1. From the Thrombosis Service (J.W.E.) and Population Health Research Institute (J.W.E., S.R.M., S.S.A., C.X., S.Y.), Hamilton Health Sciences, Hamilton, Canada; Department of Medicine, McMaster University, Hamilton, Ontario, Canada (J.W.E., S.R.M., S.S.A., S.Y.); and University and the Royal Infirmary of Edinburgh, Edinburgh, Scotland, UK (K.A.A.F.).