Effect of Intranasal Dexmedetomidine on the Night Before Surgery for Postoperative Delirium in Older Patients Undergoing Total Hip or Knee Arthroplasty: A Randomized Clinical Trial.

IMPORTANCE: Postoperative delirium is a common and serious neurocognitive complication in elderly arthroplasty patients, with preoperative poor sleep as a key risk factor. Effective preoperative prevention strategies remain an urgent clinical need. OBJECTIVE: To assess preoperative intranasal dexmedetomidine for preventing postoperative delirium in older adults undergoing hip or knee arthroplasty. DESIGN: This trial was conducted at a single tertiary academic hospital in China from January 10, 2025 to June 10, 2025, with follow-up assessments performed from admission to 7 days after surgery. SETTING: This was a single-center, double-blind, placebo-controlled randomized trial. PARTICIPANTS: 232 elderly patients aged 60 years or older, with American Society of Anesthesiologists (ASA) status 1 to 3, scheduled for total hip or knee arthroplasty under general anesthesia were enrolled and randomized 1:1 after eligibility screening. INTERVENTIONS: Intranasal dexmedetomidine(100 μg total dose) or normal saline, administered at 21:00 on the night before surgery. MAIN OUTCOMES AND MEASURES: The primary outcome was the incidence of postoperative delirium within 3 postoperative days, evaluated by the Confusion Assessment Method. Secondary outcomes included postoperative delirium incidence within 7 days, duration, severity, subtype, perioperative sleep quality, pain, anxiety, quality of recovery, time to ambulation, and adverse events. RESULTS: In the intention-to-treat analysis, the postoperative delirium incidence within 3 days was 10.3% in the dexmedetomidine group and 20.7% in the placebo group [relative risk=0.50; 95% confidence interval (CI)=0.26-0.95; P=0.030]. Intranasal dexmedetomidine could improve sleep quality and reduce preoperative and postoperative anxiety and pain. No severe adverse events or nasal mucosal injuries were observed in either group. CONCLUSION: Intranasal dexmedetomidine on the night before surgery could reduce the incidence of postoperative delirium and improve perioperative sleep quality in older patients undergoing joint arthroplasty. Sleep improvement may partly explain this association, suggesting a potential supportive strategy for delirium prevention. TRIAL REGISTRATION: Chinese Clinical Trial Registry Identifier: ChiCTR2500095414.