1. Post Graduate Program in Epidemiology, Federal University of Rio Grande do Sul , Porto Alegre, Rio Grande do Sul , Brazil
2. Statistics Department, Universidade Federal do Rio Grande do Sul , Porto Alegre, Rio Grande do Sul , Brazil
3. Post Graduate Program in Collective Health, Federal University of Bahia , Salvador, Bahia , Brazil
4. Faculdade de Medicina & Hospital das Clinicas/EBSERH, Universidade Federal de Minas Gerais , Brazil
5. Post Graduate Program in Epidemiology and Hospital de Clínicas de Porto Alegre, Federal University of Rio Grande do Sul , Porto Alegre, Rio Grande do Sul , Brasil