Effects of dexamethasone on post-operative cognitive dysfunction and delirium in adults following general anaesthesia: a meta-analysis of randomised controlled trials.

Background: Several studies have investigated the effects of dexamethasone on post-operative cognitive dysfunction (POCD) or post-operative delirium (POD); however, their conclusions have been inconsistent. Thus, we conducted a meta-analysis to determine the effects of dexamethasone on POCD and POD in adults following general anaesthesia.
Methods: The Cochrane Central Register of Controlled Trials (2018, Issue 11 of 12) in the Cochrane Library (searched 17 November 2018), MEDLINE OvidSP (1946 to 16 November 2018) and Embase OvidSP (1974 to 16 November 2018) were searched for randomised controlled trials that evaluated the incidence of POCD and POD following dexamethasone administration in adults (age ≥ 18 years) under general anaesthesia. We used the Grading of Recommendations, Assessment, Development and Evaluations framework to assess the quality of the evidence.
Results: Five studies were included (three studies with 855 participants in the dexamethasone group and 538 participants in the placebo group for the incidence of POCD, and two studies with 410 participants in the dexamethasone group and 420 participants in the placebo group for the incidence of POD). There was no significant difference between the dexamethasone group and the placebo group in terms of the incidence of POCD 30 days after surgery (RR [relative risk] 1.00; 95% CI [confidence interval: 0.51, 1.96], P = 1.00, I ²  = 77%) or the incidence of POD (RR 0.96; 95% CI [0.68, 1.35], P = 0.80, I ²  = 0%). However, both analyses had some limitations because of limited evidence and clinical heterogeneity, and we considered the quality of the evidence for the post-operative incidence of POCD and POD to be very low.
Conclusions: This meta-analysis revealed that prophylactic dexamethasone did not reduce the incidence of POCD and POD. Trials of alternative preventive strategies for POCD and POD, as well as a better understanding of the pathophysiology of those complex syndromes, are still needed to make progress in this field.
Trial Registrationr: This study is registered with PROSPERO, 23 October 2018, number CRD42018114552. Available from  https://www.crd.york.ac.uk/PROSPERO/#recordDetails .