Background and aims Bicycling may be less appealing in parts of the world where cycling is less safe. Differences between jurisdictions suggest route design is key to improving safety and increasing ridership. Previous studies faced difficulties in effectively assessing denominators for risk calculations and controlling confounding. This paper describes the advantages of the case-crossover design of the Bicyclists' Injuries and the Cycling Environment study to address these challenges to observational studies of cycling safety.
Methods Injured cyclists were recruited from the emergency departments of five hospitals in Vancouver and Toronto, Canada. In 18 months, 690 participants were successfully recruited and interviewed. Each participant was interviewed to map the route of their injury trip, identify the injury site and select two control sites at random from the same route. Infrastructural characteristics at each study site were scored by site observers who were blinded as to whether sites were crash or comparison sites. Analyses will compare infrastructural variables between case and control sites with conditional logistic regression.
Discussion This study presents a novel application of the case-crossover design to the evaluation of relationships between infrastructure and cycling safety while controlling confounders and exposure to risk. It is hoped that the value of this method and the efficiency of the recruitment process will encourage replication in other locations, to expand the range of cycling infrastructure compared and to facilitate evidence-based cycling infrastructure choices that can make cycling safer and more appealing.
- crossover studies
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Funding The study was funded by the Heart and Stroke Foundation of Canada and the Canadian Institutes of Health Research (Institute of Musculoskeletal Health and Arthritis and Institute of Nutrition, Metabolism and Diabetes). CCOR recognises funding from the Natural Sciences and Engineering Research Council of Canada, and MW and MAH acknowledge funding from the Michael Smith Foundation for Health Research. MAH recognises funding from the Public Health Agency of Canada. MAH, MC and MW received additional funding from the Canadian Institutes of Health Research. The opinions expressed herein are those of the authors and not necessarily those of the funding agencies. Early drafts of this research protocol benefitted from comments and suggestions from participants in the 2005–6 Bridge Program Grant Development Course at the University of British Columbia and from anonymous reviewers affiliated with the funding agencies.
Competing interests None.
Ethics approval This study received ethis approval from ethics boards at the University of British Columbia, University of Toronto, St Paul's Hospital, Vancouver General Hospital, St Michael's Hospital and Toronto University Health Network.
Provenance and peer review Not commissioned; externally peer reviewed.