Imagine that a clinician calls your laboratory enquiring about a patient’s recent drug testing results. She performed a point-of-care drug screen in her office and your laboratory completed confirmation testing. She has multiple questions about drug components, drug cutoffs, cross reactivity, and potential false positive results, all in the quest to determine if the patient is compliant with all medications. This is a common tale. Seems daunting, right? Where does one start in order to help this clinician make patient care decisions from complex drug testing results? The session on Tuesday afternoon titled “Interactive Pain Management Case Studies: Clinician and Laboratory,” helped us to navigate through this complex area of laboratory medicine.
Paul Jannetto, PhD, introduced the session by addressing the need for experts in drug testing interpretation. He stressed that “laboratory tests for controlled substance monitoring are not harmonized and interpreting test results is not always clear cut or straightforward due to complicated metabolic pathways and pharmaceutical impurities or spiked/adulterated samples.” With that impetus, Jannetto helped set the tone for the remainder of the session.
Sarina Yang, PhD, spoke on the fundamentals of pain management and provided a unique approach to presenting her talk, “Clinical Utility and Limitations of Qualitative and Quantitative Laboratory Testing for Pain Management.” She took a poll that asked audience members about pain management practices in their laboratories. Polling questions focused around the AACC/AAPM guidelines on pain management testing, the different testing platforms available (point of care, immunoassay, mass spectrometry) along with the different matrices and metabolic pathways/challenges when interpreting tests. The polling questions were well integrated into the presentation and challenged audience members’ knowledge throughout. Yang emphasized that the new AACC/AAPM Laboratory Medicine Practice Guidelines (LMPG) on using laboratory tests to monitor drug therapy in pain management patients is a useful tool when interpreting tests for ordering clinicians. Yang taught the basics of drug interpretation by seamlessly integrating them into case examples while simultaneously engaging with the audience. This interactive approach provided the necessary context for audience members to learn the fundamental concepts behind interpreting drug testing results in an engaging way.
Nancy Bratanow, MD, then brought the perspective of the practicing pain management physician to the discussion. She used interactive case studies along with Jannetto’s input from the laboratory’s perspective to teach the audience about drug interpretation concepts. These case studies were presented in the form of phone call skits, which was a refreshing method to maintain audience attention and interest.
One particular case titled “Where’s Pauldo,” perfectly illustrated the difficulties prescribing clinicians face when attempting to interpret complex drug testing results.
“Pauldo” was a patient of Bratanow’s who was prescribed lorazepam (a benzodiazepine) and oxycodone (an opioid) and had submitted a urine specimen for drug adherence testing. His screening by immunoassay identified oxycodone as presumptively positive but all other drug screening components were negative, including benzodiazepines. The plot thickened as confirmatory testing by mass spectrometry revealed oxycodone as well as oxymorphone. Bratanow needed to know: Did Pauldo take his lorazepam as prescribed? Why was oxymorphone confirmed positive even though it wasn’t prescribed? Jannetto helped break down the case and address Bratanow’s concerns.
First, he pointed out that oxymorphone is a direct metabolite of oxymorphone and its confirmed presence at the concentration ratio in Pauldo’s sample was consistent with Pauldo taking oxycodone as prescribed within the last several days. Jannetto went on to describe why lorazepam may have tested negative by the benzodiazepines immunoassay screen. He explained that most benzodiazepines screens are intentionally designed to detect oxazepam. More importantly, lorazepam heavily metabolizes to lorazepam glucuronide which tends to have extremely low cross reactivity with oxazepam-based benzodiazepine immunoassays.
Jannetto recommended direct confirmation using mass spectrometry to determine the presence of lorazepam. Upon completion of testing, lorazepam was confirmed to be positive in Pauldo’s sample. Jannetto was able to systematically answer Bratanow’s concerns through his detailed knowledge of drug testing concepts and ultimately determine the patient was fully compliant with the medications prescribed.
The interactive approach the speakers took to explain the drug testing interpretation space was innovative. With the complexity of drug testing increasing, this session provided important context for what it takes to perform quality drug interpretation for pain management in a refreshingly engaging and educational way. Maybe drug interpretations for pain management are not so painful after all.