Comparison of postoperative analgesic effects of posterior quadratus lumborum block and intrathecal morphine in laparoscopic donor hepatectomy: in reply

We thank Cai et al for their comments on our study. We performed our study to evaluate the analgesic efficacy of quadratus lumborum block (QLB) or intrathecal morphine (ITM) as part of a multimodal analgesic regimen. In our institution, postoperative pain management in the surgical ward is usually conducted by the surgical team, and we agree that postoperative pain management needs to be refined, and thus, we regularly discuss with the surgical team to improve patient recovery. Most patients in both groups had moderate to high abdominal pain or discomfort at the time of postoperative care unit (PACU) admission, as shown in figure 3 of our study, which was also consistent with our previous studies. The high pain level may reflect significant visceral pain combined with somatic pain. In addition, some patients in both groups had moderate pain at 24 hours and 48 hours after surgery because the analgesic duration might have worn off at 12 hours after QLB and at 36 hours after ITM, respectively. Second, we agree that the predetermined noninferiority margin of 1 might be small, which was already mentioned in the limitation. In our study, the predetermined noninferiority margin was set based on our previous study and review article for noninferiority analysis. Since the mean resting pain score at 24 hours is relatively low in the ITM group, we hypothesised that the noninferiority margin should also have to be low to compare QLB as an alternative to ITM. However, we disagree that the median minimal clinically significant differences for pain scores should be 1.5 at rest, since this value is usually applicable for total hip or knee arthroplasty, and not for liver surgery, especially in living donors. This should be elucidated in future studies. I appreciate your interest in our research.