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.