Spss statistical package version 22

Statistical analysis was performed with the SPSS statistical package version 22.0 (SPSS Inc., Chicago, IL, USA). Categorical data were expressed as frequency distributions and single percentages and were compared between groups using Fisher's exact test if the expected frequency was <5 or the chi-square test. Normally distributed continuous variables were expressed as the mean ± standard deviation and were compared between groups using an independent-samples t test; non-normally distributed continuous variables were expressed as median and interquartile range (IQR) and were compared between groups with the Wilcoxon rank sum test. Baseline characteristics (including demographics, concomitant diseases, preoperative cardiac status, and echocardiographic data) with p < 0.2 obtained through the univariate analysis were then entered into forward stepwise multivariate logistic regression analysis (the combined group or the alone group as independent variables and baseline variables as dependent variables) to test the independent association between grouping (concomitant mitral subvalvular procedures vs. myectomy alone) and baseline characteristics. A two-sided p-value less than 0.05 was considered statistically significant.

Clinicopathological characteristics were compared using the χ² test for categorical variables and the Mann–Whitney U test for continuous variables. For univariate analyses, the Kaplan–Meier estimator was used with the log-rank test. Recurrence-free interval (RFI) was measured from the date of surgery to the date of recurrence or death as a result of gastric cancer and was censored at the last follow-up or non-gastric-cancer-related death. Hazard ratios (HR) were estimated by univariate Cox proportional hazards regression models. In the multivariate analysis, a Cox proportional hazards regression model was fitted. All P values <0.05 were judged as statistically significant. Variables with P < 0.05 in univariate analysis were assessed in multivariate analysis. Statistical analyses were performed using the SPSS statistical package, version 22.0 (SPSS, Chicago, IL, USA).

The statistical analyses were performed with SPSS® statistical package, version 22.0 (SPSS Inc., Chicago, IL, USA) for Windows®. Qualitative variables were expressed as numbers or percentages. Continuous variables were expressed as mean  ±  SD. Normal distribution was tested by using the Skewness-Kurtosis test. Mann–Whitney U test was used to evaluate the differences of continuous variables between two groups. Z-test was used to compare the frequency between groups. Kruskall–Wallis test was used for multiple comparisons. P value  <  0.05 was considered statistically significant.

To analyze the results, we used the SPSS statistical package, version 22.0 (SPSS, Inc.). To compare the results among tested groups, we applied the unpaired samples t-test and one-way analysis of variance (ANOVA), and Dunnett's test. p < 0.05 was considered statistically significant.