Statistical analysis
Statistical analyses were conducted using SPSS software (version 22.0, SPSS Inc., Chicago, IL, USA). The data are expressed as medians and ranges or as frequencies (percentages). All tests were two tailed, andP <0.05 was considered significant. The values of continuous variables in the expressors and non-expressors were compared using the Mann-Whitney U test, and the Wilcoxon test was used to compare the value of continuous variables within the same group. The distributions of categorical variables were compared with the Fisher exact test. The effect of CYP3A5 polymorphism on changes in tacrolimus exposure after the conversion to once-daily formulation was tested during the analysis of covariance (ANCOVA).