1. Department of Clinical Pathology; Sunnybrook Health Sciences Centre, and the Department of Laboratory Medicine and Pathobiology, University of Toronto; Toronto Ontario Canada
2. University of Ottawa Centre for Transfusion Medicine, Ottawa Hospital Research Institute, and the Department of Medicine, Ottawa Hospital; and
3. Clinical Epidemiology Program; Ottawa Hospital Research Institute; Ottawa Ontario Canada
4. Department of Pathology; Beth Israel Deaconess Medical Center and Harvard Medical School; Boston Massachusetts