Statistical analysis
IBM SPSS v. 21 (Chicago, IL, USA) was used as the statistical method.
Continuous data were expressed as means ± SD or median. Categorical
variables are given as a number (percentage) of patients. The
differences between the groups were compared using the chi-square test,
Fisher-exact test, Student t-test, and Mann-Whitney U test. Differences
in eGFR among the two groups over time were analyzed using
repeated-measures ANOVA. Sphericity was determined by the Mauchly’s
analysis when the p-value > 0.05. When the Mauchly’s
analysis did not identify sphericity, we used repeated-measures ANOVA
with Greenhouse-Geisser correction. All statistical tests used the
software SPSS version 22.0 (IBM Corp., Armonk, NY, USA). The
significance value was accepted as p < 0.05.