1. Department of Critical Care Medicine, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
2. Department of Anesthesia
3. Interdepartmental Division of Critical Care Medicine
4. Institute of Health Policy, Management, and Evaluation, and
5. Department of Anesthesiology and
6. Department of Medicine, University of Toronto, Toronto, Ontario, Canada; and
7. Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York