Remimazolam tosylate or propofol and delirium in frail elderly patients after hip surgery

BACKGROUND: Remimazolam tosylate, a novel short-acting benzodiazepine, is increasingly being used in general anaesthesia, but its role in the incidence of postoperative delirium is uncertain, particularly in frail elderly patients. OBJECTIVE: To compare the effects of remimazolam tosylate with propofol on the incidence of postoperative delirium in frail elderly patients undergoing hip surgery. DESIGN: Randomised, single-centre, single-blind controlled trial. SETTING: A tertiary teaching hospital in China, conducted from March to December 2023. PATIENTS: Frail elderly patients (Reported Edmonton Frail Scale Score ≥ 6) undergoing hip surgery under general anaesthesia. INTERVENTIONS: Patients were randomly assigned to either the propofol or remimazolam group. Both groups received total intravenous anaesthesia following a standardised protocol with either propofol or remimazolam tosylate for induction and maintenance. MAIN OUTCOME MEASURES: The primary outcome was the incidence of postoperative delirium within three postoperative days, assessed twice daily using the 3D Confusion Assessment Method (3D-CAM). The secondary outcomes included the quality of postoperative recovery and adverse events. RESULT: A total of 136 patients were enrolled. The incidence of postoperative delirium was significantly lower in the remimazolam group than in the propofol group [3 of 68 (4.4%) vs. 12 of 68 (17.6%), risk differece (RD) -13.2%, 95% CI -23.5% to -2.9%, relative risk (RR) 0.25, 95% CI 0.074 to 0.847, NNT 7.6, P = 0.0143]. The incidence of hypotension after induction was also lower in the remimazolam group [16 of 68 (23.5%) vs. 32 of 68 (47.1%), RD -23.5%, 95%CI -39.1% to -8.0%, RR 0.5, 95% CI 0.304 to 0.822, NNT 4.3, P = 0.004], with fewer patients requiring vasopressors [55 of 68 (80.9%) vs. 66 of 68 (97.1%), RD -16.2%, 95% CI -26.3 to -6.0, RR 0.8, 95% CI 0.737 to 0.942, NNT 6.2, P = 0.003]. Notably, the remimazolam group exhibited significantly less burst suppression compared with the propofol group, both in terms of burst suppression time (2.2 s [0 to 17.6] vs. 21.9 s [2.3 to 115.3] median difference = 11.98 s, 95% CI 2.44 to 27.90, P < 0.001) and its proportion relative to the total surgery time (0.3‰ [0 to 2.1] vs. 2.8‰ [0.2 to 14.7], median difference 1.30‰, 95% CI 0.27 to 3.34, P < 0.001). CONCLUSION: In frail elderly patients, remimazolam tosylate was associated with a lower incidence of postoperative delirium compared with propofol. TRIAL REGISTRATION: Chinese Clinical Trial Registry, Chictr.org.cn, identifier: ChiCTR2300068632.