Risk Factors for Perioperative Complications in Morbidly Obese Patients Undergoing Elective Posterior Lumbar Fusion

Study Design: Retrospective cohort study. Objectives: The prevalence of obesity-related low back pain and degenerative disc disease is on the rise. Past studies have demonstrated that obesity is associated with higher perioperative complication rates, but there remains a gap in the literature regarding additional risk factors that further predispose this already high-risk patient population to poor surgical outcomes following elective posterior lumbar fusion (PLF). The aim of the study is to identify independent risk factors for poor 30-day perioperative outcomes in morbidly obese patients undergoing elective PLF. Methods: We identified 22 909 patients in the American College of Surgeons National Surgical Quality Improvement Program database who underwent elective PLF. There were 1861 morbidly obese patients. Baseline patient demographics and medical comorbidities were collected. Univariate analysis was performed to compare perioperative complication rates between non-morbidly obese and morbidly obese patients. The 5 most common complications in the morbidly obese group were then selected for multivariate regression analysis to identify independent risk factors for poor 30-day outcomes. Results: Morbidly obese patients had a higher perioperative complication rate. The 5 most common complications were prolonged hospitalization, blood transfusion, readmission, wound complications, and reoperation. Independent risk factors for these complications were age >= 65 years, super obesity (ie, BMI > 48.6), chronic steroid use, American Society of Anesthesiology classification >= 3, poor functional status, long length of fusion >= 4 levels, and extended operative time (ie, operative time >= 318 minutes). Conclusions: Morbidly obese patients are at higher risk of perioperative complications following elective PLF. Modifiable risk factors for the most common complications are obesity and preoperative steroid use.