Preoperative Cognitive Impairment and Postoperative Delirium in Elderly Surgical Patients

Objective: To test the hypothesis that in surgical patients ≥70 years, preoperative cognitive impairment is independently associated with postoperative delirium. Background: Postoperative delirium is common among elderly surgical patients and is associated with longer hospitalization and significant morbidity. Some evidence suggest that baseline cognitive impairment is an important risk factor. Routine screening for both preoperative cognitive impairment and postoperative delirium is recommended for older surgical patients. As of 2019, we implemented such routine perioperative screening in all elective surgical patients ≥70 years. Methods: Retrospective single-center analysis of prospectively collected data between January and December 2020. All elective noncardiac surgical patients ≥70 years without pre-existing dementia were included. Postoperative delirium, defined as 4A’s test score ≥4, was evaluated in the postanesthesia care unit and during the initial 2 postoperative days. Patients’ electronic records were also reviewed for delirium symptoms and other adverse outcomes. Results: Of 1518 eligible patients, 1338 (88%) were screened preoperatively [mean (SD) age 77 (6) years], of whom 21% (n=279) had cognitive impairment (Mini-Cog score ≤2). Postoperative delirium occurred in 15% (199/1338). Patients with cognitive impairment had more postoperative delirium [30% vs. 11%, adjusted odds ratio (95% confidence interval) 3.3 (2.3–4.7)]. They also had a higher incidence of a composite of postoperative complications [20% vs. 12%, adjusted odds ratio: 1.8 (1.2–2.5)], and median 1-day longer hospital stay [median (interquartile range): 6 (3,12) vs. 5 (3,9) days]. Conclusions: One-fifth of elective surgical patients ≥70 years present to surgery with preoperative cognitive impairment. These patients are at increased risk of postoperative delirium and major adverse outcomes.