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BACKGKROUND: Traffic-related trauma is an important contributor to morbidity and mortality in Canada, especially among children and young adults. Comparing exposure-based injury rates between travel modes and jurisdictions is a valuable tool towards improving safety. METHODS: We used injury data from the British Columbia Motor Vehicle Branch, trip diary data from the Metro Vancouver transportation authority, and population and provincial travel data from the Census to calculate crude fatality and injury rates for motor vehicle occupants, bicyclists, and pedestrians. We used three different denominators: population; person-trip; and distance travelled. RESULTS: Motor vehicle occupants had the lowest fatality rates using exposure-based denominators: 9.6 per 100 million person-trips and 0.97 per 100 million km. Bicyclists and pedestrians had similar fatality rates using one denominator (13.8 vs. 14.7 per 100 million person-trips, respectively), but bicyclists had a lower rate using the other (2.60 vs. 7.37 per 100 million km). For injuries, pedestrians had the lowest rate and bicyclists the highest using the person-trip denominator, whereas motor vehicle occupants had the lowest rate using the distance denominator, and bicycling and walking had similar rates. CONCLUSIONS: Risks of driving, walking and bicycling in British Columbia were similar to their risks in the United States. The injury and fatality rates for these three travel modes were intermediate compared to much higher rates among US motorcyclists and much lower rates among US bus passengers. Data improvements would enable transportation trauma rate calculations for Canada as a whole and for other modes of travel (transit, motorcycling).

Despite variation in Canadian privacy laws between provinces and territories, increasing legislative protection of personal privacy has imposed restrictions on health research across the country. The effects of these restrictions on patient recruitment include increased study costs, durations, and decreased participation rates. Low participation rates can jeopardize the validity of research findings and the accuracy of measures of association by introducing non-response, or participation bias. We constructed simulations to assess potential effects of non-response bias on the accuracy of measures of association in a hypothetical case-control study. Small biases that alter the probability of selecting an exposed case can lead to dramatic inflation or attrition of the odds ratio (OR) in case-control studies. ORs are more unstable and subject to error when the true probability of selecting an exposed case is greater, such that strong positive associations are subject to error even at low levels of bias. Well-powered, population-based epidemiological research is a cornerstone of public health. Therefore, when weighing the benefits of protecting personal privacy, the benefits of valid and robust health research must also be considered. Options might include special legislative treatment of health research, or the use of an “opt-out” (vs. the current “opt-in”) construct for consent in confidential research.