1 DISCOVERY Group, University of Exeter Medical School, University of Exeter, Exeter, UK.
2 Wolfson Institute of Population Health, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
3 Department of Health Systems and Population Health, School of Public Health, University of Washington, Seattle, US.
4 University of Melbourne Centre for Cancer Research, Victorian Comprehensive Cancer Centre; Department of General Practice, University of Melbourne, Victoria, Australia.
5 GP and National Institute for Health and Care Research Academic Clinical Lecturer, Centre for Primary Care and Health Services Research, University of Manchester, Manchester.