Statistical analysis
The above-mentioned variables were expressed as mean ± standard
deviation (SDs), median (range) or number (percentage) of each group
according to the distribution and type of data, which were compared by
Student’s t-test, Mann-Whitney test, chi-square test or Fisher exact
test, respectively. Hazard ratios (HRs) were presented with their 95%
confidence intervals (CIs). Kaplan–Meier curves were used to estimate
the clinic outcomes and the significant differences between two groups,
which were compared with the log-rank test. The effects of risks on CIN
were identifed by log-binomial regression models with forward stepwise
selection. Statistical analyses were carried out using software programs
(SPSS for Windows, version 22.0; IBM Corporation, Armonk, NY, USA). All
tests were two-tailed and P -value of <0.05 was supposed
to be statistically signifcant.