Statistical analysis
The software SPSS 24.0 was used for the data analysis. The median
(range/lower quartile and upper quartile, M-Range/QL & QU) was used to
describe its concentration and tendency of dispersion, since not all the
quantitative data were shown as the normal distribution.
The Kruskal-Wallis H test was used for the comparison between multiple
independent groups. The enumeration data were represented as rate or
composition ratio and the chi-square test was applied for comparisons
between groups. The binary non-conditional logistic regression with
single factor and multi-factor analyses were conducted to check the
influencing factors of related variables. The predominant factors from
the single factor analysis were considered for the further multi-factor
regression analysis. The forward stepwise regression method was also
adopted in the present study and p values lower than 0.05 and 0.10 were
used as criteria. The two-tailed test was applied in all the analyses
and p<0.05 was considered significant. The p value for the
comparison of two groups was modified to 0.017.