Toxicological oral fluid results among Spanish drivers testing positive on on-site drug controls from 2013 to 2015.

Background: Driving under the influence of drugs (DUID) increases the risk of serious injury or death in traffic accidents. The aim of this study was to provide information about DUID in Spanish drivers.

Methods: 10,064 oral fluid samples were collected from Spanish drivers that tested positive on the roadside using the Dräger DrugTest 5000 (DDT5000) between 2013 and 2015. Samples were collected using Quantisal and analysed by LC-MS/MS at the Toxicology Laboratory of the Institute of Forensic Science of the University of Santiago de Compostela.

Results: Drivers were mainly young men (85.1% male, 29.7 ± 8.1 years old). In 98.5% of cases, LC-MS/MS results confirmed at least one of the positive results detected on the roadside. Cannabis (82.4%) and cocaine (42.1%) were the most commonly detected drugs. Poly-drug use was observed in 42.7% of drivers, mostly for all illicit drugs (>80%) except for cannabis (42.6%). Illicit drug and single-drug use was more frequent among drivers under 35 years old, and medicines and poly-drug use more common among drivers older than 35 years old. The on-site device performance was calculated using both the DDT5000 cut-offs and the LC-MS/MS method LOQs. Sensitivity (>73% vs >58%), specificity [>94% for all the compounds regardless the cut-offs used, except for cannabis (71%)] and accuracy (>87.5% with both cut-offs) fulfilled the DRUID Project requirements in all cases.

Conclusion: LC-MS/MS confirmation result was negative in only 1.5% of the cases. The DUID driver profile was a young man, consuming cannabis or a combination of cannabis and cocaine.