Traumatic brain injury among two-wheeled motor vehicle riders in Utsunomiya, Japan: a comparison between mopeds and motorcycles

Purpose Two-wheeled motor vehicles are dichotomized into mopeds and motorcycles (MCs) based on their engine capacity. While efforts have been made, mostly by European researchers, to evaluate the possible difference in the frequency/severity of riders’ traumatic brain injury (TBI) between the two categories, the results have been inconsistent. Methods To evaluate whether such differences exist in Japan, a single-center, retrospective observational study was conducted on two-wheeled motor vehicle riders wearing a helmet during high-energy road traffic accident (RTA). Between January 2011 and December 2017, 127 moped and 128 MC helmeted riders involved in RTAs had been treated in our institution. Results Moped riders were significantly older than MC riders (50.7 ± 25.0 years vs. 35.1 ± 18.6 years, p = 0.04). The frequency of TBI was significantly higher in moped riders than in MC riders (21.3% vs. 10.9%; p = 0.03). However, the frequency of other bodily injuries did not differ significantly. Among the riders with TBI, neither injury severity nor outcomes differed significantly. Multivariate regression analysis showed that the presence of altered mental status was predictive of TBI (OR 23.398; 95% CI 9.187–59.586; p