Validity testing of commercial urine cocaine metabolite assays: II. Sensitivity, specificity, accuracy, and confirmation by gas chromatography/mass spectrometry

A comprehensive validity assessment study was performed on eight commercial urine assays for detection of cocaine use. Sensitivity, specificity, and accuracy of each assay were evaluated by analyzing, in random order and under blind conditions, specimens spiked with known drug concentrations and clinical specimens obtained from human subjects after intravenous cocaine use. Commercial assay results were compared with gas chromatography/mass spectrometry (GC/MS) assay of the same specimens for benzoylecgonine. All of the assays examined were determined to have utility in screening for cocaine use, with the exception of the KDI Quik Test®, which was not a reliable test for detection of cocaine use. Major differences in sensitivity, specificity, and confirmation rate by GC/MS were noted among the assays, differences which should be taken into consideration when implementing a urine screening test for cocaine use or interpreting test results involving use of these assays.