BACKGROUND CONTEXT: As the population ages and surgical techniques improve, more elderly patients with dementia are being considered for treatment of spinal disorders. However, the combined impact of procedural intensity and anesthesia exposure can exacerbate surgical risks, leading to more complex recoveries and postoperative morbidity. PURPOSE: To compare postsurgical outcomes of patients living with dementia who received elective lumbar spine surgery with a comparable group of patients without dementia. STUDY DESIGN/SETTING: Retrospective analysis using national Medicare claims. PATIENT SAMPLE: We identified Medicare beneficiaries living with dementia who underwent elective lumbar spine surgery between 2017 and 2018. This cohort was compared to Medicare beneficiaries who received comparable surgeries but without a diagnosis of dementia. OUTCOME MEASURES: The primary outcome was any adverse event (AAE) within 180 days of surgery, with postoperative intensive interventions considered in parallel with other clinical outcomes. METHODS: We employed inverse probability of treatment weights to adjust for confounding. We compared outcomes between cohorts using adjusted hazard ratios (aHR) from Cox-proportional hazard models and Fine-and-gray models considering death as a competing risk. RESULTS: We included 101,313 patients. Within 180 days of surgery, patients with dementia had an increased hazard of AAE than those without dementia (aHR 1.30
95% CI 1.21,1.40). Patients with dementia also demonstrated a greater hazard of mortality (aHR 1.75, 95%CI 1.33, 2.29) and postoperative intensive interventions (aHR 1.64, 95% CI 1.08, 2.49) over the same time frame. CONCLUSIONS: We found a significantly increased risk of adverse events among patients living with dementia undergoing lumbar spine surgery. We believe these risks were previously underappreciated because of the focus on urgent procedures (e.g., hip and odontoid fractures) in prior research evaluating postoperative outcomes for patients with dementia. Our results suggest the need for greater caution when recommending elective, high-intensity, surgical interventions for patients living with dementia.