1. University of Liverpool, Department of Biostatistics, Liverpool, L69 3GL, England2University College London, National Institute for Cardiovascular Outcomes Research (NICOR), London, EC1A 4NP, England
2. University College London, National Institute for Cardiovascular Outcomes Research (NICOR), London, EC1A 4NP, England3Computer Science Corporation, Kings Cross, London, N1C 4AG, England
3. University College London, National Institute for Cardiovascular Outcomes Research (NICOR), London, EC1A 4NP, England4Academic Surgery Unit, University of Manchester, Manchester Academic Health Science Centre, University Hospital of South Manchester, Manchester, M23 9LT, UK
4. University College London, National Institute for Cardiovascular Outcomes Research (NICOR), London, EC1A 4NP, England
5. Department of Cardiac Surgery, Bristol Heart Institute, Bristol Royal Infirmary, Bristol, BS2 8HW, England
6. South West Cardiothoracic Centre, Derriford Hospital, Derriford, Plymouth, PL68DH, England
7. Cardiovascular Biomedical Research Unit, Royal Brompton Hospital, London, SW3 6NP, England
8. University of Manchester, Manchester Academic Health Science Centre, Centre for Health Informatics, Vaughan House, Manchester, M13 9GB, England
9. Department of Cardiothoracic Surgery, James Cook University Hospital, Middlesbrough, TS4 3BW, England