1. Bone Research Unit, Academic Department of Geriatric Medicine, University of Wales College of Medicine, Llandough Hospital, Cardiff CF64 2XX, Wales, UK
2. Centre for Health Economics and Policy Studies, School of Health Science, University of Wales Swansea, Swansea, Wales, UK
3. Centre for Health Improvement Research and Evaluation (CHIRAL), The Clinical School, University of Wales Swansea, Swansea, Wales, UK
4. Medical Physics and Clinical Engineering Directorate, University Hospital of Wales, Heath Park, Cardiff, Wales, UK