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 less than 15, while 85 (29.9%) were severely injured (ISS greater than 15). Only 5.2% of helmet users (6/116) had an ISS greater than 15 compared with 47.0% (79/168) of nonusers (p less than 0.0001). The mean ISS for helmet users was 3.8 compared with 18.0 for nonusers (p less than 0.0001). Mortality was higher for nonusers (10/168, 6.0%) than for helmet users (1/116, 0.9%; p less than 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 less than 0.001) and were much less likely to have an ISS greater than 15 (4.4% vs. 32.1%, p less than 0.0001) than were nonusers. In this group, 42 of 47 patients with an ISS greater than 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.(ABSTRACT TRUNCATED AT 250 WORDS)