Repeal of the Michigan helmet law: the evolving clinical impact.

Background: Michigan repealed a 35-year mandatory helmet law in April 2012. We examined the impact of this legislation on a level 1 trauma center.

Methods: A retrospective cohort study comparing the 7-month period before and the 3 motorcycle seasons after the helmet law repeal.

Results: A total of 345 patients were included in the study. Nonhelmeted riders increased from 7% to 28% after the repeal. Nonhelmeted crash scene fatalities were higher after the repeal (14% vs 68%). The nonhelmeted cohort had significantly higher in-patient mortality (10% vs 3%), injury severity score (19 vs 14.5) and abbreviated injury scale head (2.2 vs 1.3). Non-helmeted riders also had increased alcohol use, intensive care unit length of stay and need for mechanical ventilation. The median hospital cost for the non-helmeted cohort was higher (P < .05).

Conclusions: The impact of the Michigan helmet law repeal continues to evolve. Three years after this legislative change, we are now observing increased injury severity score, higher in-patient mortality, and worse neurologic injury.