Postoperative Application of Dexmedetomidine is the Optimal Strategy to Reduce the Incidence of Postoperative Delirium After Cardiac Surgery: A Network Meta-Analysis of Randomized Controlled Trials

Background: Previous pairwise meta-analyses demonstrated the efficacy and safety of dexmedetomidine in preventing postoperative delirium (POD) after cardiac surgery; however, the optimal time of applying dexmedetomidine remains unclear. Objective: This network meta-analysis aimed to determine the optimal time of using dexmedetomidine to reduce the incidence of POD following cardiac surgery. Methods: We first retrieved eligible randomized controlled trials (RCTs) from previous meta-analyses, and then an updated search was performed to identify additional RCTs in PubMed, Embase, and the Cochrane library from January 1, 2021 to October 31, 2021. Two authors screened literature, collected data, and evaluated bias risk of eligible studies. Finally, we performed Bayesian network analysis using R version 3.6.1 with the "gemtc" and "rjags" package. Results: Eighteen studies with 2636 patients were included, and all studies were identified from previous meta-analyses. Results showed that postoperative dexmedetomidine reduced the risk of POD compared with normal saline (NS) (odds ratio [OR], 0.13; 95% credible interval [CrI], 0.03-0.35) and propofol (PRO) (OR, 0.19; 95%CrI, 0.04-0.66). Postoperative dexmedetomidine was associated with a lower incidence of POD compared with perioperative dexmedetomidine (OR, 0.21; 95% CrI, 0.04-0.82). Moreover, postoperative dexmedetomidine had the highest probability of ranking best (90.98%), followed by intraoperative dexmedetomidine (46.83%), PRO (36.94%), perioperative dexmedetomidine (30.85%), and NS (60.02%). Conclusion and Relevance: Dexmedetomidine reduces the incidence of POD compared with PRO and NS in patients undergoing cardiac surgery, and postoperative application of dexmedetomidine is the optimal time.