Statistical analysis
Continuous variables are presented as mean ± standard deviation (SD) and
were compared with Student t or Mann–Whitney test. For paired data,
paired Student t and Wilcoxon signed rank test were used. Categorical
variables are expressed as numbers and percentages and were compared by
use of Pearson’s χ2 or Fisher’s exact test. Statistical significance was
set at a 2-tailed probability level of <0.05. Statistical
analyses were performed using IBM SPSS Statistics (version 24.0; IBM
Corp, Armonk, NY).