Figure 1

Odds ratios of multiple logistic regression analysis for each variable. The white part of the bar indicates 95% CI or more. Continuous (age) and ordinal variables (risk), are expressed as the ratio of the odds from the 3rd to the 1st quartile (listed in the numbers after the corresponding variable). Dichotomous variables are coded as follows: Gender (0 = male, 1 = female), helmet (1 = use of helmet, no use of helmet).