Alcohol, illicit and non-illicit psychoactive drug use and road traffic injury in Thailand: a case-control study.

The objective of this study was to determine the relationship between alcohol use, psychoactive drug use and road traffic injury (RTI). A case-control study was conducted among drivers in Bangkok, Thailand. Two hundred cases and 849 controls were enrolled between February and November 2006. Cases who sustained a RTI were matched with four controls recruited from petrol stations within a 1-km radius of the reported crash site of the case. A positive alcohol breath test (> or =50mg/dl), and positive tests for the presence of illicit (amphetamine, cocaine, marijuana) and non-illicit psychoactive drugs (antihistamine, benzodiazepine, antidepressants), using gas chromatography/mass spectrometry (GC/MS) were documented as primary measures. There were significantly higher odds of an alcohol breath test > or =50mg/dl (adjusted odds ratio (OR) 63.6 (95% CI: 25.5-158.9)), illicit psychoactive drugs (adjusted OR 3.4 (95% CI: 1.7-6.6)) and non-illicit psychoactive drug (adjusted OR 3.1 (95% CI: 1.5-6.3)) among cases than controls. Even though driving under the influence of psychoactive drugs has been significantly linked to RTI, its contribution to road safety is much lower than driving under the influence of alcohol. With limited resources, the priority for RTI prevention should be given to control of driving under the influence of alcohol.