1 Centre for Medical Informatics, Usher Institute of Population Health Sciences and Informatics, The University of Edinburgh, Edinburgh EH8 9DX, UK.
2 Division of General Internal Medicine and Primary Care, Brigham and Women's Hospital, Boston, MA, USA.
3 Centre for Medical Informatics, Usher Institute of Population Health Sciences and Informatics, The University of Edinburgh, Edinburgh EH8 9DX, UK. Electronic address: aziz.sheikh@ed.ac.uk.