The effect of intraoperative midazolam on postoperative delirium in older surgical patients: a prospective, multicentre cohort study

Background Midazolam is a short-acting benzodiazepine frequently used in the perioperative setting. This study aimed to investigate the potential impact of intraoperative midazolam on postoperative delirium (POD) in older patients undergoing non-cardiac surgery. Methods This study included patients aged ≥ 65 years who received general anaesthesia between April 2020 and April 2022 in multiple hospitals across China. POD occurring within 7 days was assessed using the 3-minute Diagnostic Interview for Confusion Assessment Method (3D-CAM). Univariable and multivariable logistic regression models based on the random effects were used to determine the association between midazolam administration and the occurrence of POD, presented as risk ratio (RR) and 95% confidence intervals (CI). Kaplan–Meier cumulative incidence curve was plotted to compare the distribution of time to POD onset between patients who received midazolam and those who did not. Subgroup analyses based on specific populations were performed to explore the relationship between midazolam and POD. Results In all, 5,663 patients were included, of whom 723 (12.8%) developed POD. Univariate and multivariable logistic regression analyses based on random effects of different hospitals showed no significant association between midazolam medication and POD among older population (unadjusted RR=0.96, 95% CI: 0.90–1.30, P=0.38; adjusted RR=1.09, 95% CI: 0.91–1.33, P=0.35). Kaplan–Meier curve showed no difference in the distribution of time to POD onset (Hazard ratio [HR]=1.02, 95%CI: 0.88-1.18, P=0.82). The results of subgroup analyses found that intraoperative midazolam treatment was not associated with POD in the specific subgroups of patients. Conclusions Intraoperative administration of midazolam may not be associated with an increased risk of POD in older patients undergoing non-cardiac surgery.