Background: The objective of the current study is to determine how alcohol and illicit substance use contributes to motorcycle crash fatalities by examining the relationship between toxicology levels found postmortem and the behavior of riders and passengers in fatal motorcycle crashes. Materials and methods: All motorcycle fatalities in Miami-Dade County, FL, from 2009 to 2014 were reviewed using the Miami-Dade County Medical Examiner's toxicology reports and the corresponding crash reports. Results: Positive alcohol/illicit substance detection was found in 44% of our population of 227 fatalities. When compared with those with a negative alcohol/illicit substance detection, those with a positive alcohol/illicit substance detection were more likely to be found at fault of the crash (77% versus 50%, P < 0.001), more likely to be in a single-vehicle crash (47% versus 21%, P < 0.001) and less likely to wear a helmet (44% versus 64%, P = 0.002). However, there was no significant relationship between speeding and alcohol/illicit substance detection (29% versus 33%, P = 0.748). In addition, a regression analysis demonstrated that there was less helmet use and more single-vehicle crashes with higher blood alcohol concentration. Conclusions: In fatal motorcycle crashes, alcohol and illicit substance use had a significantly negative impact on the risk aversion of motorcycle fatalities in regard to fault, helmet use, and single-vehicle crashes.
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