Risk factors for delirium in elderly patients after lumbar spinal fusion.

OBJECTIVE: To identify perioperative risk factors for postoperative delirium (POD) in patients aged 65 or older undergoing lumbar spinal fusion procedures. PATIENTS AND METHODS: A retrospective cohort analysis was performed on patients undergoing lumbar spinal fusion over an approximately three-year period at a single institution. Demographic and perioperative data were obtained from electronic medical records. The primary outcome was the presence of postoperative delirium assayed by the Delirium Observation Screening Scale (DOSS) and Confusion Assessment Method for the ICU (CAM-ICU). Univariate and multivariate analyses were performed on the data. RESULTS: Of the 702 patients included in the study, 173 (24.6%) developed POD. Our analysis revealed that older age (p < 0.001), lower preoperative hemoglobin (p < 0.001), and higher ASA status (p < 0.001), were significant preoperative risk factors for developing POD. The only significant intraoperative risk factor was a higher number of spinal levels that were instrumented (p < 0.001). Higher pain scores on postoperative day 1 (p < 0.001), and lower postoperative hemoglobin (p < 0.001) were associated with increased POD; as were ICU admission (p < 0.001) and increased length of ICU stay (p < 0.001). Patients who developed POD had a longer hospital stay (p < 0.001) with lower rates of discharge to home as opposed to an inpatient facility (p < 0.001). CONCLUSION: Risk factors for POD in older adults undergoing lumbar spinal fusion surgery include advanced age, diabetes, lower preoperative and postoperative hemoglobin, higher ASA grade, greater extent of surgery, and higher postoperative pain scores. Patients with delirium had a higher incidence of postoperative ICU admission, increased length of stay, decreased likelihood of discharge to home and increased mortality, all consistent with prior studies. Further studies may determine whether adequate management of anemia and pain lead to a reduction in the incidence of postoperative delirium in these patients.