Lumbar spine surgeries: Ultrasound-guided erector spinae plane block versus thoracolumbar interfascial plane block

Dear Editor, I read an interesting article, ‘Comparison of efficacy of ultrasound-guided erector spinae plane (ESP) block versus thoracolumbar interfascial plane (TLIP) block in patients undergoing lumbar spine surgeries: A systematic review and trial sequential meta-analysis’.[1] I congratulate the authors for their efforts in this published article. Information sources and publication bias with asymmetrical funnel plots were appropriate. Limitations included extrapolation of results with the inclusion of more studies. Heterogenicity should be assessed with prediction interval (PI) instead of I2.[2] Binary outcomes were reported in odds ratio (OR). The effect size of meta-analysis, particularly for randomised controlled trials, can be calculated using risk ratio (RR), which is more appropriate.[3] ORs are valid association measurements but not a good substitute for risk ratios. Precision for ORs may be less if someone wants to estimate the strength of the risk ratio in a large number of cases. Rare events carry similar risks and odds, but common events yield differences between risks and odds. The reduction in 24-hour opioid consumption achieved by the ESP block did not match with reduced side effects. It is mentioned that no significant difference was observed in side effects between the groups, though a significant difference was observed in opioid consumption. For example, tramadol is used in one of the inclusive studies, and it causes more nausea and vomiting compared to fentanyl. For rescue analgesia, different drugs were used. A total of 492 cases were mentioned correctly, but study number four had only 40 patients. TSA can strengthen the findings of meta-analyses when the studies included show relative similarity.[4] Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.