Intraoperative blood transfusion predicts postoperative delirium among older patients undergoing elective orthopedic surgery: A prospective cohort study

Objectives: To evaluate the roles of preoperative anemia and intraoperative blood transfusion in the development of postoperative delirium among older patients undergoing elective orthopedic surgery. Methods: This prospective cohort study recruited subjects aged 60 years old and above who were admitted for elective orthopedic surgery in a tertiary medical center during April 2011 to December 2013. Demographic data (age, gender, body mass index [BMI], and educational level), surgery-related factors (American Society of Anesthesiology [ASA] class, type of anesthesia and surgery, and intraoperative blood transfusion), results of geriatric assessment (hearing/visual impairment, cognition, depressive mood, comorbidity, malnutrition, polypharmacy, activities of daily living [ADL], and instrumental activities of daily living [IADL]), laboratory data, length of hospital stay, and the development of postoperative delirium were collected for analysis. Results: Overall, 461 patients (mean age: 73.5 ± 7.5 years, 42.1% males) were enrolled for study, and 37 (8.0%) of them developed postoperative delirium. We categorized all subjects into four groups based on anemia on admission and blood transfusion during operation or not. Multivariate logistic regression showed that subjects with anemia on admission and received intraoperative blood transfusion were at higher risk of developing postoperative delirium (adjusted odds ratio 3.090; 95% confidence interval [CI], 1.070-8.926) and those without anemia on admission but received intraoperative blood transfusion were at marginal risk (adjusted odds ratio 2.906; 95% CI, 0.912-9.259) after adjustment for covariates. Conclusions: Anemic older patients receiving intraoperative blood transfusion during operation were at the greatest risk for postoperative delirium when they underwent elective orthopedic surgery. Further intervention study is needed to reduce the risk of postoperative delirium for these patients.