[1] Galician Hlth Serv, EOXI Lugo Cervo & Monforte Lemos, Lugo, Spain
[2] Univ Santiago de Compostela, Sch Med & Dent, Dept Surg & Med Surg Special, Santiago De Compostela, Spain
[3] IDIS Fdn, Epidemiol Stat & Res Methodol Unit, Santiago De Compostela, Spain
[4] IDIS Fdn, Epidemiol Stat & Res Methodol Unit, Lugo, Spain
[5] Univ Oviedo, Sch Med & Hlth Sci, Dept Surg & Med Surg Special, Oviedo, Spain