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The Centers for Disease Control and Prevention in its new guideline on opioid use offers granular advice to clinicians on how to incorporate urine testing into a regimen for treating chronic pain with this class of drugs.

CDC’s guidance addresses two major public health concerns: management of chronic pain, and a worrying increase in the number of overdoses associated with prescription drug opioids. An upcoming AACC online conference also plans to discuss these issues at length, honing in on the opioid crisis’ impact on laboratory toxicology testing.

“More than 40 Americans die each day from prescription opioid overdoses, we must act now,” said CDC Director Tom Frieden, MD, MPH, in a statement. “Overprescribing opioids—largely for chronic pain—is a key driver of America’s drug-overdose epidemic.”

Primary care physicians are frequent prescribers of opioids in outpatient settings. CDC aims to guide these clinicians on how to safely treat patients with these drugs, while avoiding the possibility of overdose or other harms. The guidance also advises on alternatives to opioids, which may include nonopioid drugs or nonpharmacologic therapies.

CDC’s focus is on patients in outpatient settings, not for those getting active cancer treatment or end-of-life care. The agency issued 12 recommendations to advise clinicians on prescribing opioids for chronic pain outside these care settings.

On a topic of particular interest to laboratorians, CDC addressed the role of urine testing as a precursor to starting opioids for chronic pain use. Urine drug testing is a useful barometer for determining unreported use of pain medications and may also determine if a patient is not taking the medication as prescribed.

Clinicians should “consider urine drug testing at least annually to assess for prescribed medications as well as other controlled prescription drugs and illicit drugs,” CDC’s guidance advised.

Such tests should be part of an honest conversation between patient and doctor about opioid drug therapy. If a doctor suspects a patient is selling or sharing these drugs in lieu of taking them, it’s advised that they do a urine test to see if the medication can be safely discontinued. “A negative drug test for prescribed opioids might indicate the patient is not taking prescribed opioids, although clinicians should consider other possible reasons for this test result,” according to the guidance.

CDC also cautioned against urine testing for tetrahyrdocannabinol (THC), the psychoactive ingredient in marijuana. “Clinicians should not test for substances for which results would not affect patient management or for which implications for patient management are unclear. For example, experts noted that there might be uncertainty about the clinical implications of a positive urine drug test for [THC]."

CDC advised that clinicians familiarize themselves with the types of drugs urine tests screen for, how to interpret the results of these tests, and what drugs are included in the urine drug testing panels their practice uses. As an example, a positive “opiates” test may be useful in detecting substances like heroin, codeine, or morphine in a patient, but may not be able to detect certain types of opioids like methadone or oxycodone. CDC noted that most labs use specific oxycodone assays to look for this drug.

Immunoassay panels most often used for an initial urine drug test usually aren’t that expensive—it’s when confirmatory tests are needed that the costs go up. “The use of confirmatory testing…should be based on the need to detect specific opioids that cannot be identified on standard immunoassays or on the presence of unexpected urine drug test results,” according to the guidance.

Urine drug tests also have their limits in that they don’t provide specifics on dosage of opioids. The results aren’t always interpreted accurately, “and might sometimes be associated with practices that might harm patients (e.g., stigmatization, inappropriate termination from care),” CDC cautioned. Insurance doesn’t always cover these tests in full, and for clinicians, interpreting and relating these results to patients takes up time in their schedules.