Association between the number of delirium-associated medications and postoperative delirium in older adults: a multicenter retrospective study

A variety of medications contribute to the risk of postoperative delirium (POD) in older adults. This multicenter retrospective study aimed to investigate the relationship between the number of delirium-associated medication types and the incidence of POD. Patients aged greater than or equal to 70 years who underwent surgery under general anesthesia were included. Odds ratios (ORs) and 95% confidence intervals were estimated via multivariate logistic regression analysis, using patients not receiving delirium-associated medications as the reference group. Delirium-associated medications were selected from seven medication classes: benzodiazepines, non-benzodiazepines, opioids, antiparkinsonian agents, glucocorticoids, H1-antihistamines, and H2-antihistamines. A total of 4562 patients were included in the analysis. The overall incidence of POD was 7.7% (352/4562) and increased progressively with the number of delirium-associated medication types, from 6.0% among patients receiving none to 31.0% among those receiving four or more types. After adjusting for other delirium-related factors, the ORs of POD were significantly higher in patients receiving delirium-associated medications than in those receiving none and increased with the number of medication types. Sensitivity analyses confirmed the robustness of these findings. Our findings suggest that a higher number of delirium-associated medications is associated with an increased risk of POD in older adults, warranting preoperative medication review.