Frailty is an important predictor of 30-day morbidity in patients treated for lumbar spondylolisthesis using a posterior surgical approach.

<bold>Background Context: </bold>Traditionally, a nonoperative approach has been favored for elderly patients with lumbar spondylolisthesis due to a perceived higher risk of morbidity with surgery. However, most studies have used an arbitrary age cut-off to define "elderly" and this research has yielded conflicting results.<bold>Purpose: </bold>The purpose of this study was to investigate the impact of frailty on morbidity after surgery for degenerative lumbar spondylolisthesis treated with a posterior approach.<bold>Study Design: </bold>A retrospective cohort study was performed.<bold>Patient Sample: </bold>The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database, with years 2010 to 2018 included in this study. Patients who received posterior lumbar spine decompression with or without single level posterior instrumented fusion for degenerative lumbar spondylolisthesis were included. Patients who received anterior and/or lateral approaches were excluded.<bold>Outcome Measures: </bold>The primary outcome was Clavien-Dindo grade IV complication. Secondary outcomes were readmission, reoperation, and discharge to location other than home.<bold>Methods: </bold>Patient demographics and comorbidities were extracted. Logistic regression analysis was performed to investigate the association between outcomes and the Modified Frailty Index-5, adjusting for age, gender, body mass index, smoking status, and surgical procedure performed. A sub-analysis was done to assess the effect of frailty in three different age groups (18-45 years, 46-65 years, and >65 years) for the two surgical cohorts.<bold>Results: </bold>There were 15,658 patients in this study. The mean age was 62.5 years. Approximately 70% of the patients received decompression with fusion. Frailty was significantly associated with an increased risk of major complication, unplanned readmission, reoperation, and non-home discharge. The risk increased with increasing frailty. For patients who received decompression, frailty was associated with a higher risk of readmission and non-home discharge in patients >65 years. For patients who received decompression and fusion, frailty was associated with a higher risk of complications, readmission, and non-home discharge in patients >65 years.<bold>Conclusions: </bold>Frailty is independently associated with a higher risk of morbidity after posterior surgery in patients with lumbar spondylolisthesis, especially in patients older than 65. These data are of significance to clinicians in planning treatment for these patients. [ABSTRACT FROM AUTHOR]