Perioperative dexmedetomidine reduces delirium in elderly patients after non-cardiac surgery: a systematic review and meta-analysis of randomized-controlled trials

Abstract

Background: Delirium is a frequent postoperative complication in elderly patients after non-cardiac surgery. We performed this updated meta-analysis to ascertain more precisely the efficacy of dexmedetomidine (DEX) on the incidence of postoperative delirium (POD) in elderly patients after non-cardiac surgery. Methods: We searched PubMed, EMBASE, the Cochrane Library, Web of Science, and the Cumulative Index of Nursing and Allied Health Literature (CINAHL) from inception until February 24, 2019. In this meta-analysis, we included randomized-controlled trials comparing the effect of DEX vs normal saline (NS) or other anesthetic drugs on POD incidence in elderly (either ≥ 60 or ≥ 65 yr old) patients undergoing non-cardiac surgery. We performed subgroup analyses of the DEX dosing strategy (starting time, dose, and duration of administration, with or without loading dose) and the strategy of various control drugs. A random-effects model was used for all analyses. Results: We included 11 studies involving 2,890 patients in our meta-analysis. The pooled results of these studies revealed that DEX significantly reduced the incidence of POD (relative risk [RR], 0.47; 95% confidence interval [CI], 0.38 to 0.58; P < 0.001) compared with the control group. Meanwhile, the incidences of hypotension (RR, 1.20; 95% CI, 1.04 to 1.39; P = 0.01) and bradycardia (RR, 1.33; 95% CI, 1.08 to 1.63; P = 0.007) were increased in the DEX group. Subgroup analyses revealed a decrease in POD incidence when DEX was administered intraoperatively (RR, 0.43; 95% CI, 0.33 to 0.57; P < 0.001) and postoperatively (RR, 0.38; 95% CI, 0.27 to 0.54; P < 0.001) with a loading dose (RR, 0.49; 95% CI, 0.36 to 0.69; P < 0.001) compared with NS (RR, 0.49; 95% CI, 0.37 to 0.64; P < 0.001) and other anesthetic drugs (RR, 0.40; 95% CI, 0.26 to 0.60; P < 0.001). There were significant differences in the time to extubation (standardized mean difference, -0.60; 95% CI, -1.17 to -0.03; P = 0.04) and the length of hospital stay (mean difference, -0.50 days; 95% CI, -0.97 to -0.03; P = 0.04). The amount of data for the duration of mechanical ventilation and length of intensive care unit stay were insufficient to perform a meta-analysis. Conclusion: Perioperative dexmedetomidine reduces the incidence of POD in elderly patients after non-cardiac surgery, but this comes at the cost of an increased incidence of hypotension and bradycardia.