Comments on the paper by Nielsen et al. entitled “Intraoperative S‐ketamine for the reduction of opioid consumption and pain one year after spine surgery: A randomized clinical trial of opioid‐dependent patients”
Year: 2019
Type: article
Abstract: After reading the article by Nielsen et al., entitled "Intraoperative S-ketamine for the reduction of opioid consumption and pain one year after spine surgery: A randomized clinical trial of opioid-dependent patients" we reviewed another related article published by the same author in 2017 (Nielsen et al., 2017). The two articles were based on the same clinical trial (NCT02085577) assessing the effect of intraoperative ketamine on opioid consumption and pain after spine surgery in opioid-dependent patients. In the earlier article, authors found that morphine consumption, both perioperatively and at 6 months after surgery, was reduced in the ketamine group compared with the placebo group. After another 6 months of follow-up, the researchers reported a more significant decrease of morphine consumption and improvement in labour market attachment. The authors should be commended to perform such a well-designed trial on postoperative analgesia in this particular group of patients. However, there are a few points we would like to discuss. First of all, in the previous article, the preoperative baseline data of the ketamine and placebo groups were concluded from 74 and 73 patients, respectively. In the latest article, due to different reply rates, the preoperative baseline data of the same two groups should have been concluded from the answered patients, which means 47 and 51 patients, respectively. However, the preoperative data used in the latest article were exactly the same as the previous (see table 1) (Nielsen, Fomsgaard, Nikolajsen, Dahl, & Mathiesen, 2019; Nielsen et al., 2017). It seems highly unlikely that these baseline data were exactly the same. We want to know whether it is a mistake here or a coincidence. Besides, the data by fusion technique used in the ketamine group were 41 and five for instrumented and noninstrumented, respectively, with the total number being 46, and it did not match the number of patients in the ketamine group, which was 47 (Nielsen et al., 2019). Secondly, we have some doubts about the conclusion that S-ketamine could improve labour market attachment and reduce morphine consumption. The prognosis of patients after spinal fusion depends on a variety of factors, including the severity of disease before operation, the type and effect of surgery and perioperative medication, such as ketamine studied by the authors. Although ketamine may play a role, the comparison of other factors is also important. Only when other variables between the two groups were strictly controlled, can it be concluded that the improvement of prognosis and other changes in patients were the contribution of ketamine. The authors did not describe the related factors in detail, especially the preoperative assessment of the severity of the orthopaedical situation and the evaluation of the effect of surgery, which can affect important aspects of patients, such as the improvement of postoperative pain and motor function. These aspects may then play a key role in postoperative opioid dosage and patient performance, thereby affecting the interpretation of the results of the study. Pain management and other related problems of patients with chronic opioid dependency form a clinical puzzle which requires further research. The author indeed made a valuable attempt with ketamine, but whether the conclusion is solid or not needs further consideration.
Source: European Journal of Pain
DOI: 10.1002/ejp.1394
Authors: Kai Wang, Ni An, Xin Jiang, Hongbin Yuan
Institution: Shanghai Changzheng Hospital
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2921088705