2.9. Power and Sample Size
Based on the same surgical population (200 cases) in our institution, a power analysis was performed using the frequencies of adjustment of propofol and remifentanil doses during surgery as the primary variables, where the mean and SD of adjustment times were set to 3.0 and 1.1, respectively. A power analysis indicated that at least 42 patients were required in each group to detect a difference of 0.6 points in the VAS score (20% of the non-inferiority margin selected for clinical consideration), with a type I error of 0.05 and a power of 80%. With an estimated 10% dropout rate, we enrolled 92 patients. Ultimately, 84 patients were included for analysis.