Variable Multivariate p-value Odds Ratio 95% Confidence Interval Intervention (placebo versus clonidine) 0.007 2.278 1.239 4.189 Gender (male versus female) 0.495 0.869 0.581 1.300 Advanced age 0.824 0.939 0.541 1.631 Weight 0.894 0.972 0.642 1.472 Baseline heart rate 0.007 1.800 1.173 2.763 Baseline mean arterial pressure 0.054 0.667 0.441 1.008

Table 2: Difference in cough appearance after fentanyl injection between the groups received clonidine and placebo in a multivariable logistic regression model.