Chronic Pain Update 2013: New Data and Perspectives - Episode 15
In this video clip, Charles E. Argoff, MD, describes the strengths and limitations of urine drug testing in chronic pain patients who are prescribed opioid medications.
In addition to tracking whether a patient is "using the medication that they’re telling you that they’re taking,” urine drug tests can turn up traces of herbal supplements undisclosed in a patient’s medication histories that can “interfere with a medicine that you would prescribe that isn’t even an opiate,” Argoff notes.
“Feverfew is a natural, aspirin-like product. Well, it’s important for me to know that a person is taking that, so that I can say, ‘Ok, well, let me caution you,’ Argoff says. “It’s all about safety and maximizing the benefit, so urine drug testing has (that) promise, if it’s done right.”
Argoff recommends using a “high sensitivity, high specificity type of urine drug testing” that allows physicians to ask for specific substances to screen, which is a feature that can accurately assess if “the person in front of you (is) at low, medium, or high risk of abuse and misuse of medication.”
Still, Argoff cautions that with respect to urine drug testing, metabolic variations in patients can cause unexpected or unexplained test results. Looking at the cytochrome P450 dependent process in particular — which metabolizes codeine to morphine in order for the drug to be effective — Argoff points out that “there are people in the world who do this ultra-fast … there are people who do it medium fast, and there are people who don’t do it at all. If you’re the person with pain and you’re prescribed acetaminophen with codeine following your surgery, wouldn’t you want to know where you stand?”
In addition to accounting for those variations ahead of time, physicians need to discuss each test outcome with the patient after the results are in, Argoff says.
“The person who orders the test has to be willing and able to sit down afterwards and say, ‘This is what your test showed. Let’s discuss. If everything is consistent, that’s great. If everything is not consistent, let’s talk about why this might not be consistent and have an open discussion,’” Argoff stresses. “If the person is misusing and abusing a treatment, it may mean that that person needs other treatment to help them with all their problems.”