Frank X Scheuermeyer1,2, Clare L Atzema3,4. 1. Department of Emergency Medicine, St Paul's Hospital, University of British Columbia, Vancouver, BC, Canada. frank.scheuermeyer@gmail.com. 2. Center for Health Evaluation and Outcomes Sciences, University of British Columbia, Vancouver, BC, Canada. frank.scheuermeyer@gmail.com. 3. Division of Emergency Medicine and Department of Medicine, Sunnybrook Health Sciences Center, University of Toronto, Toronto, ON, Canada. 4. ICES, Toronto, ON, Canada.