[1] Ctr Hosp Sao Joao, Serv Pneumol, Oporto, Portugal
[2] Univ Porto, Fac Med, Dept Epidemiol Clin Med Predit & Saude Publ, P-4100 Oporto, Portugal
[3] Univ Porto, Inst Saude Publ, P-4100 Oporto, Portugal
[4] Ctr Hosp Sao Joao, Serv Radiol, Oporto, Portugal
[5] Ctr Hosp Sao Joao, Serv Anat Patol, Oporto, Portugal