Cocaine testing in fitness-to-drive assessments: comparison between hair analysis, urinalysis and self-reports

Introduction: Cocaine is one of the most commonly used illicit substance and may have a devastating impact on road safety. The detection of cocaine use is therefore of great significance in assessing fitness-to-drive. The aim of this study is to compare anamnestic declaration of cocaine use with the results of immunoassays in urine and the results of hair analysis in the fitness-to-drive assessment procedure used in Switzerland. We hypothesised that hair analysis will detect a higher number of clandestine cocaine users than urinalysis. Material and methods: Anamnestic declarations as well as the results of urinalysis and hair analysis were collected from fitness-to-drive reports. Urinalysis was performed with an immunoassay. Hair samples were analysed using liquid chromatography coupled with tandem mass spectrometry (LC-MS-MS). Results: Of a total population of 311 subjects (mean age 32.5 years), 38 admitted consumption of cocaine, in 7 cases the urine immunoassay was positive and 84 subjects tested positive for cocaine in hair analysis. The detection rate in hair analysis for cocaine was 12 times greater than that for urine testing and 1.4 times greater than that for anamnestic declaration. Apart from cocaine, the investigated population consumed cannabis (21 of 81 subjects), amphetamines (30 of 81 subjects) as well as, more rarely, opiates and methadone (included substitution treatment). Conclusions: The study results reveal that hair analysis is more effective than urinalysis and self-reports in identifying cocaine users in a fitness-to-drive assessment. Hair analysis provides long-term information about cocaine use and is therefore a useful tool for the identification and follow-up of cocaine users. Hair analysis should be included in every assessment of fitness-to-drive in subjects suspected of cocaine abuse.