1. Faculty of Wellbeing, Education and Language Studies, The Open University in Scotland , 10 Drumsheugh Gardens, Edinburgh EH3 7QJ , UK
2. MRC/CSO Social and Public Health Sciences Unit, University of Glasgow , Berkeley Square, 99 Berkeley St, Glasgow G3 7HR , UK
3. Robertson Centre for Biostatistics, University of Glasgow , Level 11, Boyd Orr Building, University Avenue, Glasgow G12 8QQ , UK
4. NHS Ayrshire and Arran, University Hospital Crosshouse , Kilmarnock Rd, Crosshouse, Kilmarnock KA2 0BE , UK
5. Primary Care Research Group, University of Exeter Medical School , St Luke’s Campus, Exeter EX1 2LU , UK
6. General Practice & Primary Care, University of Glasgow , 1 Horselethill Road, Glasgow G12 9LX , UK
7. NHS Forth Valley, Forth Valley Royal Hospital , Stirling Road, Larbert FK5 4WR , UK