Medical treatment guidelines, such as the American College of Occupational and Environmental Medicine and the Work Loss Data Institute’s Official Disability Guidelines, recommend urine drug testing for injured workers prescribed opioids. And yet, studies show that few physicians actually prescribe them.

There’s been quite a bit of controversy about UDT of late. There are concerns about whether it is overused, underused, effective or too expensive. Along with the controversy there is, of course, much confusion.

Having spent a couple of years writing and overseeing a biweekly newsletter on workplace substance abuse in the early 2000s, and now having a client that performs drug testing, I thought I’d share my admittedly limited knowledge of the subject and maybe clear up at least some of the confusion about UDT; its history and changes, and why I believe it is, if used appropriately, a highly useful tool in identifying candidates for and preventing abuse/misuse/overdose for injured workers prescribed opioids.

To be clear, there is some overuse of UDT and, even more so, inappropriate UDT.

The fact is, all urine drug tests are not created equally. There is forensic UDT and clinical UDT. They have different purposes and should not be used interchangeably.

A bit of history is in order.

Much of UDT today is done simply to detect the presence or absence of illegal drugs in a person’s system. Job seekers, workers involved in workplace accidents, and athletes are among those typically subjected to simple drug tests. The type of testing in such cases is generally based on the Mandatory Guidelines for Federal Workplace Drug Testing Programs, developed by the U.S. Department of Health and Human Services.

This "forensic," or point-of-care drug testing is based on the assumption that the person will test negative for illicit substances. The consequences for those who test positive on such tests can be severe, ranging from loss of a job, to loss of custody of a child, to incarceration. Therefore, any positive test result is typically sent for confirmatory testing to prove the results.

The type of test used for forensic screening is often immunoassay and provides a qualitative determination as to the presence or absence of drugs in a sample, essentially a "yay" or "nay."

These tests are fine for the purpose for which they were created, to weed out those individuals who have very recently ingested an illegal substance. They are generally cheap, fast and readily available. However, they are not designed for, nor are they very effective for clinical applications.

There is a significant difference between the standards and needs of forensic tests to detect illicit drug use and clinical tests to monitor adherence to a treatment regimen.

The problem with using forensic drug testing in a clinical application is that it is severely limiting. Forensic tests typically detect mostly medication classes and only a few parent drugs, rather than specific metabolites or multiple drugs in the same class. There are often false negative results due to the high cutoff levels that prevent the tests from detecting low levels of medications. They may also fail to detect opioid-like medications, such as tramadol and tapentadol, as well as synthetic opioids, such as fentanyl and methadone.

False positive results also happen since certain immunoassays are subject to cross-reactivity from other medications and over-the-counter drugs and may produce inaccurate results. And, there is a limited specificity for certain medications within a class.

Clinical UDT, on the other hand, expands the list of drugs detected. This is significant, as virtually all injured workers on opioid therapy would be expected to test positive on a screening. The clinical test could detect which opioid was in the injured worker’s system.

The current gold standard of clinical UDTs is liquid chromatography/tandem MS. These tests are far more accurate than forensic tests, can identify parent medication and metabolites and identify specific medications, rather than just drug classes.   

In a recent comparison of point-of-care vs. clinical tests, 27% were incorrectly identified as positive for oxycodone/oxymorphone. The low sensitivity of the tests can mistakenly identify codeine, morphine or hydrocodone as the same drugs.

Similarly, they missed the identification of benzodiazepines in 39% of the patients.

In terms of determining adherence to a drug regimen, immunoassay is a waste of time – and money. It may be positive for opiates – which, if the person has been prescribed opiates, would be expected. So it doesn’t tell you anything you didn’t already know. But it likely won’t tell you what opiate the person is taking. Similarly, if there is a false negative, then what? Do you assume the person is NOT taking the prescribed meds? Could just be the test is not sensitive enough!

In addition to the confusion about the types of UDT, part of the recent controversy may also stem from the fact that a handful of unscrupulous physicians are apparently performing the simpler, point of care tests in their offices or labs they own. The initial test, analysis and confirmatory test (since virtually all tests on injured workers receiving opioid therapy would be positive), can result in three separate bills to the payer. There are reports of some addiction treatment centers making more money testing patients than treating them.

The other question about UDT concerns how often they should be performed on a given injured worker. The frequency of UDT is supposed to be determined by medical necessity, as decided by the medical provider. There is no one-size-fits-all answer, as each injured worker is different.

Experts say the frequency of the tests should be determined by risk factors. An injured worker who is depressed, male, a smoker and has a history himself and/or family history of substance abuse would likely warrant more frequent testing than someone with no known risk factors who is fully cooperating with those handling his claims and eager to or already performing light-duty work. It’s a tough call and, so far, it is not an exact science. The best advice for practitioners is to look for thorough documentation from providers, communicate with all parties – especially the injured worker, and become informed on the type and frequency of UDT performed for each injured worker.