[1] Univ Sheffield, Sch Med, WHO Collaborating Ctr Metab Bone Dis, Sheffield S10 2RX, S Yorkshire, England
[2] Malmo Univ Hosp, Dept Orthopaed, Malmo, Sweden
[3] Erasmus Univ, Med Ctr, Inst Publ Hlth, Rotterdam, Netherlands
[4] Stockholm Sch Econ, Dept Econ, S-11383 Stockholm, Sweden