Opioid users in Louisiana know that such drugs can cause psychomotor and cognitive impairment in those who have yet to develop a tolerance. Such impairment can affect one's driving, which is why not a few drivers who cause crashes test positive for opioids. In 1993, 2% of all crash initiators tested positive for them, but in 2016, the percentage rose to 7.1%.
Researchers at Columbia University analyzed thousands of fatal two-car crashes in the Fatality Analysis Reporting System and looked at those drivers who tested positive for opioids. There were 1,467 in all. Of these 918 were deemed to be the crash initiators: nearly twice as many as those who were not. The most commonly used opioids were hydrocodone (32% of drivers), morphine (27%), oxycodone (19%) and methadone (14%).