Performance characteristics of the Cozart® RapiScan Oral Fluid Drug Testing System for opiates in comparison to ELISA and GC/MS following controlled codeine administration

Abstract

Oral fluid is an interesting alternative matrix for drug testing in many environments, including law enforcement, workplace drug testing, and drug treatment facilities. Performance characteristics of the FDA-cleared, qualitative, Cozart® RapiScan Opiate Oral Fluid Drug Testing System (Opiate Cozart® RapiScan System or Opiate CRS) were compared to the semi-quantitative Cozart® Microplate EIA Opiate Oral Fluid Kit (Opiate ELISA) and to gas chromatography/mass spectrometry (GC/MS). The following oral fluid opiate cutoffs were evaluated: the GC/MS limit of quantification (LOQ) of 2.5mg/l; 15μg/l currently used for oral fluid testing in the United Kingdom (UK); 30μg/l (Opiate CRS cutoff); and 40μg/l, the proposed Substance Abuse and Mental Health Services Administration (SAMHSA) cutoff.Subjects provided informed consent to participate in this IRB-approved research and resided on the closed research ward throughout the study. Three oral codeine doses of 60mg/70kg were administered over a 7-day period. After a 3-week break, subjects received three doses of 120mg/70kg within 7 days. Oral fluid specimens (N=1273) were analyzed for codeine (COD), norcodeine (NCOD), morphine (MOR) and normorphine (NMOR) by GC/MS with an LOQ of 2.5μg/l for all analytes. MOR and NMOR were not detected in any sample; 26.5% of the specimens were positive for COD and 13.7% for NCOD.Opiate CRS uses a preset, qualitative cutoff of 10μg/l; this is equivalent to 30μg/l in undiluted oral fluid as the oral fluid collection process involves a 1:3 dilution with buffer. Sensitivity, specificity, and efficiency of Opiate CRS compared to Opiate ELISA were 98.6, 98.1, and 98.2% at a 30μg/l cutoff and 99.0, 96.2, and 96.6% at a 40μg/l cutoff. Compared to the much lower GC/MS LOQ of 2.5μg/l, sensitivity, specificity and efficiency were 66.8, 99.3 and 90.7%. Increasing the GC/MS cutoff to the current UK level yielded performance characteristics of 81.5% (sensitivity), 99.3% (specificity), and 95.4% (efficiency). Using a GC/MS cutoff identical to the preset Opiate CRS cutoff yielded sensitivity, specificity, and efficiency of 88.5, 99.2, and 97.5%, respectively. At the proposed SAMSHA confirmation cutoff of 40μg/l, sensitivity increased with little change in specificity and efficiency (91.3% sensitivity, 98.9% specificity, and 97.5% efficiency).Oral fluid is a suitable matrix for detecting drugs of abuse. Opiate CRS, with a 30μg/l cutoff, is sufficiently sensitive, specific and efficient for oral fluid opiate analysis, performing similarly to Opiate ELISA at the same cutoff, and having performance characteristics >91% when compared to GC/MS at the proposed SAMHSA cutoff.