Evaluation of four oral fluid devices (dds, drugtest 5000, drugwipe 5+ and rapidstat) for on-site monitoring drugged driving in comparison with UHPLC-MS/MS analysis

New Italian legislation on driving under the influence of drugs considers oral fluid (OF) as a possible alternative drug testing matrix. On this basis, the present research was carried out to evaluate the applicability of four commercial on-site OF drug screening devices, namely DDS1, Drugtest 50001, Drugwipe 5+1 and RapidSTAT1, in a real operative context. Preliminarily trained police officers tested randomly stopped drivers with two different kits side-by- side during roadside patrols. A central laboratory confirmed on-site kits’ results by UHPLC–MS/MS analysis of the saliva specimen remaining after the screening analysis. 1025 drivers were submitted to the OF tests: 11.6% were positive for cocaine and metabolites, 11.1% for THC, 6% for amphetamines and amphetamine-type designer drugs and 2.3% for ketamine. The sensitivities of the kits were 81% (RapidSTAT1), 82% (DDS1), 90% (Drugwipe 5+1) and 97% (Drugtest 50001) for cocaine and 38% (DDS1), 47% (Drugwipe 5+1), 72% (RapidSTAT1) and 92% (Drugtest 50001) for THC. Drugtest 5000 was the only kit showing an acceptable sensitivity for on-site application. Only Drugtest 50001 and RapidSTAT1 could be evaluated for amphetamines and methamphetamines: Drugtest 50001 showed a sensitivity of 100% in the case of amphetamines and 86% for methamphetamines, while RapidSTAT1 90% and 76% respectively. Nowadays, ketamine is not included in the target analytes of any on-site devices, but it was systematically included in the UHPLC– MS/MS confirmatory analysis. To ensure adequate reliability, MS confirmation of on-site OF screening tests is anyway always necessary, due to the presence of a significant number of false positive results even when using the commercial kit with the best performance.