1. Keele Cardiovascular Research Group, Centre for Prognosis Research, Keele University, Keele , Staffordshire, ST5 5BG , UK
2. Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine , 291 Campus Drive, Stanford, CA 94305 , USA
3. Cardiovascular Medicine, Thomas Jefferson University Hospital , 111 S 11th St, Philadelphia, PA 19107 , USA
4. Department of Medicine, McMaster University , 1280 Main Street West. Hamilton, Ontario L8S 4L8 , Canada
5. Department of Health Research Methods, Evidence, and Impact, McMaster University , 1280 Main Street West. Hamilton, Ontario L8S 4L8 , Canada
6. Population Health Research Institute , 237 Barton St E, Hamilton, Ontario, ON L8L 2X2 , Canada
7. Research Institute of St. Joseph's Hamilton , 00 W 5th St, Hamilton, Ontario, ON L8N 3K7 , Canada