A comparative evaluation of the instant-view 5-panel test card with OnTrak TesTcup Pro 5: comparison with gas...

This study compared the ability of two on-site testing devices, Instant-View Test Card and OnTrak TesTcup Pro 5, to discriminate negative from positive urine samples for cannabinoids, cocaine metabolite, opiates, amphetamines, and benzodiazepines. The on-site devices were evaluated in a precision study with fortified urine samples and in a clinical study with samples submitted for forensic urine drug testing. For precision, seven stocks were prepared per device. Each stock had all five analytes added in a random fashion at 0, 25, 50, 75, 125, 150, or 175% of cutoff. Ten aliquots per stock were assigned random numbers and analyzed by two individuals. The respective accuracies (defined as "% below cutoff samples that were negative + % above cutoff samples that were positive") for Instant-View Test Card and TesTcup were 74.3 and 87.1 for amphetamines; 82.1 and 90.7 for benzoylecgonine; 88.6 and 90.7 for benzodiazepines; 83.6 and 94.3 for morphine; 82.1 and 87.9 for cannabinoids; and 82.1 and 90.1% overall. In contrast to the on-site testing devices, instrumental testing with OnLine reagents had perfect precision. For the clinical study, submitted samples that had reached their disposal date were rescreened for the five drug groups. Fifty that had absorbance changes near the negative control for all five drug groups were selected as "negatives"; 240 samples with positive or multi-positive results (some between the 75% control and cutoff) and confirmed by GC-MS were chosen as "positives" (at least 45 per drug group). The non-positive drug groups in these samples added 150 additional presumptively negatives per drug group. Samples were assigned random numbers, and two individuals tested each sample. The respective accuracies in respect to GC-MS results for Instant-View Test Card and TesTcup were 95.8 and 91.7 for amphetamines; 100 and 100 for benzoylecgonine; 96.7 and 96.5 for benzodiazepines; 98.8 and 99.2 for opiates; 94.4 and 95.0 for cannabinoids; and 97.1 and 96.5% overall. The clinical study revealed that the Instant-View Test Card had low cross-reactivity (i.e., false negatives) for samples with amphetamine only and oxycodone. TesTcup had low cross-reactivity for samples with amphetamine only and hydrocodone and/or hydromorphone; it also had more cross-reactivity towards (i.e., false positives) sympathomimetic amines. In summary, the Instant-View Test Card was less precise than the TesTcup at or near the cutoff; with clinical samples, however, the percent accuracies of the two devices were similar.