Effect of Dementia on Risk Factors for Postoperative Delirium in Older Patients Undergoing Total Knee Arthroplasty: A Retrospective Cohort Study Based on a Large National Dataset.

Abstract

Postoperative delirium (POD) is a frequent and serious complication following total knee arthroplasty (TKA), particularly among older patients. Dementia is a well-established risk factor for POD. Whether dementia modulates the significance of other POD risk factors remains unclear. This retrospective cohort study was conducted using a large national dataset (from 2021 to 2023). Patients aged ≥ 75 years undergoing primary or revision TKA were included. Logistic regressions, adjusted for demographic, clinical, and perioperative variables, were performed to assess the association between dementia and POD risk. Separate multivariate models were used for patients who did and did not have dementia. This study cohort comprised 22,077 patients. Among them, 609 patients (2.8%) had dementia. The POD incidence rate was significantly higher in patients who had dementia (20.7 versus 2.6%). Dementia was independently associated with POD (adjusted odds ratio: 6.47; 95% confidence interval: 5.13 to 8.15). In patients who had dementia, advanced age, smoking, and functional dependency were the strongest POD predictors. In patients who did not have dementia, advanced age, functional dependency, a history of falls, a higher American Society of Anesthesiologists class, and anemia were significant predictors. General anesthesia was not associated with increased POD risk in either group. Dementia is a strong and independent predictor of POD after TKA. It modulates the significance of other risk factors. Falls, anemia, and a higher ASA class may indicate undiagnosed cognitive impairment in patients who did not have dementia. Preoperative cognitive screening among high-risk patients, combined with multidisciplinary preventive strategies, may improve surgical outcomes and optimize resource allocation.