Objective The increasing frequency of bicycle-related injuries is due to the growing elderly population and their increasing physical activity. This study aimed to compare the protective effects of helmets on bicycle-related injuries in elderly individuals compared with those in younger adults.

Methods Data from the Korean emergency department–based Injury In-depth Surveillance database from eight emergency departments during 2011–2016 were retrospectively analysed. The subjects sustained injuries while riding bicycles. Cases with unknown clinical outcomes were excluded. Covariates included mechanism, place and time of injury. The primary outcome was traumatic brain injury (TBI) incidence, and the secondary outcomes were in-hospital mortality and severe trauma. The effects of helmets on these outcomes were analysed and differences in effects were determined using logistic regression analysis. Subsequently, the differences in the effects of helmets use between age groups were examined by using interaction analysis

Results Of 7181 adults, 1253 were aged >65 years. The injury incidents showed a bimodal pattern with peaks around ages 20 and 50 years. Meanwhile, the helmet-wearing rate showed a unimodal pattern with its peak at age 35–40 years; it decreased consistently with age. By multivariate analysis, helmet-wearing was associated with a reduced TBI incidence (OR 0.76; 95% CI 0.57 to 0.99) and severe trauma (OR 0.78; 95% CI 0.65 to 0.93). The effects of helmets increased in elderly individuals (TBI (p=0.022) and severe trauma (p=0.024)).

Conclusion The protective effects of helmets on bicycle-related injuries are greater for elderly individuals, thus reducing TBI incidence.