[1] Univ Campus Biomed Roma, Dept Med, Unit Endocrinol & Diabet, Via Alvaro del Portillo 21, I-00128 Rome, Italy
[2] IRCCS, Ist Ortoped Galeazzi, Milan, Italy
[3] Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA 94143 USA
[4] San Francisco VA Med Ctr, San Francisco, CA USA
[5] Oregon Hlth & Sci Univ, Portland, OR 97201 USA
[6] Univ Pittsburgh, Grad Sch Publ Hlth, Dept Epidemiol, Ctr Aging & Populat Hlth, Pittsburgh, PA 15260 USA
[7] Stanford Univ, Dept Med, Stanford, CA 94305 USA
[8] Univ Calif San Diego, Dept Med & Publ Hlth, La Jolla, CA 92093 USA