Spss statistics software ver 21

Data analyses were performed using IBM SPSS Statistics software (ver. 21.0; IBM, USA). The measurement data are expressed as the mean ± SD and conformed to a normal distribution and homogeneity of variance. The unpaired t-test was selected for comparisons between two groups, and one-way ANOVA was used for comparisons of multiple groups, followed by Tukey’s post-hoc test. The data at different time points were analyzed using repeated-measures ANOVA, and Bonferroni’s test was performed for post hoc tests. Statistical significance was confirmed at P < 0.05.

IBM SPSS Statistics software ver. 21.0 (IBM Co., Armonk, NY, USA) was used for statistical analysis of the data. Categorical variables were analyzed using a chi-square test and continuous variables were analyzed using a two-sample t-test. Variables with a p-value of less than 0.1 in univariate analysis were included in a multivariate analysis. Survival analysis was performed using the Kaplan-Meier log-rank method.

Postoperatively, patients were evaluated by a member of the surgical team at least twice a day. Any deviation from the normal postoperative course was considered a complication. Postoperative morbidity and mortality accounted for all adverse events occurring in-hospital or within 30 days after surgery. Complications were graded according to the Clavien-Dindo classification [15 (link)].
All demographics, clinical and outcome data were prospectively collected and stored in a dataset of personal computer. Continuous data were analyzed with the Student t-test or the Kruskal-Wallis test as appropriate. Categorical data were compared using the chi-square test or Fisher exact test. Continuous data were presented as means± standard deviations, or medians (ranges). Categorical data were presented as frequencies. A P-value of < 0.05 was considered statistically significant. Statistical analysis was performed using IBM SPSS Statistics software ver. 21.0 (IBM Corp., Armonk, NY, USA).