Effect of Perioperative Tricyclic Antidepressants and First-Generation Antihistamines on Postoperative Delirium in Older Patients Undergoing Arthroplasty or Spine Surgery.

Background Postoperative delirium (POD) is a prevalent condition in older surgical patients, leading to extended hospital stays and increased risk of cognitive and functional decline. We investigated whether in-hospital perioperative administration of tricyclic antidepressants (TCAs) or first-generation antihistamines, both of which have potent anticholinergic activity, was associated with postoperative delirium within the first three postoperative days in older surgical patients undergoing major arthroplasty or spine surgeries. Methods We undertook a secondary data analysis of patients aged 65 or older staying in the hospital for at least two days undergoing hip, knee, or spine surgeries from two prospective studies. Using propensity score matching applied separately for each medication class (TCAs and first-generation antihistamines) to respective control groups. Our primary outcome was the incidence of postoperative delirium within the first three postoperative days, as gauged by the Confusion Assessment Method. Results After propensity score matching, which was applied separately for each medication class, no difference in demographics, geriatric depression scores, cognitive status scores, or surgical details emerged between the medication recipients and non-recipients. The perioperative use of tricyclic antidepressants (OR: 1.82, 95% CI: 0.78-4.16) or first-generation antihistamines (OR: 0.79, 95% CI: 0.48-1.28) was not statistically significantly associated with postoperative delirium. Conclusion In this secondary analysis of older patients undergoing elective major arthroplasty or spine surgery, we did not detect a statistically significant association between perioperative tricyclic antidepressant or first-generation antihistamine use and postoperative delirium within the first three postoperative days. These findings should be interpreted cautiously, given the limited sample size for TCA exposure.