LAUSR

We read with great interest the paper titled ‘Bolus administration of intravenous lidocaine reduces pain after an elective caesarean section: Findings from a randomised, double-blind, placebo-controlled trial’ by Gholipour Baradari et al. (2017) that was published in your esteemed journal. We have some comments on the study methods that need clarification for proper evaluation of the study results. The authors reported that they only included patients who underwent an elective caesarean section (CS) under general anaesthesia. All guidelines stress that any woman scheduled for elective CS should be offered regional anaesthesia because it is safer and results in less maternal and neonatal morbidity than general anaesthesia (Fyneface-Ogan, 2012). I wonder why the authors used general anaesthesia in their study. In the postoperative follow-up, the authors reported that women were administered a 100mg diclofenac suppository when they reported a pain score >3 cm on the visual analogue scale (VAS); and morphine 3mg each time when they reported a VAS score >5 cm. We could not estimate the frequency of use of both drugs according to the previous statement. Did the authors administer morphine for example every 2 h if the scores were repeatedly >5 cm? We think that the authors should report the frequency of use of both analgesics in their results. The authors calculated the sample size of the study based on detecting a difference of 1 in the mean VAS scores at 24 h post-operation. They did not provide any citation for the basis of sample size calculation. A clinically significant difference in VAS pain score has been defined as 1.3–2.0 cm (Todd et al. 1996; Rowbotham 2001). Therefore, a difference of 1 cm is not clinically significant. This means actually that the difference in pain scores between lidocaine and placebo groups reported in their results has no clinical significance in spite of the statistical significant difference. The authors stated that Mann–Whitney U test was used for comparing morphine and diclofenac consumption between the two groups as the data were not normally distributed. However, they were presented the data in the results as mean (standard deviation) not as median (interquartile range) as it should be. Moreover, the p value was reported by Student t-test (p1⁄4 .345). Finally, the authors stated that one of the aims of the study was to evaluate the effect of lidocaine on newborns, including the Apgar score. However, no report on this outcome was in the study results. Additionally, the level of satisfaction was not truly reported. They only asked the women if they were satisfied or not. The satisfaction level is either measured with a VAS-like scale (expressed from 0 to 10 cm) or with a five point Likert-type scale.