Cozart(R) RapiScan Oral Fluid Drug Testing System: An Evaluation of Sensitivity, Specificity, and Efficiency for Cocaine Detection Compared with ELISA and GC-MS Following Controlled Cocaine Administration
Oral fluid has become a widely accepted alternative matrix for drugs of abuse detection. Immunoassays have been developed for on-site testing of cocaine and metabolites in oral fluid. The performance of the Cozart RapiScan Oral Fluid Drug Testing System (CRS) was evaluated in comparison with Cozart Microplate Enzyme Immunoassay Cocaine Oral Fluid Kit (COC ELISA) and gas chromatography-mass spectrometry (GC-MS) at several screening and confirmation cutoffs, including those proposed by SAMHSA and those currently in use in the U.K. Oral fluid samples (n = 1271) were collected prior to and following controlled clinical cocaine administration. CRS provides a qualitative screen at a preset cutoff of 30 µg/L. Sensitivity, specificity, and efficiency for CRS (30 µg/L) as compared with COC ELISA with a cutoff of 30 µg/L were 92.1%, 91.8%, and 92.0%. The comparison of CRS (30 µg/L) with the 8-mg/L proposed SAMHSA confirmation cutoffs for cocaine and/or benzoylecgonine exhibited a sensitivity of 82.7%, a specificity of 94.5%, and an efficiency of 87.6%. For this study, an alternative CRS cutoff of 20 µg/L was also evaluated. Performance characteristics of CRS (20 µg/L) at the proposed SAMHSA confirmation cutoffs were 89.9%, 89.7%, and 89.8%, respectively. At cutoffs in use in the U.K., 30-µg/L CRS screen and 15-µg/L GC-MS cutoffs for cocaine, benzoylecgonine, and/or ecgonine methyl ester sensitivity, specificity, and efficiency were 89.4%, 92.2%, and 90.7%, respectively. Cozart RapiScan had performance similar to the COC ELISA assay for the detection of cocaine exposure and suitable sensitivity and specificity at the proposed SAMHSA cutoffs.