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.