LAUSR

Dear editor We thank Dr. Nong He et al for their comments on our study. First, we agree that the distinction is important when designing, or interpreting the results of clinical trials. However, we disagree that the minimal clinically important difference (MCID) should dictate the effect size used in a sample size calculation for a clinical trial. The chosen effect size should be clinically or scientifically meaningful, but it need not be the MCID. In addition, the recommended MCIDs of 10 mg IV morphine reduction for 24 h is for total hip arthroplasty or total knee arthroplasty, not for liver resection.