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In his recent webinar,1 Sten Westgard, Director of Client Services and Technology at Westgard QC, an independent consulting and training company specializing in clinical laboratory quality control (QC), gave insights into how laboratories can evaluate their performance ahead of the pending CLIA changes. He also presented results of benchmarking performance of the “big five” diagnostic manufacturers: Abbott, Beckman Coulter, Roche, Siemens, and Sysmex.
What’s CLIA?
The United States Congress first passed CLIA, the Clinical Laboratory Improvement Amendments, in 1988, “to establish quality standards, strengthen Federal oversight of clinical laboratories, and ensure the accuracy and reliability of patient test results.”2
CLIA are federal standards applicable to any laboratory in the United States that performs in-vitro diagnostic tests on human specimens for assessing health or diagnosing, preventing, or treating disease3 to ensure that patients receive accurate, reliable, and timely results, no matter where their test is performed.2 And CLIA rules, while not required outside the US, international laboratories may also apply for CLIA certification.4
In 2024, CLIA requirements for proficiency testing will be implemented. The 2024 guidelines incorporate 23 new tests and update the criteria for dozens more across chemistry, immunoassay, and hematology,5 marking the biggest changes in United States regulations since 1992. Some updates additions of previously unregulated tests (e.g., hemoglobin A1c testing), and some updates are due to improvements in accuracy and precision of many tests.6
What’s changing?
CLIA 2024 introduces new quality requirements for proficiency testing, with hard numbers and tighter goals for many analytes. The changes will affect the QC practices and efficiency of laboratories and will vary depending on how the analyte goal was previously measured and what instruments the laboratory is using.
Some of the newly regulated analytes were never regulated, some have shrinking ranges (up to 40%), and still others were previously relative numbers. For example, hemoglobin A1c (HbA1C) was previously not regulated, but now has a target value ± 8%. Human chorionic gonadotropin (β-hCG) testing previously required the target value ± 3 standard deviations (SD),7 but these SD-based goals rely on individual laboratory performance, making them non-transferrable between labs. The new goal will require the target value ± 18%—a hard number. And for cortisol, the target range is shrinking from 25% to 20%—a 40% reduction.1,8
Similarly, the 2024 CLIA guideline changes for hematology analyzers include significant tightening of goals. One Westgard survey of almost 60 labs in the United Kingdom showed that >70% of labs set their target ranges to 3 standard deviations or more, >40% were over 4 standard deviations, and it was not unusual to have values over 5 standard deviations! For 2024, the total allowable error goals for hematocrit (HCT), red blood cell (RBC), and total white blood cell (WBC) counts are all dropping by 33.3%, while that for hemoglobin (Hgb) is dropping 42.8%.1
Good Company
For CLIA, a test system usually includes both the analyzer and the assay, labs must verify the performance of each assay on each of their instruments. Tighter CLIA goals mean that QC efforts will need to increase for some tests and for some instruments.1
The analytical sigma metric is a way to measure the performance of an assay against a quality requirement. Using sigma metrics, current assays and analyzers can be benchmarked and compared with the 2024 CLIA requirements to understand what changes labs may need to be incorporated to be in compliance come July. The higher the sigma value, the better the chance for compliance.
Analyzers, of course, are not created equally. Different instruments and assays vary in their sigma performances. Of the immunoassay analyzers evaluated by Westgard, the DxI 9000 Immunoassay Analyzer† showed the highest number of six sigma assays and the lowest number of assays below three sigma.
