Statistical analysis
The prevalence of lifetime self-reported STDs was expressed
as a percentage and it was calculated as the number of participants
with prior history of STD divided by the total number
of patients included in this analysis. Descriptive analysis was
carried out and Chi-square statistic was used to assess differences
of categorical data. The magnitude of the associations
between explanatory variables and the outcome of interest –
history of STD – was estimated by the odds ratio (OR) with 95%
confidence interval (95% CI). The independent effect of potential
exposure variables was assessed by multivariate analysis
using logistic regression. All variables with p-values equal to or
less than 0.20 in the univariate analysis were included in multivariate
modeling. A backward deletion strategy was applied
and those variables with p-values equal to or less than 0.05
remained in the final model. SAS System® was used for data
analysis and Paradox® Windows for the database management.