Effect of dexmedetomidine on postoperative cognitive dysfunction and inflammation in patients after general anaesthesia A PRISMA-compliant systematic review and meta-analysis

Background: Neuroprotective effects of dexmedetomidine are reported in preclinical and clinical studies but evidence regarding the postoperative neurocognitive function is still unclear. This study performed a meta-analysis on outcomes of studies which examined neurocognitive performance and inflammatory factors to investigate the effects of dexmedetomidine on postoperative cognitive dysfunction (POCD) and inflammation in patients after general anaesthesia. Methods: Literatures were searched in several electronic databases and studies were selected by following precise inclusion criteria. We searched PubMed, EMBASE, the Cochrane Library, China Academic Journals full-text database (CNKI), and Google Scholar to find randomized controlled trials (RCTs) of the influence of dexmedetomidine on POCD and inflammation in patients who had undergone general anaesthesia. Two researchers independently screened the literature, extracted data, and evaluated quality of methodology against inclusion and exclusion criteria. Meta-analyses of pooled ORs of POCD incidences and mean differences in neurocognitive assessment scores and inflammation levels were carried out and subgroup analyses were performed. Stata 12.0 was used to conduct our meta-analysis. Results: Twenty-six RCTs were included. Compared with controls, perioperative dexmedetomidine treatment significantly reduced the incidence of POCD (pooled ORs=0.59, 95% confidence interval (CI) 0.45-2.95) and improved Mini-Mental State Examination (MMSE) score (standardized mean difference (SMD)=1.74, 95% CI 0.43-3.05) on the first postoperative day. Furthermore, perioperative dexmedetomidine treatment significantly decreased IL-6 (SMD= -1.31, 95% CI -1.87-0.75, P<.001) and TNF-alpha (SMD= -2.14, 95% CI -3.14-1.14, P<.001) compared to saline/comparators treatment. In the stratified analysis by surgical type, age, type of control, and study region, the differences were also significant between dexmedetomidine- and saline-treated patients. Conclusion: Perioperative dexmedetomidine treatment is associated with significantly reduced incidence of POCD and inflammation and better neurocognitive function postoperatively in comparison with both saline controls and comparator anaesthetics.