Statistical analysis
Descriptive statistics are used to report frequencies, and the means are given with their 95% confidence intervals. The χ2test of homogeneity and independence and Fisher’s exact test were used to compare categorical variables (P<0.05 was considered significant). Analysis of variance, Student’s t test, or the Mann-Whitney U test was used compare quantitative variables, as appropriate. The analyses were performed in IBM SPSS Statistics 24.0, and the graphs were generated with Microsoft® Excel® 2010.