Low Cognitive Function and Somatic Psychological Symptoms Are Correlated with Greater Risk of Delirium After Total Knee Arthroplasty: A Prospective Cohort Study.

Abstract

Postoperative delirium (POD) is a clinically important complication in elderly patients undergoing total knee arthroplasty (TKA) that is associated with prolonged hospitalization, increased morbidity, and higher health-care costs. Although cognitive impairment is a known risk factor for POD, the role of comprehensive cognitive and psychological evaluation remains underexplored in patients undergoing TKA. This study aimed to evaluate the correlation of preoperative cognitive and psychological factors with POD after TKA. This prospective cohort study included 574 patients who were ≥60 years of age and underwent primary TKA at 1 of 2 major tertiary care hospitals. We assessed preoperative cognitive function using the Mini-Mental State Examination (MMSE), the full Consortium to Establish a Registry for Alzheimer's Disease (CERAD) battery, the Subjective Memory Complaints Questionnaire (SMCQ), and the Seoul Informant Report Questionnaire for Dementia (SIRQD). Psychological assessments were conducted with the Pittsburgh Sleep Quality Index (PSQI), the Patient Health Questionnaire-15 (PHQ-15), and the Hospital Anxiety and Depression Scale (HADS). POD was evaluated daily from postoperative days 1 to 5 using the 4 A's Test (4AT) and the Confusion Assessment Method (CAM). A multivariable logistic regression analysis was performed to identify independent risk factors for POD. POD occurred in 24 (4.2%) of 574 patients. Univariate analysis revealed that POD was significantly correlated with lower MMSE (p < 0.001), higher PHQ-15 (p = 0.014), higher PSQI (p = 0.014), and higher Charlson Comorbidity Index (p = 0.010) scores; preoperative use of sedatives (p = 0.044) and antidepressants (p = 0.027); and lower mean noise levels in the patient's hospital room (p = 0.002). In the receiver operating characteristic curve analysis, the optimal cutoff value for predicting POD was an MMSE score of ≤25, with a sensitivity of 74.5% and a specificity of 78.3% (area under the curve, 0.834; p = 0.001). Multivariable logistic regression analysis identified lower MMSE scores (odds ratio [OR], 0.771; p = 0.002) and higher PHQ-15 scores (OR, 1.187; p = 0.028) as significant independent predictors of POD. This study comprehensively evaluated preoperative cognitive function and psychological symptoms in patients undergoing TKA. Even subclinical cognitive and somatic symptoms were linked to POD, emphasizing the need for preoperative identification of high-risk patients. Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.