In a recent article in Annals of Clinical Biochemistry, a group over in the UK did an unusual thing - they audited their IQC (internal quality control) practices. The North Thames Audit and Quality Assurance Group use a questionnaire to assess the IQC practices in 54 laboratories in part of the United Kingdom. Here's the specific citation:
Audit of internal quality control practice and processes in the south-east of England and suggested regional standards. David Housley, Edward Kearney, Emma English, Natalie Smith, Teresa Teal, Janina Mazurkiewicz and Danielle B Freedman. Ann Clin Biochem 2008; 45: 135–139. DOI: 10.1258/acb.2007.007028 (subscription required)
The results are eye-opening. The questionnaire itself was comprehensive and lengthy, so we'll just highlight the most interesting parts.
1. Use of "Westgard Rules." When asked what rules they used for accepting / rejecting IQC (29 responses), 68.9% of the labs used "Westgard" rules of one form or another, while 20.6% used "2s" rules or even tighter limits.
This is an encouraging finding. The use of "2s" limits in laboratories is believed to be more prevalent, certainly in US laboratories.
But there is an important caveat to this survey finding. In a separate question, 22 labs responded that they did use "2s" rules for monitoring. So it is not quite clear if the laboratories that use "2s" monitoring rules are using "Westgard Rules" for acceptance and rejection decisions.
2. Blanket application of one QC rule to all tests. 76% of the laboratories responding used the same IQC rules on all tests, while only one laboratory tailored their IQC efforts based on the needs of individual tests. This is somewhat disappointing. It means that the savings possible from QC optimization and customization (what we term QC Design) are being left on the table for many labs. But this finding is also not terribly surprising, either; laboratories usually lack the skills, tools, and time to commit themselves to QC Design.
3. Is it really out? Finally, the survey seems to have coined an unfortunate term, "non-ideal QC" - which is what occurs when "QC data seemingly showed that an assay had 'failed' to be appropriately controlled.... [ but the run is accepted anyway] .... in order to ensure work is completed." In other words, the control is "out" but the laboratory decides that the run is still "in." 62% of the laboratories said that non-ideal QC is accepted either rarely or never. The other 38% indicated, that it happened occasionally, once per quarter, once per week, 2-3 times a week, and one laboratory indicated that it happened daily.
It would be interesting to know if the same roughly 60% of laboratories using multirule QC are the same roughly 60% that either never or rarely accept non-ideal QC.
Even though this survey is from a specific region in the UK, the findings are relatively close to a private survey conducted by Bio-Rad and Westgard QC a few years ago. In that survey, a slightly higher proportion of laboratories used the "2s" rules alone, and slightly more of them responded to "non-ideal QC" by just repeating the control or taking other action to force the run back "in."
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