Incidence & Risk Factors of Postoperative Delirium After Spinal Surgery in Older Patients

Although postoperative delirium is a common complication in older patients, few papers have described risk factors after of spinal surgery. The purpose of this study was to analyze various perioperative risk factors for delirium after spinal surgery in older patients. This study was performed on retrospective data collection with prospective design. We analyzed 138 patients over 65 years of age who underwent spinal surgery. Preoperative factors were cognitive function (Mini-Mental State Examination-Korean (MMSE-K) and the Korean version of the Delirium Rating Scale-Revised-98 (K-DRS 98)), age, sex, type of admission, American Society of Anesthesiologist classification, metabolic equivalents, laboratory findings, visual analog scale, and Oswestry Disability Index. Intraoperative factors were operation time, blood loss, and type of procedure. Postoperative factors were blood transfusion and type of postoperative pain control. Postoperative delirium developed in 25 patients (18.16%). Patients were divided into two groups: Group with delirium (group A) and group without delirium (group B). MMSE-K scores in Group A were significantly lower than in Group B (p<0.001). K-DRS 98 scores were significantly higher in Group A than Group B (p<0.001). The operation time was longer in Group A than Group B (p=0.059). On multivariate regression analysis, the odds ratio of K-DRS 98 was 2.43 (p=0.010). After correction for the interaction between age and MMSE-K, patients younger than 73 years old had a significantly lower incidence of delirium with higher MMSE-K score (p=0.0014). Older age, low level of preoperative cognitive function, long duration of surgery, and transfusion were important risk factors of postoperative delirium after spinal surgery. It is important to recognize perioperative risk factors and manage appropriately.