Helmet Use, Clinical Outcomes, and Short-Term Direct Cost After Repeal of Nebraska’s Universal Motorcycle Helmet Law

BACKGROUND: On January 1, 2024, Nebraska repealed its universal motorcycle helmet law for riders aged ≥21 years with a valid Class M license. We evaluated changes in helmet use, clinical outcomes, and short-term direct institutional costs following repeal. STUDY DESIGN: In this multicenter retrospective cohort study, motorcycle crash patients treated at five ACS-verified Level I-III trauma centers in eastern Nebraska before and after repeal were compared by law era and helmet status. Helmet-use trends were assessed using segmented binomial logistic regression. Cost analyses were restricted to patients with positive direct institutional costs using survivor-only and log-transformed models. RESULTS: Among 467 patients (241 pre-repeal, 226 post-repeal), helmet use declined from 84.2% to 20.4% after repeal (p<0.001). Segmented regression demonstrated an immediate reduction in helmet use after repeal (OR 0.17, 95% CI 0.06-0.44; p<0.001), consistent with adjusted individual-level analysis (aOR 0.04, 95% CI 0.03-0.07; p<0.001). Post-repeal, non-helmeted riders had greater unadjusted head-injury burden and more neurosurgical interventions. After adjustment, non-helmeted status remained independently associated with neurosurgical intervention (aOR 3.10, 95% CI 1.03-9.35; p=0.044), but not BIG score ≥2, severe traumatic brain injury composite, or mortality. Adjusted log-transformed analyses showed lower short-term direct institutional costs among non-helmeted riders (cost ratio 0.68, 95% CI 0.54-0.86; p=0.001), likely reflecting differences in injury patterns and procedural utilization rather than reduced economic burden. CONCLUSIONS: Nebraska's helmet-law repeal was associated with an immediate and sustained reduction in helmet use. Non-helmeted riders had higher adjusted odds of neurosurgical intervention despite similar adjusted severe brain injury and mortality outcomes. Lower short-term institutional costs should not be interpreted as economic neutrality because they exclude downstream rehabilitation, disability, productivity losses, and societal costs.