2.7 Statistical analysis
Data was processed using Statistical Package for Social Science (SPSS) 19.0. Continuous variables were expressed as mean ± standard deviation (SD) or median (interquartile range, IQR). Categorical variables were presented as count (percentage). The differences between groups were assessed using Student’s t-test for normally distributed continuous variables, and Mann-Whitney U tests for non-normally distributed continuous variables, as appropriate. Predefined outcomes stratified by average TAC C0, IPV or CYP3A5 genotype were analyzed by Kaplan-Meier analysis and compared using the Log-rank test. Time from transplant to DSA, CLAD or death was modeled using Cox proportional hazards regression. Potential risk factors included age at transplant, sex, body mass index (BMI), comorbidities (hypertension, hyperlipidemia and diabetes), transplant-related data and TAC exposure. The variables with a P value < 0.2 in the univariate analysis were included in the multivariate analysis, which employed a forward likelihood ratio-test approach for constructing final Cox survival models. P < 0.05 was considered of statistical significance.