1. Graduate Studies Program in Epidemiology, School of Medicine, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
2. Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, North Carolina
3. Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis, Minnesota
4. Department of Medicine, Baylor College of Medicine, Houston, Texas
5. Department of Biostatistics, School of Public Health, University of North Carolina, Chapel Hill, North Carolina