1The MRC Lifecourse Epidemiology Unit, Southampton General Hospital, University of Southampton, Southampton SO16 6YD, UK
2NIHR Musculoskeletal Biomedical Research Unit, Institute of Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK
3Section of Clinical Epidemiology, Department of Health Sciences Research, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
4SF Co-ordinating Center, 185 Berry Street, Lobby 4, 5th Floor, Suite 5700, San Francisco, CA 94107-1762, USA
5Centre for Metabolic Bone Diseases (WHO Collaborating Centre), University of Sheffield Medical School, Beech Hill Road, Sheffield S10 2RX, UK