1. Methods in Epidemiologic, Clinical, and Operations Research-MECOR-program, American Thoracic Society/Asociación Latinoamericana del Tórax, Montevideo, Uruguay. 2. Instituto Nacional de Enfermedades Respiratorias, Ciudad de Mexico, Mexico. 3. Department of Population and Public Health Science, Keck School of Medicine, University of Southern California, Los Angeles (CA) USA. 4. Divisão de Pneumologia, Instituto do Coração, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo (SP) Brasil.