1. Ottawa Health Research Institute, Ottawa Hospital, Ottawa, Ontario, Canada
2. Centre for Community Health and Health Evaluation Research, Children’s and Women’s Health Centre of British Columbia, Vancouver, British Columbia, Canada
3. Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada
4. Department of Health Care and Epidemiology, University of British Columbia, Vancouver, British Columbia, Canada
5. British Columbia Injury Research and Prevention Unit, Vancouver, British Columbia, Canada
6. Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
7. Centre for Health Services and Policy Research, University of British Columbia, Vancouver, British Columbia, Canada