How Clinical Labs Ensure Blood Test Accuracy

Clinical lab testing may be uncharted waters for many, but the information these tests provide can help guide many of the decisions a healthcare provider and patient make about one’s health. With 70 percent of medical decisions being based on a lab result, the accuracy of these tests is vital.

For labs in the US creating tests for commercial use, the Food and Drug Administration (FDA) reviews scientific evidence to prove that the test is “accurately able to detect or measure the substance it claims to detect or measure,” and, “the measurement or detection of this substance provides important information about an illness or about health status that assists in the diagnosis, treatment, or monitoring of the patient.”

With more than 13,000,000,000 blood tests performed in more than 250,000 certified clinical laboratories each year in the US alone, ensuring a reliable and accurate test result can set clinical labs apart from their competition. Lab test failures can lead to delayed or incorrect diagnoses as well as unnecessary costs and care.

False Positives and Negatives

The accuracy of the tests relies on a variety of factors, including, but not limited to the test itself, the manufacturer, how common the disease is, the sample collection process (i.e., where and when the test is done), and the patient themselves (hydration level, etc.). Some tests, like mammograms for breast cancer diagnosis, can be incorrect as often as 50 percent of the time, whereas others like a urine test for chlamydia are accurate nearly 100 percent of the time, according to Sasha Guttentag, Ph.D.

Test result accuracy has been a topic of much conversation over the past year, thanks to the worldwide focus on COVID-19 testing. The term “false positive” was mentioned on a nearly daily basis as it relates to the rising cases of COVID-19 infections across the country. A false positive is when a test result is positive when it should actually be negative, or a patient is deemed to have what the test is looking for (in this case, COVID) when they actually do not have it.

The frequency of mistakes with tests correlates to how well the test can correctly identify negative cases. This is referred to as specificity, which is important in clinical testing. If a test has a specificity of 90 percent, that means if 100 people test negative for a disease, 90 of them will be truly negative and 10 will get a false positive result.

On the other end of the spectrum is “false negatives.” This is when a negative result is shown, where it is actually positive. In the testing world, this has to do with sensitivity. A test manufacturer cannot increase the sensitivity of a test without decreasing its specificity and vice versa, according to GoodRx.

Improving Lab Quality

There are a few things that may keep a laboratory director up at night. One of the worst concerns is if an inaccurate test result came from their lab and led a provider to make a poor patient care decision.

False negatives can delay potentially life-saving care and false positives may lead to unnecessary treatment plans. In order to ensure test accuracy, clinical labs must invest in their quality control. The most common reason for a lab to not invest in or upgrade its quality control practices is the cost. While this is understandable, the cost of not investing in quality control can be much higher than biting the bullet and doing so. According to MLO Online, “quality” refers to the standard of one lab’s results compared to others. Generally speaking, every lab can be made more efficient and those that seek a good standard of quality will need to engage in ongoing process evaluation and improvement.

Although clinical labs operate under strict quality regulations that span all phases of the lab testing process, and operational measures are put in place to minimize the chances of errors, mistakes still occur.

Additionally, it’s important to ensure that the phlebotomists are properly trained before they perform the specimen collection, the first step in the process.  According to ScienceDirect, mistakes made prior to samples being tested comprise greater than 70 percent of lab-related errors. When phlebotomists do everything right, it will make the process easier. A blood test result is only as good as the samples that are collected.

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