1. Newburn Surgery , Newcastle-upon-Tyne NE15 8LX , United Kingdom
2. Department of Health Services Research, Institute of Population Health Sciences, Waterhouse Building, University of Liverpool , Liverpool L69 3BX , United Kingdom
3. General Practice & Primary Care, Institute of Health & Wellbeing, University of Glasgow , Horselethill Road, Glasgow G12 9LX , United Kingdom
4. Faculty of Health Sciences and Wellbeing, Sciences Complex, City Campus, University of Sunderland , Chester Road, Sunderland SR1 3SD , United Kingdom
5. Academic Psychiatry and Regional Affective Disorders Service, Wolfson Research Centre, Campus for Ageing and Vitality, University of Newcastle , Newcastle-upon-Tyne NE4 5PL , United Kingdom