23rd Annual Pain Medicine Meeting 2024

Patient profile:

• 70-year-old female patient w/ hx of rheumatoid arthritis, hip osteoarthritis, lumbar spondylosis, and long-standing methadone use for pain management presented to our interdisciplinary pain clinic seeking to establish care after her previous provider relocated.

Management:

UDT ordered during onboarding for methadone weaning plan

• Urine Drug screening (UDS)results:

-Consistent with methadone use

- False-positive for buprenorphine

• Patient denied buprenorphine use

• CURES (Controlled Substance Utilization Review and Evaluation System)database supported patient's claim

• Methadone not refilled during visit

• Repeat UDS yielded negative results for buprenorphine

•Cross-reactivity between methadone and buprenorphine in immunoassay-based UDS is a recognized phenomenon that can complicate interpretation[2]

•The CEDIA® Buprenorphine II Assay (Thermo Scientific) is used to detect buprenorphine and its major metabolites.

•This assay Identifies methadone as possible cross-reactant due to structural similarities and shared metabolites [5]

•Negative screening cut off at 100,000 ng/mL

•Previous studies indicate that methadone concentrations exceeding 320,000 ng/mL, can occur in individuals with chronic use, may lead to significant cross-reactivity [3]

Cutoff level importance:

•Manufacturer (CEDIA® Buprenorphine II Assay) cutoff: 10 ng/mL

- Many labs (including ours) use 5 ng/mL; increasing chances of false-positive

- Increasing the cutoff from 5 ng/mL to 10 ng/mL enhances the specificity of the assay

Implications of false-positive results:

•Impact on patient care and provider-patient relationship [4]

•Potential for unwarranted suspicion of non-adherence or illicit drug use

•Risk of punitive measures or loss of trust

The possibility for a UDT to yield false-positive results due to cross reactivity between medications highlight the importance of awareness amongst providers regarding inherent limitations of testing, as false-positive results can significantly impact patient care in addition to the provider-patient relationship

23rd Annual Pain Medicine Meeting 2024

THE IMPACT OF A FALSE-POSITIVE URINE DRUG TESTING RESULT DUE TO METHADONE/BUPRENORPHINE CROSS REACTIVITY: A CASE REPORT

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