1. Ottawa Hospital and Department of Medicine, University of Ottawa (M.S., D.D.), Ontario, Canada.
2. Ottawa Hospital Research Institute (M.S., BD., D.D.), Ontario, Canada.
3. Sunnybrook Hospital, University of Toronto, Ontario, Canada (T.F., D.J.G., R.S.).
4. Foothills Medical Centre, University of Calgary, Alberta, Canada (M.D.H., B.K.M.)