1. Department of Primary Care & Mental Health, Institute of Population Health, University of Liverpool , 1-3 Brownlow Street, Liverpool, L69 3GL , UK
2. King’s Health Economics, Health Services and Population Research, Department of Psychiatry, Psychology & Neuroscience, King’s College London , David Goldberg Centre 18 De Crespigny Park, London, SE5 8AF , UK
3. Population Health Sciences Institute, Faculty of Medical Sciences Newcastle University, Baddiley-Clark Building, Richardson Road , Newcastle upon Tyne NE2 4AX , UK
4. Population Health Sciences Institute, Faculty of Medical Sciences Newcastle University, Baddiley-Clark Building , Richardson Road, Newcastle upon Tyne NE2 4AX , UK
5. National Institute for Health Research Applied Research Collaboration, North East and North Cumbria, Cumbria, Northumberland, Tyne & Wear NHS Foundation Trust St Nicholas Hospital Gosforth , Newcastle Upon Tyne NE3 3XT , UK