1. is NIHR Research Fellow Academic unit of primary health care, School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol BS8 2PS;
2. University Hospitals Bristol NHS Foundation Trust;
3. in Electronic Health Records and Clinical Epidemiology Dept of Public Health and Epidemiology, University College London Medical School;
4. of primary health care Academic unit of primary health care, School of Social and Community Medicine, University of Bristol.