1. MRC/CSO Social and Public Health Sciences Unit & Robertson Centre for Biostatistics, School of Health & Well Being, Clarice Pears Building, University of Glasgow , Byres Rd, Glasgow G12 8TA , UK
2. Health Service Research, College of Medicine and Health, University of Exeter , Heavitree Rd, Exeter, EX2 4TH , UK
3. Faculty of Health Sciences and National Institute of Public Health, University of Southern Denmark , Studiestræde 6, 1455, Copenhagen , Denmark
4. University of Exeter Medical School, Royal Cornwall Hospital , Truro , UK
5. Primary Care Research Group, University of Exeter Medical School, St Luke’s Campus , Exeter , UK
6. Department of Cardiology, Odense University Hospital , J. B. Winsløws Vej 4, 5000, Odense C , Denmark
7. REHPA , Vestergade 17, 5800, Nyborg , Denmark
8. Department of Clinical Research, University of Southern Denmark , Campusvej 55, DK-5230 Odense M , Denmark