2.3. Statistical analysis

Statistical software SPSS19.0 was used for statistical analysis, and measurement data were expressed as mean ± standard deviation. For data conforming to normal distribution, the mean between two groups was compared by independent sample t test, and the mean between multiple groups was compared by one-way Anova. The data that do not fit the normal distribution are compared after normal transformation. Counting data were represented by the number of cases and percentage, and the chi-square test was used for comparison between groups. P < .05 was considered to indicate a statistically significant difference.