Contextual and temporal determinants of injury severity in electric micromobility: a comparative analysis of E-bikes and E-scooters

The rapid adoption of electric micromobility has reshaped urban transport while introducing significant and evolving safety challenges. Despite a growing volume of injury data, existing research has largely examined e-scooters and e-bikes in isolation, and conventional analytical approaches have routinely failed to account for the spatial and temporal structure of injury events. This study provides a comparative analysis of injury patterns and severity determinants among e-scooter and e-bike users in the United States, using 2,413 emergency department cases from the National Electronic Injury Surveillance System for 2021 and 2022. Cases were identified through product-code screening and reproducible narrative-based classification. Injury patterns were examined descriptively, followed by binomial logistic regression incorporating demographic, clinical, behavioral, temporal, and location-context characteristics. Cluster-robust standard errors accounted for dependence within NEISS location groups, while interaction terms examined whether the association between motor-vehicle involvement and severe outcomes varied across injury environments. E-bike users had a higher crude severe-outcome rate than e-scooter users (15.0% vs. 11.2%), although vehicle type was not independently associated with severe outcome after adjustment (OR = 1.071, 95% CI: 0.834–1.374, p = 0.591). Age, diagnosis, body region, drug involvement, and location context were significantly associated with severe outcomes. A significant interaction between location context and motor-vehicle involvement was observed (OR = 2.456, 95% CI: 1.070–5.639, p = 0.034), indicating that the association between motor-vehicle involvement and severe outcome varied across recorded injury environments. Drawing on a Safe Systems perspective, the study argues that effective policy must address the interaction between users, vehicles, and the built environment, prioritizing dedicated infrastructure and conflict reduction with motorized traffic over device-level regulation alone.