1. Primary Care and Population Sciences, University of Southampton, Southampton, UK
2. Biostatistics, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, London, UK
3. Centre for Applications of Health Psychology, University of Southampton, Southampton, UK
4. Health Psychology Section, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, London, UK
5. Institute of Psychiatry, Psychology & Neuroscience, King’s College London, London, UK
6. Department of Gastroenterology, Southampton University Hospital, Southampton, UK
7. Department of Gastroenterology, King’s College Hospital, London, UK
8. Academic Department of Psychological Medicine, King’s College London, London, UK