1. L. K. F. Temple, R. S. McLeod, and S. Gallinger are in the Department of Surgery, University of Toronto, Mount Sinai Hospital, Samuel Lunenfeld Research Institute, Toronto, ON, Canada M5G 1X5.
2. J. G. Wright is in the Departments of Surgery, Public Health Sciences, and Health Policy, Management and Evaluation, University of Toronto, The Hospital for Sick Children, Toronto, ON, Canada M5G 1X8.