Statistical analyses Analysis will be by intention to treat, using all available data from randomly assigned patients according to group assignment. Comparison between groups will be performed using chi-square tests or logistic regression for binary variables and with two sample t-test or linear regression models for continuous variables. Data will be analyzed using the SPSS version 19 (SPSS Inc, Chicago, Illinois) and SAS version 9.2 (SAS Institute, Cary, NC).