[1] Hosp Univ Mar, IMAS, Serv Cirurgia Gen Abdominal & Torac, E-08003 Barcelona, Spain
[2] Univ Autonoma Barcelona, Sch Med, Barcelona, Spain
[3] Hosp Univ Mar, IMAS, Serv Avaluacio & Epidemiol Clin, Barcelona, Spain
[4] ASPB, UPF, IMAS, Unitat Docent Med Prevent & Salut Publ, Barcelona, Spain
[5] CIBERESP, Sao Paulo, Brazil