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As a wellness professional, I often receive questions from clients about why their employees' biometric screening results differ from what they received from their doctor or from the previous screening vendor. While there are a few factors that can create a variance, I wanted to do a little more digging—after all, the popularity of biometric screenings is continuing to skyrocket, and I think it's always better to have a clear understanding of what our clients are investing in.

But first, what's a biometric screening—and why are they so popular? The rise of workplace wellness programs has also sparked an increase in on-site physicals to provide a better benchmark for employers when it comes to investing in their workforce's health. A basic screening measures physical characteristic such as height, weight, body mass index, blood pressure and aerobic fitness.

According to the Willis 2014 Health & Productivity Survey, 74 percent of US employers include a biometric screening as part of their workplace wellness programs. If you're currently providing screenings, or considering it, here's what you need to know about the accuracy of the process, and how labs analyze biometric screenings:

1) No two labs will have identical test results

Lab variance occurs when two or more labs receive the same blood sample, but end up with different results. In this event, technically each of the test results are correct. How is that possible? Well, according to the Clinical Laboratory Improvement Amendments (CLIA), laboratories are allowed a +/- 20 percent variance between other labs (which we'll dive more into next).

Lab variance happens because the testing methods differ from lab to lab—each lab has different preliminary testing controls, different machines and obviously, different technicians working. When just these three variables are introduced into the testing process, the results are subject to minor changes. This is why your physician will send blood samples to the same laboratory, instead of multiple labs—the percentages for accuracy and precision aren't the same for every lab.

How does this impact your employees' screenings? If you plan on switching screening vendors, inform your employees about it upfront. Otherwise, they may be blindsided by a potential swing in their health numbers without understanding why.

2) Labs are allowed a 20 percent variance

The below image illustrates how variance works using real data from our lab partners over at Bayshore Clinical Laboratories.

Nearly 5,000 labs completed a required audit on their equipment and testing method, which was then plotted as a whole to determine the mean. The goal for any lab is to be closest to the average, which determines the most accurate result. For total cholesterol, Bayshore was nearly spot on at 158.9, where the mean was 163.

3) Labs go through rigorous testing and quality control audits

While results can vary, labs are still held to strict standards to ensure this variance doesn't impact your employee's healthcare provisions. According to Ken Jaglinski, laboratory director at Bayshore, labs base their work on two things: precision and accuracy. Precision means that across multiple tests, they must hit the same result consistently. Accuracy means that if there is an expected result, they must hit that result as closely as possible (like

getting a bullseye, or as close to it as possible multiple times).

How do labs ensure precision and accuracy? First, they run preliminary tests on every machine to make sure they are current. Next, each test sample is monitored through test validation and plotted on a quality control chart to compare to other labs testing the same characteristics. The below target represents an actual plot of Bayshore's results for a single test to preserve their own accuracy. Lastly, each lab participates in state-regulated testing to ensure as much consistency as possible.

What does this mean for you? When picking labs to work with, ask to see their latest validation test, so you can compare their results to other labs.

4) Results from portal analyzers are not usable for clinical diagnosis

If you want your employees to use their test results from your company's biometric screening event, then make sure your screening vendor is sending the blood samples to a CLIA certified laboratory.

The problem with CLIA-waived or non-certified testing is that the results aren't diagnosable, so your employees' doctors may end up re-ordering the same lab tests for them. Dry blood spot cards are the best of both worlds: They use finger stick testing (the least invasive method) while still being analyzed in a lab (also the most accurate).

Have any other questions about how biometrics screenings work for workplace wellness programs? Get in touch at

Header photo: Shutterstock