challenging the entire range through calibration verification is invaluable since many methods are calibrated with a 2-point calibrator. Typically, the calibrator’s set point concentrations and the recoveries of two levels of QC account for less than fifty percent (50%) of the claimed reportable range tested in each run. Without calibration verification, the unchallenged concentration region is only challenged by patient samples. This may lead to erroneous patient results, which can have diagnostic consequences.
Calibration verification allows labs to understand where issues are happening. When a system doesn’t perform as expected, calibration verification can be a crucial troubleshooting tool. When samples fail more than once, even after recalibration, only calibration verification can challenge the reportable range and offer insights into the problem.
Determining the acceptability of calibration verification starts with a comparison plot of the observed and theoretical values. The differences are compared using an acceptable total allowable error for the test’s intended use.2 Data must be plotted, reviewed, and documented.
Calibration verification has proven to continuously monitor performance specifications, such as accuracy and precision, while maintaining high-quality standards, even at high test volumes. Understanding and selecting calibration verification materials is an essential aspect of calibration verification.
Materials with known concentrations may be used for calibration verification, including commercially available standards or calibration materials, proficiency testing samples with known results, control materials with known values, or patient specimens with known values.4 Commercial calibration verification kits reduce the need to source patient samples and manufacture admixtures.
To adequately test the system and ensure accurate results throughout the reportable range, CLIA requires testing three levels: one at the high end of the reportable range, one at the low end, and one near the midpoint.
Third-party manufacturers produce five concentration levels to challenge the full reportable range and meet the CLSI EP06 protocol.3 Third-party samples are typically manufactured in human-based matrices to be as patient-like as possible. Dependent, or in kit, control materials, supplied by assay manufacturers are usually manufactured from the same raw materials used in the assay calibrators and quality control samples, making them less effective as independent calibration verification controls.
Independent, third-party products, make it possible to monitor and compare results over time due to batch-to-batch consistency. Third-party manufacturers provide independent and reliable typical values, and peer data is available when purchasing products from most third-party suppliers.
Organizations like CLIA and CAP require laboratories to perform calibration verification to meet licensure requirements in the U.S. and internationally. Yet, a top reason inspectors find clinical labs deficient is incorrect or incomplete calibration verification or not performing it at all.1
Calibration verification should be thought of as more than a semi-annual task to check off a lab’s to-do list. It monitors assay performance over time, maintains quality results, and can detect assay calibration or instrument issues that may be missed by daily QC. Calibration verification offers labs greater confidence in the accuracy of their patients’ results.
Get an in-depth overview of calibration verification, including how and why third-party materials are beneficial to clinical laboratories. Download our white paper, Third-Party Calibration Verification Materials: Pros and Cons, by clicking here or on the button below.
To learn how calibration verification can improve the accuracy of your laboratory’s results, email
CDx-Sales@lgcgroup.com, or call 1-800-377-9684.
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