Primary outcome
The anesthesia success rate was 92.3% in the MISB group and 94.6% in the LISB group. The mean difference in the anesthesia success rate between the two groups was –2.3%, with a 95% confidence interval (CI) of –13.4% to 8.8%. With the non-inferiority margin set at − 15%, MISB was confirmed to provide a non-inferior anesthesia effect compared to LISB. (Fig. Mean difference in the anesthesia success rate. A non-inferiority test for the difference between two proportions was performed to determine the differences between MISB and LISB. The black line at the mean difference − 15% indicates the non-inferiority margin. The region to the right of the black line indicates non-inferiority, the region to the left of the black line indicates inferiority, and the region to the right of the dotted line indicated superiority. CI, confidence interval