Statistical analysis
Statistical analyses were performed using IBM SPSS Statistics for
Windows, version 20.0. (IBM Inc., Armonk, N, USA). The statistical level
of significance for all tests was p <0.05. To evaluate
the changes in the measurements obtained at different time points,
repeated measures analysis was adopted, and the LSD test was used for
multiple comparisons. The Bonferroni-adjusted Student’s t-test was used
to assess whether there was a difference between the PN and RN groups
for each repeated measurement. Logistic regression analysis was
performed to determine significant risk factors, and renal function
decline was defined as the decrease between the baseline value and that
obtained in the 3rd postoperative year. In univariate analysis, overall
survival (OS) was calculated by the Kaplan-Meier method, and the
log-rank test was performed. Cox regression analysis was performed to
identify significant prognostic factors. Variables significant at
the p <0.2 level in univariate analysis and variables
considered clinically significant were entered into the Cox regression
analysis.