A prospective analysis of injury severity among helmeted and nonhelmeted bicyclists involved in collisions with motor vehicles

To evaluate the impact of helmet use on injury severity, patient information was prospectively obtained for all bicyclists involved in collisions with motor vehicles seen at a level-I trauma center from January 1986 to January 1989. Two hundred ninety-eight patients were evaluated; in 284 (95.3%, study group) cases there was documentation of helmet use or nonuse. One hundred sixteen patients (40.9%) wore helmets and 168 (59.1%) did not. One hundred ninety-nine patients (70.1%) had an ISS <15, while 85 (29.9%) were severely injured (ISS >15). Only 5.2% of helmet users (6/116) had an ISS >15 compared with 47.0% (79/168) of nonusers (p < 0.0001). The mean ISS for helmet users was 3.8 compared with 18.0 for nonusers (p < 0.0001). Mortality was higher for nonusers (10/168, 6.0%) than for helmet users (1/116, 0.9%; p < 0.025). A striking finding was noted when the group of patients without major head injuries (246) was analyzed separately. Helmet users in this group still had a much lower mean ISS (3.6 vs. 12.9, p < 0.001) and were much less likely to have an ISS >15 (4.4% vs. 32.1%, p < 0.0001) than were nonusers. In this group, 42 of 47 patients with an ISS >15 (89.4%) were not wearing helmets. We conclude that helmet nonuse is strongly associated with severe injuries in this study population. This is true even when the patients without major head injuries are analyzed as a group; a finding to our knowledge not previously described. This implies that nonusers of helmets tend to be in higher impact crashes than helmet users, since the injuries suffered in body areas other than the head also tend to be much more severe. It is possible that at least some of the “protection” afforded helmet wearers in previous studies may be explained by safer riding habits rather than solely a direct effect of the helmets themselves.