Statistics
SPSS 22.0 statistical software was used to analyze the data. All measurement data were tested for normality. The measurement data conforming to normal distribution were compared between the two groups by independent sample t test, and the data were expressed by± s ; The measurement data that did not conform to the normal distribution were expressed by M (P25, P75) , and the nonparametric Wilcoxon rank sum test was used for comparison between groups. P < 0.05 was statistically significant.