Sample size and statistical analysis
SECONDARY
A previously performed pilot study of 10 patients revealed the maximum NRS score when positioning for spinal anesthesia to be 4.2 ± 1.30 vs. 3 ± 1.22 in the control and PENG groups, respectively. This data was utilized using an alpha 5%, beta 10% and power of 95% to calculate a minimum sample size of 29 patients per group. Taking into consideration possible drop outs, loss to follow up and secondary outcomes, the decision was taken to have each group include 42 patients.Statistical evaluation of data was conducted with SPSS for Windows, Version 16.0. (SPSS Inc, Chicago, USA). Normal distribution was evaluated through the Kolmogorov-Smirnov test. Continuous variables were expressed as mean ± standard deviation, and median (25th–75th percentiles). Continuous variables of equal variance were analyzed using the t-test and non-normally distributed data with the Mann Whitney U test. Chi-square was used for comparison of ratios and categorical data was compared using Fisher’s exact test. Finally, Kaplan-Meier analysis and Wilcoxon test was used when comparing time to first analgesia requirement. p < 0.05 was accepted as being statistically significant in all data except for postoperative NRS scores, where after Bonferroni correction statistical significance was considered when p < 0.01.