Statistical analysis
The primary outcome was a reduction of QUIP-RS score between baseline and 8 weeks. We defined a success as a reduction by 3 points or more between baseline and 8 weeks of the highest QUIP-RS subscore at baseline, without any augmentation in the other QUIP-RS dimension. The minimal clinical difference was set at a 15% difference of success between placebo and clonidine. Using a confidence interval (CI) approach [