Comment on “Ultrasound-guided subtransverse interligamentary (STIL) block versus erector spinae plane (ESP) block for postoperative analgesia in patients undergoing modified radical mastectomy (MRM)”

Dear Editor, By conducting a randomised, controlled clinical trial in a total of 120 female participants who underwent modified radical mastectomy, Anand et al.[1] showed that the subtransverse interligamentary block (STILB) compared with the erector spinae plane block (ESPB) provided an improved postoperative pain control and a decreased number of rescue tramadol. However, certain issues need further discussion and clarification. First, Anand et al.[1] did not provide the details regarding preoperative pain severity, psychological and sleep disorders, use of chemoradiotherapy, extents and types of surgery, and postoperative complications. Available literatures indicate that preoperative sleep disorders, anxiety, depression, pain catastrophizing scores, chemotherapy, axillary dissection, the number of axillary lymph node resections, and postoperative urinary and gastrointestinal complications are significantly associated with an increased severity of acute pain after breast cancer surgery. In contrast, preoperative radiotherapy is associated with a reduced severity of postoperative acute pain.[2,3] Any significant between group difference in these unknown preoperative factors would have biased the main findings of this study. Second, Anand et al.[1] did not clearly describe the participants’ status when evaluating postoperative pain intensity, albeit postoperative pain intensity is more severe during movement than at rest in participants undergoing radical mastectomy.[4] Furthermore, rescue analgesic ketorolac, a potent nonsteroidal anti-inflammatory drug suitable for moderate to severe acute postoperative pain control, was intravenously given at 0.5 mg/kg twice daily during the first 48 h. That is, administration times of ketorolac exactly coincided with the time points of pain assessment at 12 h and 24 h postoperatively. However, the time relations of ketorolac administration with pain assessments at 12 h and 24 h postoperatively were unclear. We argue that these unknown factors would have confused the results of postoperative acute pain assessment. Third, Anand et al.[1] did not convert total dosages of tramadol within 24 h postoperatively into morphine milligram equivalents. Thus, it was unclear if the between-group difference in the morphine milligram equivalents of total tramadol consumption was statistically significant and exceeded the minimal clinically important difference recommended in available literature, that is, 9 mg intravenous morphine.[5] The between-group difference of postoperative opioid consumption may be clinically unimportant. Finally, the main purposes of adding regional blocks to the postoperative analgesia scheme are to enhance functional recovery and improve patients’ outcomes.[5] However, Anand et al.[1] did not assess the important outcome variables of the current enhanced recovery after breast surgery practices, such as the times to first ambulation and first flatus, quality of postoperative recovery, patient satisfaction with postoperative pain control, occurrence of nausea and vomiting, overall complication rate, length of stay, and others.[6] Due to this limitation, an important question that this study cannot answer is whether improved postoperative analgesia by the STILB compared with the ESPB may transform the real clinical benefits of patients undergoing radical mastectomy. This deserves further research. Declaration of Patient consent As this is a letter to the editor that comments the published paper in Indian Journal of Anaesthesia and is not involved in any human study, the IRB approval, consent statement and clinical trial registration are not applicable. Presentation at conferences/CMEs and abstract publication No. Study data availability No datasets were generated or analysed during the current study. Disclosure of use of artificial intelligence (AI)-assistive or generative tools The AI tools or language models (LLMs) have not been utilised in the manuscript, except that software has been used for grammar corrections. Declaration of use of permitted tools Not applicable Authors contributions YBL: Concepts, design, definition of intellectual content, literature search, data analyses, manuscript preparation, and approval. DFW: Concepts, design, data analyses, manuscript editing, review and approval FSX: Concepts, design, data analyses, manuscript editing, review and approval. Supplementary material This article has no supplementary material. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.