JBJS - 2026-04-15 - Journal Article
Low Cognitive Function and Somatic Psychological Symptoms Are Correlated with Greater Risk of Delirium After Total Knee Arthroplasty: A Prospective Cohort Study.
Lee JY, Park JE, Kim SE, Choi BS, Lee MC, Chang CB, Han HS, Park HY, Ro DH
Topics
Key Takeaway
In 574 TKA patients ≥60 years, preoperative MMSE ≤25 (OR 0.771) and elevated PHQ-15 somatic symptom score (OR 1.187) were independent predictors of postoperative delirium, which occurred in 4.2% of the cohort.
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Summary
This prospective cohort study evaluated whether preoperative cognitive and psychological screening tools predict postoperative delirium (POD) in patients ≥60 undergoing primary TKA at two tertiary centers. POD occurred in 4.2% (24/574); multivariable logistic regression identified MMSE score (OR 0.771 per point, p=0.002) and PHQ-15 somatic symptom score (OR 1.187 per point, p=0.028) as independent predictors. An MMSE cutoff of ≤25 yielded AUC 0.834 with 74.5% sensitivity and 78.3% specificity for POD prediction.
Key Limitation
With only 24 POD events, the multivariable logistic regression model is underpowered and at risk of overfitting, limiting confidence in the independent effect sizes reported for MMSE and PHQ-15.
Original Abstract
BACKGROUND
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.
METHODS
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.
RESULTS
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.
CONCLUSIONS
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.
LEVEL OF EVIDENCE
Prognostic Level II . See Instructions for Authors for a complete description of levels of evidence.