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The Frequency of Quality Control in Clinical Laboratory

What You Need to Know about the Frequency of Quality Control in Clinical Laboratory

Errors in clinical testing are rare, but they do happen.

Considering that 60 to 70% of all medical decisions are made on the basis of laboratory tests, even the minor 0.012-0.6% reported frequency of laboratory errors is not acceptable.

That’s exactly why a clinical laboratory should regularly conduct Quality Control (QC) testing.

At Lab Me, we always use CAP-accredited labs. This gives us (and you) the peace of mind that our test results are accurate and 100% reliable.

As a patient, you don’t need to know the nitty-gritty of laboratory best practices, but you may still have some questions about QC testing, such as….

What is Quality Control testing? How often should a lab conduct them? So, let’s dig deeper into the subject.

What is Quality Control?

Quality Control is exactly what it sounds like. It is a way of controlling the quality of the methods and tools that a clinical laboratory uses to produce their patient results.

To that end, labs usually run a Quality Control (QC) test every morning before they start performing their patient tests.

If the QC result shows no discrepancy, it means the lab instruments are performing according to their predefined specifications.

Simply put, a QC test is a way to validate the accuracy of patient results.

Differences between a patient test and a QC test

One notable difference between a patient test and a QC test is this.

A patient test is performed on the patient’s specimen, such as blood and urine samples.

In comparison, a QC test is performed on a patient-like product, also known as QC sample.

While QC samples are different from patient specimens, the former is often made from human blood or urine and closely resembles the features of patient specimens in terms of turbidity, viscosity, color, and composition.

How often should a lab conduct QC testing?

Running one test a day is a de facto standard, but some labs may need to run QC tests more often.

Ideally, labs should consider the below factors when determining the right frequency of Quality Control in their situation.

1) Stability – Not all quality materials are created equal. That’s why some QC tests are more stable than the others. If the quality material is NOT stable enough for a 24-hour analytical run, then labs should run tests more frequently.

2) Patient risk – The whole idea of running a QC test is to help patients get an accurate and timely diagnosis. With that in mind, labs should increase the frequency of QC testing in cases where the repercussions of a wrong or delayed result could be devastating.

3) Number of patient tests between QC evaluations – Let’s take an example to understand this. Both “Lab X” and “Lab Y” perform one QC test per day in the morning.

But Lab X runs 30 patients, while Lab Y performs 500 tests daily.

So, for both labs, any QC failure halfway through the day will go undetected until the next morning.

But, since Lab Y runs 500 tests daily, they now have to deal with a greater number of faulty patent results (around 250) than Lab X.

So, a better solution for this situation would be to run patient tests in batches, for instance after every 150 or 200 patient tests.

Hopefully, now you have a clear idea of how labs determine the right frequency of QC testing for them. With that mind, make sure you get your tests done from CAP-accredited labs.

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