Statistical analysis
Continuous variables were tested for normality with the
Kolmogorov-Smirnov and Shapiro Wilk tests. The values are expressed
either as mean ± standard deviation (SD) or median, and 25 and 75
percentiles. The categorical data are presented as absolute values and
percentages and were tested using Pearson χ2 test and Fischer’s Exact
Test. The comparison between groups was performed using the Kruskal
Wallis test or Pearson χ2 test and Fischer’s Exact Test, as appropriate.
Event-free survival and patient survival analysis was conducted
according to the Kaplan-Meier product-limit estimates, and patient
subgroups were compared using a two-sided log-rank test.
A Cox-Regression analysis was conducted to evaluate the association of
each clinically or statistically significant (p<0.1) variable
with the outcome (event-free survival).
A scoring system was derived from the Cox-Regression analysis to predict
the outcome probability (recurrence/death) according to the number of
factors presented by the patient in the pre-transplant period.
The area under the receiver operating characteristic curve (AUC ROC) was
the tool used to evaluate the association of AFP reduction with the
outcome (event-free survival). Therefore, AUC ROC ranges from 0 to 1,
with 1 corresponding to a perfect score. AUC ROC ≤ 0.7 are considered to
have very little predictive ability. The level of statistical
significance adopted was P ≤ 0.05. All analyses were performed using the
SPSS 21.0 statistical package (IBM, Inc., Chicago, IL, USA).