ABSTRACT
BACKGROUND: Postoperative delirium has been suggested as a significant predictor of postoperative morbidity and mortality in elderly patients. They usually have multiple comorbidities, including cardiovascular, respiratory, renal, and neurologic disease. We aimed to determine the incidence rate and modifiable risk factors of postoperative delirium following total knee arthroplasty in elderly. METHODS: We reviewed the medical records of 318 elderly patients (age >65 years) underwent unilateral total knee arthroplasty between 2009 and 2016. Patient demographics, American Society of Anesthesiologists physical status, preoperative comorbidities, type and duration of anesthesia and surgery, length of hospital stay, ambulation ability, frequency of intraoperative hypotension, frequency of hypothermia, whether the patient was transfused or heparinized, and perioperative laboratory results were evaluated. Univariate and multivariate logistic regression analyses were used to identify significant independent predictors of postoperative delirium. RESULTS: The incidence rate of postoperative delirium was 6% in this study. Univariate analysis showed that postoperative delirium was significantly associated with age, body mass index, general anesthesia, anesthesia time, preoperative dementia, intraoperative hypotension, preoperative hemoglobin, blood transfusion, and intraoperative hypothermia. Preoperative dementia (odds ratio [OR] = 8.80), intraoperative hypotension (OR = 1.06), and preoperative hemoglobin (OR = 0.66) were significant independent risk factors of postoperative delirium. CONCLUSIONS: Preoperative dementia is the most important risk factor of postoperative delirium. High-risk patients undergoing total knee arthroplasty should be thoroughly evaluated and their dementia should be managed preoperatively. Adequate management of preoperative hemoglobin and intraoperative hypotension might also be helpful in reducing the incidence of postoperative delirium in this population.