Statistical methods
Data analysis was performed using SPSS 22.0 statistical software. Measurement data conforming to normal distribution were expressed as mean ± standard deviation, and t-test was used for comparison between groups. Non-normally distributed measurement data were represented by M[P25; P75], and the comparison between groups was performed using the Mann–Whitney U nonparametric test. The enumeration data were described in the form of the number of cases (percentage), and the chi-square test was used for comparison between groups. P < 0.05 was considered statistically significant.