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What Is The Difference Between POCT, Lab and Express-To-Lab?

Having trouble sorting through the complexities of different drug testing methods? This post will help you weigh the benefits and disadvantages of each so you can make an informed choice on which method is best for your workplace.

Laboratory Testing

A lab-based drug test has two stages. The first is an initial screen test completed at an accredited laboratory using immunoassay technology, a type of biochemical test that has an accuracy rate of over 99%. If the screen test is non-negative, a GC/MS confirmation test follows. The GC/MS technology is the gold standard, and is highly technical and accurate scientific analytical equipment that precisely identifies different drugs and their quantities.

Express Test or Point of Care/Collection Test (POCT)

An express test or POCT is a portable test that is done in the field, instead of at the lab. It gives employers a quick snapshot that may reflect the actual result. The POCT also uses immunoassay technology but its accuracy rate is slightly lower than lab-based immunoassay testing, depending on the brand of kit used and the drugs tested for. Only non-negative POCT results are sent to the lab for GC/MS confirmation testing.

Express-To-Lab Testing

An express-to-lab test is a POCT that is sent on for a lab-based immunoassay screen test regardless of whether the POCT is negative or non-negative. If the lab-based screen test is non-negative, a GC/MS confirmation test will follow. Sending every sample on for a lab-based screen test whether it is negative or non-negative provides an added level of assurance, since POCTs are not as accurate as lab-based tests.

Policy Considerations

If you do express (POCT) testing or express-to-lab testing, you need to decide how to manage your worker while you wait 8-72 hours (depending on whether it is negative or positive) for the results of the confirmation test. Ask yourself: should your employee start or continue working in a safety-sensitive position until the confirmation test result is verified? Or will the employee be removed in the meantime?  For express-to-lab testing in particular, if the POCT is negative but the lab-based screen is non-negative and an incident occurs in the meantime, your company could be liable. You may need legal advice to help determine how much risk you are willing to take on.

Check out our summary chart for a quick comparison of these testing methods: