Drivers who tested positive for cannabis in oral fluid: a longitudinal analysis of administrative data for Spain between 2011 and 2016

Abstract Objectives: This study aimed to assess the association between positive roadside tests for delta-9-tetrahydrocannabinol (THC) and other driving-impairing substances and THC concentrations and the age and gender of THC-positive drivers. Design: This study is based on administrative data. Setting, participants and exposures: National administrative data on drivers who tested positive in confirmation analysis of driving-impairing substances in oral fluid were assessed (2011–2016, 179 645 tests). Primary and secondary outcome measures: Frequencies of positivity for THC, THC alone and THC