Teschke et al. BMC Public Health 2012, 12:765 http://www.biomedcentral.com/1471-2458/12/765 Page 7 of 9 Table 5 Associations between whether helmet was worn and trip or personal characteristics, variables retained in adjusted analysis only, each variable on its own (unadjusted) and in multiple logistic regression (adjusted) (Continued) Education Some high school Completed high school Some post-secondary education Completed college/ technical diploma Completed university degree Completed graduate degree Significant associations in bold. * Row percent. 7/6 19/21 71/48 68/57 190/59 123/21 (54/46) (48/52) (60/40) (54/46) (76/24) (85/15) 0.43 (0.13 – 1.42) 0.30 (0.15 – 0.59) 0.47 (0.29 – 0.76) 0.38 (0.24 – 0.61) 1 (reference) 1.80 (1.04 – 3.12) 0.42 (0.11 – 1.70) 0.30 (0.13 – 0.68) 0.61 (0.35 – 1.06) 0.43 (0.25 – 0.74) 1 (reference) 1.29 (0.70 – 2.40) Few studies have examined conspicuous clothing use and those that have suggest it is less common than use of helmets or lights at night. The clothing colours and types studied were not always defined or similar. A study in Alberta, Canada observed 16% of cyclists wearing yel- low, orange or red clothing on the torso, and 19% wear- ing white [18]. A study in the UK observed 10% wearing fluorescent or reflective clothing [20]. In self-report studies, 30% reported regular use of fluorescent colours in New Zealand [21] and 23% reported always use in Australia [13]. Only one study examined features asso- ciated with use and they found highly visible clothing to be associated with helmet use [20]. In our study, con- spicuous clothing use and helmet use were not associated. As with studies of equipment use, studies of injury prevention related to safety equipment have focused on helmets. Enough studies have examined the associ- ation between helmets and injuries to allow reviews and meta-analyses. Helmets have been shown to reduce head and face injuries (and increase neck injuries) in the event of a crash [28] and this type of post-crash protection has been emphasized in North America. In contrast, there has been little research directly examining the effectiveness of lights or con- spicuous clothing as a means of preventing crashes. This may be because this type of study is much more difficult to conduct than studies of injury type and se- verity that dominate the literature on helmets. A New Zealand study [21] found that cyclists who reported always wearing fluorescent colours had lower risks of crashes and days off work. They also found a lower crash risk among those who reported always using a back light at night. Kwan and Mapstone [29] reviewed the literature on visibility aids for cyclists and pedes- trians. They concluded that daytime visibility improved with white, yellow, orange, and red materials, and that night-time visibility aids (lights especially, but also re- flective clothing) enhanced detection and recognition and shortened reaction times of observers. More re- cent studies support these results [13,18]. Our study design did not allow analyses of the risk of crashes with the various types of safety equipment reported here. We were able to examine various surrogates of severity (e.g., transport by ambulance, hospitalization) and found that none of these safety equipment types was associated with injury severity, after controlling for factors such as route infrastructure, weather, and demographics [30]. This study had a number of limitations. It collected data from injured cyclists who attended a hospital emer- gency department, so may not be representative of all cyclists. The cyclists in this study, despite being recruited via an injury study and despite having many potential participants who were not contactable, mirror characteristics of cyclists in North America, i.e., domin- antly male, young, and educated [3,31]. An exception is that the sample included mainly frequent cyclists, likely a reflection of the fact that more time spent cycling offers greater opportunity to be injured. The study used self-reports by injured cyclists about safety equipment use. Our results compared favourably to studies using observations of cyclists in the field [10–12,15- 18,20,22,23,25]. This may be because self-reporting about a single trip (in this case, the injury trip) is well recalled and accurately reported. In addition, we used deliberate question ordering and wording to reduce the chance that responses aimed at conforming to behav- ioural norms and laws. For example, we purposely asked about helmet use indirectly by querying the colour of the helmet, instead of whether a helmet was worn. Other questions that might be affected by social desirability bias are those on alcohol and drug use. In our study, 10% of cyclists self-reported drinking in the 6-hour time frame prior to the trip. In studies that measured blood alcohol levels in more severely injured adult cyclists (fatally injured or hospitalized), 10, 14 and 19% had levels over 0.08 g/dL [11,23,32], suggesting that our mode of