1WHO Collaborating Centre for Metabolic Bone Diseases, University of Sheffield Medical School, Beech Hill Road, Sheffield, S10 2RX, UK
2Gothenberg, Sweden
3Department of Orthopaedics, Malmo General Hospital, S-214 01, Malmo, Sweden
4Department of Public Health, Erasmus Medical Center, Rotterdam, The Netherlands
5Department of Economics, Stockholm School of Economics, Stockholm, Sweden