Urine Drug Testing Among People Prescribed Opioid Medications for Chronic Pain: Useful Tool or Blunt Instrument?

Guidelines recommend using urine drug testing (UDT) to monitor patients prescribed opioid medications for chronic pain; however, interpreting results can be challenging. This study used UDT results and clinical data from a multisite trial that sought to improve clinicians’ adherence to opioid prescribing guidelines. Adult patients (N=638) who received long-term opioid therapy for chronic pain were included. Two physicians with expertise in pain and addiction determined whether UDT results were concerning for unhealthy substance use or diversion (i.e., selling, trading, or giving away prescribed medication), uncertain, or not concerning.

  • Most patients were 45–64 years old; 60% had mental health-related diagnoses, and 17% had a substance use disorder diagnosis.
  • Overall, 37% of patients had ≥1 concerning UDT result. In 24% of these patients, it was due to non-detection of a prescribed substance; in 23% of these patients, it was due to detection of a non-prescribed substance (most commonly cocaine or benzodiazepines).
  • Having a concerning UDT result was associated with younger age (18–34 years old versus >65; adjusted odds ratio [aOR], 4.8), mental health-related diagnoses (aOR, 1.6), and substance use disorder diagnoses (aOR, 2.3).
  • 35% of patients had ≥1 uncertain UDT result.

Comments: In this study, UDT frequently produced concerning results that would affect management decisions. For example, detection of a non-prescribed benzodiazepine would indicate an elevated overdose risk. However, there was also substantial uncertainty regarding results even among expert adjudicators. UDT results are only one piece of clinical data that should influence prescribing decisions and misinterpretation could lead to harms (e.g., involuntary opioid tapering is associated with elevated overdose risk). Clinicians need skills to interpret UDT results, humility to recognize uncertainty, and a strategy for responding to unexpected results in patient-centered ways.

Aaron D. Fox, MD

Reference: Larochelle MR, Cruz R, Kosakowski S, et al. Do urine drug tests reveal substance misuse among patients prescribed opioids for chronic pain? J Gen Intern Med. 2021;10.1007/s11606-021-07095-8.

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