Roberto Oliveira Dantas1, Rachel Aguiar Cassiani2. 1. Department of Medicine, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, SP, 14049-900, Brazil. rodantas@fmrp.usp. 2. Public Hospital of São Paulo State, Ribeirão Preto, SP, Brazil.