A univariate analysis of characteristics associated with serious traumatic events is outlined in Table 3. Except for helmet use, [emphasis mine] there were no statistical differences between those commuters who experienced a serious traumatic event and those who did not. Thirteen percent (6) of commuters who did not wear a helmet experienced a serious traumatic event, compared with 5% (43) of those who did (p 0.023). [emphasis mine] In an additional analysis comparing commuters who reported a traumatic event with those who reported a serious traumatic event, lack of helmet use was the only statistical difference between the two groups (p 0.013).

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Analysis of our study reveals two important findings [emphasis mine] that have not been previously reported. First [emphasis mine], as discussed above, there were no statistical differences in gender, age, BMI, skill level, or prior traumatic events between those commuters who experienced a traumatic or serious traumatic event and those who did not. This suggests that with proper safety practices, adults with no bike commuting experience are no more likely to be injured than adults with years of commuting experience. Second [emphasis mine], although the incidence rate of traumatic events is relatively low per 100,000 miles commuted, it translates into nearly 20% of commuters experiencing a traumatic event during the yearlong study period. Stated another way, Portland commuters experience one traumatic event per every 6,670 miles commuted. If these cyclists continue commuting at their current rates (1,620 miles/yr), they should experience one traumatic event every 4 years, on average.5 It is therefore imperative that all bike commuters are encouraged to wear helmets. In our analysis, helmets were associated with a lower risk of serious traumatic event (unadjusted OR 0.32; 95% CI, 0.12– 0.89). [emphasis mine]