Downstream Medical Cost of Repealing Universal Motorcycle Helmet Laws

BACKGROUND: While repeal of universal motorcycle helmet laws has been linked to increased crash-related morbidity, earlier work evaluating the impact of repeal on crash-related costs is primarily limited to pre-post differences that neglect to account for underlying temporal trends. In this context, we sought to evaluate the impact of universal motorcycle helmet law repeal on crash-related costs using multiple-group interrupted time series methods. STUDY DESIGN: We evaluated the impact of Michigan's universal motorcycle helmet law repeal on inflation-adjusted inpatient costs associated with motorcycle crashes. We used data from the Healthcare Cost and Utilization Project State Inpatient Databases from 2009 to 2015. Michigan's repeal occurred in April 2012. We performed a multiple-group interrupted time-series analysis comparing Michigan and 4 control states chosen for geographic and sociodemographic similarity. RESULTS: A total of 19,685 patients aged 21 years and older were identified, of whom 5,280 were from Michigan. Universal motorcycle helmet law repeal was associated with a $5,785 (95% CI $3,022 to 8,548, p < 0.001) increase in inpatient costs per motorcycle crash patient in Michigan. This corresponded to a 26% increase in average cost per patient and $4.5 million/y excess annual expenditure during the study period. There was no association between repeal and cost change in the control group ($47, 95% CI -$1,094 to 1187, p = 0.9). CONCLUSIONS: Universal motorcycle helmet law repeal is associated with a 26% increase in crash-related inpatient costs. As policy repeal has occurred in 33 US states, a substantial portion of nationwide medical costs associated with motorcycle crashes may be potentially preventable.