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 (UDT) for monitoring injured workers who are prescribed opioids. Yet studies show that few physicians actually order the tests.
There are a variety of concerns about UDT, including its potential overuse, underuse, effectiveness and cost. The guidelines are fairly nonspecific in terms of the frequency and type of testing that are most appropriate for injured workers. The fact is, all UDTs are not created equal and should not be used interchangeably.
Immunoassay tests, for example, are preferred when simply trying to detect the presence or absence of illegal drugs in a person’s system. More sophisticated tests, such as liquid chromatography, may be more suitable for clinical applications. They are far more accurate than immunoassay tests, can identify parent medication and metabolites and can identify specific medications, rather than just drug classes.
The differences in the types of drug testing have important ramifications for patients. For example, inappropriate or insufficient testing can put injured workers at risk for drug overdoses.
“The type of testing clinicians use should depend on the purpose,” said Steve Passik, vice president of Clinical Research and Advocacy for San Diego-based Millennium Health. “The immunoassay test comes from a forensic application and vocational application. In those settings, only the most egregious offenders are meant to be caught.”
Job seekers, workers involved in workplace accidents, and athletes are among those typically subject to forensic tests. For them, immunoassay testing is appropriate and is based on the Mandatory Guidelines for Federal Workplace Drug Testing Programs, developed by the U.S. Department of Health and Human Services.
Because much of UDT today has its roots in forensic applications, the methods and mindsets of simple immunoassay testing are often used in clinical settings. These tests are subject to a high number of false positives; therefore, only positive results are typically sent for confirmatory testing to avoid falsely accusing people of drug use that might have dire consequences, such as job loss.
“This is problematic,” Passik said. “An injured worker who is using drugs and has a false negative result is potentially at risk if the physician uses a forensic mindset and only confirms positive test results. If the injured worker’s pain medications are mixed with whatever drugs he may be abusing, he could suffer an overdose. Or, his addiction could worsen since it is not being detected by the workers’ comp claims administrator.”
Immunoassay tests are generally cheap, fast and readily available. However, they are not designed for, nor are they very effective for, many clinical applications on their own.
“Take a worker who is being prescribed pain medications and is overusing them. The worker runs out of his or her medication and then borrows some from a friend or family member and even further supplements by abusing heroin when these are unavailable,” Passik said. “If his result on an immunoassay test comes back positive for an opioid, this lends a false sense of security that it is, in fact, the prescribed opioid that caused the result. This result is actually a ‘clinical false negative’ for the non-prescribed opioid and heroin. If the clinician has a forensic mindset that sets out simply to catch people but not falsely accuse them, the testing would end there.”
Another example might be seen in the worker prescribed an opioid for pain but also using cocaine who knows not to use it within two to three days of doctors’ visits to avoid testing positive on the immunoassay. The immunoassay test would likely yield a false negative, and testing would, again, end there. “This worker could be quite vulnerable and might even engage in the type of self-deception whereby he convinces himself that he has no drug problem because he can stop in time to produce a negative specimen for cocaine, ”said Passik.
The mixing of cocaine or heroin and prescribed and borrowed pain medications would make the worker susceptible to an overdose and to other drug interactions or to triggering his addiction. But the medical provider in this case would have no idea the person is abusing drugs.
“That’s the rub,” Passik said. “If I were using UDT in a worker’s comp setting, I would have a more flexible policy that allows the provider to use his clinical judgment to determine whether to send either positive or negative results from immunoassay tests to a lab for confirmation testing, or simply skip the immunoassay test and go straight to the lab.”
Immunoassay tests often produce false negative results because of 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 occur, because certain immunoassay tests 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.
Liquid chromatography tests, on the other hand, enable detection of a much more expansive list of drugs. This is significant, as virtually all injured workers on opioid therapy would be expected to test positive on a drug screening. The liquid chromatography test could detect which opioid was present in the injured worker’s system and at which levels.
In a 2012 study that analyzed results for point-of-care tests using immunoassay in physicians’ offices or labs, Millennium Health found 27% of the test results were incorrectly identified as positive for oxycodone/oxymorphone. The low sensitivity of immunoassay tests can mistakenly identify codeine, morphine or hydrocodone as the same drugs. Similarly, the study results showed the immunoassay tests missed the identification of benzodiazepines in 39% of the results.
One example of clinical chromatography is liquid chromatography tandem mass spectrometry (LC/MS-MS). These tests are far more accurate than immunoassay tests, can identify parent medication and metabolites and identify specific medications, rather than just drug classes.
“Professionals can now accurately test with both great sensitivity and specificity to understand whether patients are taking their prescribed medication, avoiding the use of non-prescribed licit controlled substances and whether or not they are using illicit drugs, which allows for better clinical decision making,” Passik explained. “LC/MS-MS results are now rapidly available to clinicians, allowing for a much greater integration of these results into clinical practice.”
In fact, Passik says much of the growth in the use of LC/MS-MS in recent years is because of the speed with which results can now be obtained, often within 24 hours.
In terms of drug monitoring for injured workers, Passik says immunoassay testing alone does not provide the physician with an accurate basis on which to make good clinical decisions. These tests may be positive for opiates – which, if the person has been prescribed opiates, would be expected.
“In this case, a positive result would need to be sent to the lab to confirm that the opioid detected in the test was solely the medication prescribed and there are no other licit — or illicit — drugs present. The immunoassay positive result by itself doesn’t provide enough information,” Passik said. “However, if the worker is well known to the prescriber and has a long history of UDTs showing he is taking his medications as prescribed, the provider might decide the immunoassay test result will suffice at that point. But, again, it would need to be in the context of appropriate results of UDTs and a clinical exam that do not suggest otherwise.”
Beyond the confusion about the types of UDT, a handful of unscrupulous clinicians are overusing the tests by performing them in their offices or labs they own, regardless of the patient’s risk factors for abuse or overdose. Payers are overcharged by these providers, as they do more testing than is necessary and charge for the initial test, analysis and confirmatory test (because virtually all tests on injured workers receiving opioid therapy would be positive), resulting in three separate bills.
There are also questions surrounding the frequency with which these tests should be performed on a given injured worker. Passik and other experts say the frequency of the tests should be determined by a medical provider based on the injured worker’s risk factors. An injured worker who is depressed, male, a smoker and has a personal 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 is eager to do, or is already doing, light duty work. It’s a tough call, and, so far, it is not an exact science.
“If the patient is older and has no history of addiction or other risk factors, you would probably test her a couple of times a year,” Passik said. “But a coal miner in southeastern Kentucky who has been traumatized from an accident, has addiction history in his family, lives in an area where he can make money [by selling the drugs] — that’s a high risk person who likely needs to get tested more often. Most people fall in between, so it’s best to rely on the clinician’s extensive training and individual assessments of their patients and potential risk factors to consider when developing a treatment plan.”
Part of the decision making on the part of medical providers involves figuring out strategies to integrate the two methods of testing, immunoassay and chromatography – “specificity when you need it and the frequency when needed so you can do it in the most cost effective fashion,” Passik said. “The tests should be integrated in a smart way.”
The nature of workplace injuries is such that more testing up front may be required. “Unfortunately, workers’ compensation is heavily loaded with high-risk patients,” Passik said. “They tend to be younger, traumatized because they are injured, and suffer from depression — all of which are risk factors for addiction.”
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 UDTs performed for each injured worker.