Data were analyzed using Stata 10 (College Station, NC). Standard
descriptive and univariate analysis was performed. Summary of the
results was presented as the mean, SD, and median with interquartile
ranges for continuous variables, whereas proportions were used to
describe the discrete variables. Continuous variables were analyzed
using the Wilcoxon signed-rank test for nonparametric variables. Oneway
analysis of variance with Bonferroni correction was used to
compare multiple groups. Differences between groups for discrete
variables were tested with χ2 or Fisher exact test, whereas McNemar
test was used to compare matched group outcomes. Significance was
set at P ≤ .05, whereas this was P ≤ .01 for Bonferroni correction