1. Division of Thoracic Surgery, Hospital São Lucas Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
2. Division of Thoracic Surgery, Universidade de São Paulo, Faculdade de Medicina, Hospital das Clinicas, Instituto do Coração, São Paulo, Brazil
3. Department of Statistics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
4. Division of Thoracic Surgery, Santa Casa de Misericórdia da Bahia, Salvador, Brazil
5. Division of Thoracic Surgery, Hospital Santa Casa de Misericórdia de Porto Alegre, Porto Alegre, Brazil
6. Department of Thoracic Surgery, Hospital Federal de Base do Distrito Federal, Brasília, Brazil
7. Department of Thoracic Surgery, Hospital de Messejana, Fortaleza, Brazil
8. Department of Surgery, Universidade Federal do Ceará, Fortaleza, Brazil
9. Department of Thoracic Surgery, Universidade de Caxias do Sul, Caxias do Sul, Brazil