Comparison of eight commercial on-site screening devices for drugs-of-abuse testing

Eight commercially available on-site drugs-of-abuse testing devices for det ecting cannabinoids (THC-COOH), opiates (OPI), cocaine (COC). amphetamines (AMP), metamphetamines (MET) and benzodiazepines (BZO) were evaluated. The used urine specimens suspected of being drug positive were all confirmed by gas chromatographic/mass spectrometry (GC/MS). For AMP and MET, sensitivit ies varied between 83 and 95% and specificities between 98 and 100%. Corres pondingly, sensitivities between 88 and 98% and specificities between 95 an d 100% were observed for THC-COOH. For BZO, sensitivities varied between 91 and 97% and specificities between 97 and 100%. Only a few confirmed positi ve samples were available for OPI and COC. the sensitivities being between 83 and 100% and 100%, respectively. On-site devices did not always find ext remely high drug concentrations. False-negative results were found with AMP in particular. Pholcodine, commonly used as medicine, was observed to give false-positive results with most of the devices and was not, however, incl uded in given crossreactivity tables. It was found that the devices differe d markedly with respect to interpretation of test results and to ease of te st performance, leading to the suggestion that different criteria for selec ting on-site devices for either emergency laboratories in hospitals or for police stations and prisons should be used. Since the overall specificity o f any of the devices was not 100% and false positives were identified, we f ound it important to confirm any positive screening test result.