Background and aims The development of postoperative
chronic pain (POCP) after surgery is a major problem with a considerable socioeconomic impact. It is defined as
pain lasting more than the usual healing, often more than 2-6 months. Recent systematic reviews and meta-analyses demonstrate that the
N-methyl-D-aspartate-receptor antagonist
ketamine given peri- and intraoperatively can reduce immediate
postoperative pain, especially if severe
postoperative pain is expected and regional anaesthesia techniques are impossible. However, the results concerning the role of
ketamine in preventing
chronic postoperative pain are conflicting. The aim of this study was to perform a systematic review and a pooled analysis to determine if peri- and intraoperative
ketamine can reduce the incidence of
chronic postoperative pain. Methods Electronic searches of PubMed, EMBASE and Cochrane including data until September 2013 were conducted. Subsequently, the titles and abstracts were read, and reference lists of reviews and retrieved studies were reviewed for additional studies. Where necessary, authors were contacted to obtain raw data for statistical analysis. Papers reporting on
ketamine used in the intra- and postoperative setting with
pain measured at least 4 weeks after surgery were identified. For meta-analysis of
pain after 1, 3, 6 and 12 months, the results were summarised in a forest plot, indicating the number of patients with and without
pain in the
ketamine and the control groups. The cut-off value used for the VAS/NRS scales was 3 (range 0-10), which is a generally well-accepted value with clinical impact in view of quality of life. Results Our analysis identified ten papers for the comprehensive meta-analysis, including a total of 784 patients. Three papers, which included a total of 303 patients, reported a positive outcome concerning
persistent postsurgical pain. In the analysis, only one of nine pooled estimates of
postoperative pain at rest or in motion after 1, 3, 6 or 12 months, defined as a value ≥3 on a visual analogue scale of 0-10, indicated a marginally significant
pain reduction. Conclusions Based on the currently available data, there is currently not sufficient evidence to support a reduction in
chronic pain due to perioperative administration of
ketamine. Only the analysis of
postoperative pain at rest after 1 month resulted in a marginally significant reduction of
chronic postoperative pain using
ketamine in the perioperative setting. Implications It can be hypothesised, that regional anaesthesia in addition to the administration of perioperative
ketamine might have a preventive effect on the development of
persistent postsurgical pain. An additional high-quality
pain relief intra- and postoperatively as well after discharge could be more effective than any particular
analgesic method per se. It is an assumption that a low dose infusion
ketamine has to be administered for more than 72 h to reduce the risk of
chronic postoperative pain.