Spss software package for windows version 15

Statistical analysis was performed using SPSS software package for Windows, version 15.0 (SPSS Inc., Chicago, IL, USA). Categorical variables were compared across both the groups using Fischer’s exact test or Chi-square test, as appropriate for the data. The continuous variables were analyzed as mean ± standard deviation and were compared using Student t test or Mann–Whitney U test, as appropriate. Tests for normal distribution were performed using Shapiro–Wilk test.
We also explored the possibility of operator learning curve in the d-TRA group in terms of the primary end point and AT. For this purpose, the d-TRA patients were divided into four groups of 25 consecutive cases each. A one-way analysis of variance was used to compare the mean AT among the four groups. Multivariate analysis was performed to assess any confounding effect of demographic variables and comorbidities on the success of procedure or on obtaining access. A p value of <0.05 was considered statistically significant throughout the analysis.

Statistical analysis was performed with the SPSS software package for Windows version 15.0 (SPSS Inc., Chicago, IL, USA) and R Statistical Software version 3.5.1 (The R foundation for statistical computing). All categorical variables were expressed as percentages, and all continuous variables, as mean ± SD. The differences between categorical variables were analyzed by Chi-squared and McNemar's tests. Dyssynchrony indices were summarized using median and the 25th and 75th percentiles because they were not normally distributed. Comparisons among the four groups were performed using the Kruskal–Wallis test, followed by Dunn's test to correct for multiple comparisons, and the Bonferroni correction was applied for the adjustment of the significance level. The intraobserver reproducibility was evaluated using the Pearson correlation coefficient, and Bland–Altman plots were generated to assess the agreement between modalities. The mean difference and limits of agreement (±1.96 SD) of the Bland–Altman plots were used as reference of agreement. For all the analyses, P value <0.05 was considered statistically significant.