Positivity rates of drugs in patients treated for opioid dependence with buprenorphine: A comparison of oral fluid and urine using paired collections and LC-MS/MS.

BACKGROUND: Drug testing is recommended as part of comprehensive monitoring for medication-assisted treatment. Alternative matrices including oral fluid offer a number of advantages when compared with conventional urine testing but are not as well characterized. This study aims to compare positivity rates of drugs and drug classes in oral fluid and urine as a measure of the clinical utility of oral fluid in the evaluation and treatment of patients with opioid use disorders.

METHODS: A retrospective review of paired oral fluid and urine test results from Millennium Health's laboratory database was performed for 2746 patients with reported prescriptions for buprenorphine products used in the treatment of opioid dependence. Specimens were tested using quantitative LC-MS/MS for 34 medications, metabolites and illicit drugs.

RESULTS: A number of medications and illicit drugs were detected at comparable or higher rates in oral fluid vs. urine such as cocaine (15.7% vs. 7.9%), opiates (13.4% vs. 10.0%), oxycodone (8.6% vs. 3.7%), hydrocodone (3.0% vs. 1.2%) and others. Lower detection rates were observed in oral fluid vs. urine for benzodiazepines (6.6% vs. 8.7%), cannabinoids (15.5% vs. 19.5%), oxymorphone (1.8% vs. 3.1%) and hydromorphone (0.8% vs. 4.5%).

CONCLUSIONS: Clinicians may find oral fluid advantageous for detection of specific drugs and medications in certain clinical situations. Understanding the relative differences between urine and oral fluid can help clinicians carefully select tests best suited for detection in their respective matrix. To our knowledge, this is the largest inter-matrix patient comparison study using paired collections and direct to definitive testing.