At CLEAR we believe transparency is crucial. Since the announcement of the European strain of Chlamydia back in November, we have had lots of questions about how we identified the strain and what laboratories should do in case their results conflict with another laboratory.
This post outlines the steps most laboratories take to verify the accuracy of their results as well as how we identified the Chlamydia strain among our patient population.
What is a correlation study?
A correlation study is a comparison of two or more laboratory tests or instruments against each other. It is used to validate the accuracy of a test and/or platform. This type of study is a standard practice among all laboratories.
Why is it important?
In science, variables are common. No matter the methods being used or how long a laboratory has been in business, one cannot assume it is using “the best method” or that its findings cannot be contested. By examining differing methods or scenarios, we can more accurately define the true performance of a test (or methodology, in lab speak). The best way to ensure accuracy is to eliminate any potential issues that may be part of the process and to focus on the science behind how it’s done.
How is it useful?
In situations where there are conflicting results, a correlation study can help isolate probable causes and allows the laboratory to determine the nature of the problem, and in some cases whether there is a problem at all. Correlation studies are commonly done “blind”, in other words, without each party knowing the expected outcome. This allows the findings to be completely impartial.
How is it performed?
Step 1: Correlation studies begin internally by identifying any probable causes of variance within the lab itself. Items to evaluate include a review of all policies and procedures, staff retraining, consideration of environmental factors, etc.
Step 2: To send specimens out to an impartial laboratory that will look at only the science and not be biased in any way. This is accomplished by the “blind” element of the study - the other laboratory should have no reference to the expected results - positive, negative, non-reactive, etc. This allows them to focus only on the scientific portion and deliver accurate clinical results.
Step 3: Depending on the outcome of Step 2, this third step may involve confirmation by highly-sensitive testing, to verify the findings on a molecular level. This serves to disciple any potential notion of result inaccuracy by isolating specific compounds that can confirm the initial lab findings.
Do all labs do this?
Most do. Recently, CLEAR was made aware of discrepant results on Ct/Ng and followed the steps outlined above. By doing so, we were able to identify that the discrepancies were not discrepancies at all, but instead, true positive results caused by a new variant of Ct/Ng that is not detectable using normal lab methods. The findings of this recent correlation study are available below.
What happens if a lab does not perform correlation studies?
Molecular testing is not a black-and-white science. So while laboratories are not required to do correlation studies when questions arise about the accuracy of their test results, it is considered best practice to do so.
What does this mean to me?
Like most other sciences, laboratory science is generally accurate within a very small margin of error. No matter the protocol a laboratory is using, the accuracy of results is only as good as the policies and procedures governing it. It is essential to ensure that your laboratory provider is relentless in the pursuit of excellence, especially as it relates to the impact on your health and safety.
By demanding transparency in how your laboratory conducts its testing you will be able to ensure that your results can be trusted.
How CLEAR identified the European Variant of Chlamydia
In November of 2022, CLEAR was made aware that some performers were receiving Chlamydia results that conflicted with other laboratory testing facilities. Some performers were testing positive for Chlamydia at CLEAR and then negative at another laboratory, in some cases the very same day. To rule out any issues with our processes, we immediately engaged two third-party labs to conduct a correlation study of multiple samples to determine whether our findings were accurate.
How we solved it?
Day 1: Full audit of all staff training and sample processing workflows.
Day 2: Retesting of discordant samples as well as randomized in-house blind sample testing.
Day 3: Sent discordant samples for blind testing at two independent laboratories to verify our findings.
Day 4: Received results from third-party labs that agreed with 100% certainty with CLEAR’s findings.
Day 5: Sent out all samples involved for NGS (Next Generation Sequencing) testing, to further confirm the diagnosis.
Day 12: NGS results were received and confirmed the original results, also indicating that the discrepancy was caused by the European Chlamydia variant (C1514T) found in the samples.
In summary, CLEAR’s results were conflicting with other laboratories, so we conducted a correlation study to determine whether we were reporting results accurately. In the process of doing so, we identified that an unknown strain of Chlamydia was causing the discrepancy. The strain could not have been identified by other laboratories since CLEAR was using an updated assay (set of equipment reagents) that was able to identify the strain.
Had we not conducted an independent, unbiased study to challenge our findings, patients would continue to question their results. More importantly, it would have allowed performers to continue to work assuming they were negative and further disseminating the bacteria to other performers.
The findings of the correlation study are available below for review.
How to read the report
The columns in yellow shows the results reported by CLEAR, while the first three green columns show the comparative results reported by the third-party lab on the blind study conducted. The far-right green column shows the results of the additional NGS (Next Generation Sequencing) tests reported to confirm the original findings.
Looking at each sample identifier - columns "WL" and "Sample ID" - you will notice that the results reported by CLEAR were confirmed first by the initial retesting (green columns "CT Results" & "GC Results") and additionally by the "23S CT Sequencing Results".