Effects of repealing the motorcycle helmet law in Michigan

•Helmet use significantly decreased following repeal of Michigan's helmet law.•There has been an increase in rate of head injury following the repeal.•Non-helmeted motorcyclists were more likely to present with a GCS ≤ 8.•Significantly more non-helmeted patients died prior to discharge.•Only drug/alcohol use was a significant independent risk factor for mortality.

BackgroundIn 2012, Michigan repealed its universal helmet law. Our study assessed the clinical impact of this repeal.MethodsOur trauma database was queried retrospectively for 2 motorcycle riding seasons before and 3 seasons after repeal. On-scene death data was obtained from the Medical Examiner.ResultsHelmet use in hospitalized patients decreased after the helmet law repeal. Non-helmeted patients had a significant increased rate of head injury. Non-helmeted patients were more likely to die during hospitalization. While, helmet use and drugs/alcohol status significantly affected the risk for head injury, only drug/alcohol had a significant effect on overall mortality.ConclusionsFollowing helmet law repeal, helmet use has decreased. Helmet status and drug/alcohol use was found to significantly increase risk of head injury. Although overall mortality was only affected by drug/alcohol use, non-helmeted patients did have a higher inpatient mortality. These findings deserve furthermore study and may provide a basis for reinstating the universal helmet law.