1. Primary Care Research Group, Institute of Health Services Research, University of Exeter Medical School, Exeter, Devon, U.K.
2. NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital and University of Exeter Medical School, Exeter, Devon, U.K.
3. Peninsula Collaboration for Leadership in Applied Health Research and Care (PenCLAHRC), University of Exeter Medical School, Exeter, Devon, U.K.