Drug use pattern of suspected drug-influenced drivers in Hungary (2019-2023).

Between 2019 and 2023, blood and urine samples of 6229 suspected impaired drivers were analysed, with a positivity rate of 91.5 %. Classical illicit drugs were detected in 4693 drivers, medicines in 850 drivers, stimulant new psychoactive substances (sNPS) in 928 drivers and synthetic cannabinoid receptor agonists (SCRAs) in 657 drivers. The consumption of cannabis, N-ethyl-norpentedron, and N-ethyl-hexedrone increased significantly over time, while the consumption of five SCRAs declined. These changes were concordant with the seizure data for the entire country. 74.2 % of drug-positive drivers were deemed impaired. Impairment was determined by fixed concentration limits in 3538 cases, multi-drug use in 507 cases, and clinical symptoms (when only one active substance with no impairment limit was present in the blood) in 217 cases. To evaluate clinical tests, the prevalence of positive and negative clinical findings was compared for amphetamine/methamphetamine, THC, MDMA, alprazolam, and clonazepam above and below their fixed concentration limits. Only alprazolam showed a significantly higher frequency of positive clinical signs above the limit. This finding suggests that the current protocol of medical examination in Hungary is inadequate for diagnosing impairment when only one active substance without a defined threshold is detected in the blood. Given that sNPS was detected in 24.1 % of drivers, the medical investigation system requires a major revision. The aim of this study was to investigate the illicit and licit drug consumption of suspected impaired drivers in Hungary and to present the disadvantages of the system currently used for diagnosing and proving impairment.