Comparing the characteristics of electric scooter and bicycle injuries: a retrospective cohort study

Electric scooters (e-scooters) and bicycles are used for similar purposes as transportation. Few studies have shown that e-scooter and bicycle accidents differ in terms of user-profiles and injury characteristics. Still, there is missing information comparing the specific injury types, the overall incidence, and the relative risk of these accidents. We aimed to compare the characteristics, severity, and rate of e-scooter and bicycle injuries and assess their relative risk. We conducted a retrospective register study comparing e-scooter and bicycle injuries treated in emergency departments in Helsinki between 1.1.2022 and 31.12.2023. Data was collected from the Helsinki University Hospital electronic data pool. We evaluated injury severity using the Abbreviated Injury Score. The incidence and relative risk for e-scooter accidents was assessed based on the usage data of all shared e-scooters, and the estimation of bicycle trips was made utilizing several travel surveys. There were 677 e-scooter accidents and 1889 bicycle accidents during the study period. E-scooter riders were younger, with a mean age of 33 (SD 13), compared to cyclists with a mean age of 47 (SD 17). The incidence of e-scooter accidents leading to ED care was 7.8 per 100,000 trips, whereas the estimated incidence of bicycle accidents was 2.2 per 100,000 trips. The relative risk for e-scooter accidents leading to ED care was 3.6 (CI 3.3-3.9), compared to bicycle accidents, E-scooter riders were more likely to ride intoxicated (incidence 29% vs. 8%) and less likely to wear a helmet (4% vs. 28%) compared with cyclists. Head injuries occurred more often with e-scooter riders (46% vs. 31%) compared to cyclists, whereas torso injuries were more common among cyclists (11% vs. 5%) than e-scooter riders. A higher proportion of e-scooter accidents happened during the nighttime, between 10 PM and 8 AM, compared to cyclists (40% vs. 31%). Intoxicated riding was also more common among e-scooter riders during the nighttime (50% vs. 22%). E-scooter and bicycle accidents differ in terms of patient characteristics and injury types. The high incidence of head injuries and intoxicated riders among e-scooter riders suggests that preventive measures on e-scooters are warranted. E-scooter riding very likely poses a higher risk for injuries than cycling.