[1] Univ Pavia, Dept Orthopaed & Traumatol, IRCCS Fdn Policlin San Matteo, I-27100 Pavia, Italy
[2] IRCCS Fdn Policlin San Matteo Fdn, Unit Clin Epidemiol & Biometry, I-27100 Pavia, Italy
[3] SDA Bocconi, Ctr Res Hlth & Social Care Management CERGAS, I-20136 Milan, Italy
[4] Univ Campania, Multidisciplinary Dept Medicosurg & Dent Specialt, I-80138 Naples, Italy