Statistical Analysis

Based on previous literature and our pilot study, the mean ± standard deviation of the time to resolution of agitation in these agitated patients was assumed to be 18.0 ± 6.0 hours.6,24 Using a two-tailed hypothesis at an α level of 0.05, an estimated sample size of 72 cases provided 80% power in detecting a 4.5-hour difference of resolution of agitation (estimation based on our pilot study). The above sample size calculations contained an inflation rate of 15% to account for the possibility that time to resolution of agitation would not be normally distributed. Considering also a dropout rate of 10%, we included a total of 80 patients.

Continuous variables were expressed as mean and standard deviation or median and interquartile range (IQR), and two independent sample t-test or Mann–Whitney U-test was used to assess the difference between the two groups as appropriate. Categorical data were presented as frequency and percentage and compared using χ² or Fisher’s exact tests. The differences in primary and secondary outcome between the two groups and their 95% confidence intervals (CIs) were calculated and reported. Time-to-event data were calculated using Log rank tests, and Kaplan–Meier curves were plotted. Statistical tests were two-sided, and a probability P < 0.05 was considered statistically significant. All statistical evaluations were conducted using SPSS version 20.0 (IBM Corp., Armonk, NY, USA).