Objective: The purpose of this meta-analysis is to assess the effect of dexmedetomidine on delirium in elderly surgical patients.

Data sources: The Cochrane Library, Web of Science, PubMed, EMBASE, and Google Scholar were searched (January 1, 2000, to February 4, 2020) for randomized controlled trials (RCTs). STUDY SELECTION AND

Data extraction: RCTs without language restrictions were included if delirium incidence was assessed in elderly surgical patients receiving dexmedetomidine. Intervention and basic information were extracted.

Data synthesis: 21 studies were included. Dexmedetomidine reduced delirium occurrence (risk ratio [RR] = 0.55; 95% CI = 0.45 to 0.67) in elderly surgical patients with sufficient evidence from trial sequential analysis. Dexmedetomidine did not prevent delirium incidence for cardiac surgery (RR = 0.71; 95% CI = 0.44 to 1.15) with insufficient evidence. Dexmedetomidine decreased mortality incidence (RR = 0.47; 95% CI = 0.25 to 0.89), shortened the length of intensive care unit (ICU; standard mean difference [SMD] = -0.46) and hospital stays (SMD = -0.41), and increased bradycardia incidence (RR = 1.60). RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE: This review revealed that dexmedetomidine could reduce delirium incidence for elderly noncardiac surgical patients, and the effect of dexmedetomidine on delirium for elderly cardiac surgical patients needs further studies to guide clinicians.

Conclusion: Dexmedetomidine reduced delirium incidence in elderly surgical patients. The efficacy of dexmedetomidine on delirium for elderly cardiac surgical patients warrants further studies. Furthermore, dexmedetomidine was associated with an increased bradycardia incidence, shorter length of ICU/hospital stays, and a lower incidence of mortality.