1. Department of Psychology, Social Work and Allied Health Sciences, Glasgow Caledonian University, Glasgow, UK
2. Health Economics and Health Technology Assessment and National Institute for Health Research Complex Reviews Support Unit, University of Glasgow, Glasgow, UK
3. Department of Nursing and Community Health, Glasgow Caledonian University, Glasgow, UK
4. GCU London, Glasgow Caledonian University, London, UK
5. Chelsea and Westminster Hospital NHS Foundation Trust, London, UK
6. Chalmers Sexual Health Centre, NHS Lothian, Edinburgh, UK
7. Chief Scientist Office/Medical Research Council Social and Public Health Sciences Unit, University of Glasgow, Glasgow, UK