Zeitschrift für klinische Toxikologie
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A Comparison of Urine and Oral Fluid Drug Testing

Sarah Smiley, Amadeo Pesce, Kevin Krock, Richard Thomas, Agnes Cua and Sonali Vittachi

Urine has become a staple for drug screening; however limitations due to the inconvenience of the collection process and a lack of integrity due to possible adulteration, substitution, and diversion have paved the way for other matrices such as oral fluid. A clinical study was conducted to compare the use of oral fluid versus urine for compliance with monitoring rehabilitation, pain, behavioural health, and internal medicine patients. Patients (n=142) undergoing drug monitoring at 25 clinics within 12 states provided paired oral fluid and urine specimens. The oral fluid specimens were collected with Quantisal^® saliva collection devices the same day as the urine collection. All specimens were analyzed by validated high sensitivity liquid chromatography- tandem mass spectrometry procedures (LC-MS/MS) using AB Sciex 6500 LCMS systems for 26 drugs and/or metabolites. Of the 142 paired specimens, there was an agreement of 52.1% where 244 (7.66%) analytes were positive in both matrices and 2677 (84%) analytes were negative in both matrices, with a Cohen’s Kappa coefficient of 0.501 indicating there is a ‘moderate’ agreement. The analyte detected most frequently in both urine and oral fluid was buprenorphine, followed by amphetamine. In urine, higher rates of detection occurred with hydromorphone, norbuprenorphine, and oxazepam, while oral fluid saw higher rates of detection with methamphetamine, heroin metabolite 6-Monoacetylmorphine (6MAM), and morphine. Factors that are responsible for the difference of analytes detected between the two matrices include the length of detection in urine, the lower cut offs in the oral fluid analysis due to lower concentrations of drugs, and the physiological factors that cause detection rates to differ between the two matrices for certain drug classes. The authors conclude oral fluid drug testing may be an alternative to urine drug testing when illicit drug testing or recent drug use is the primary goal of drug testing.