Understanding the impact of obesity on short-term outcomes and in-hospital costs after instrumented spinal fusion

BACKGROUND: Obesity rates continue to rise along with the number of obese patients undergoing elective spinal fusion. OBJECTIVE: To evaluate the impact of obesity on resource utilization and early complications in patients undergoing surgery for degenerative spine disease. METHODS: A single-institution retrospective analysis was conducted on patients with degenerative spine disease requiring instrumentation between 2008 and 2012. The 801 identified patients were grouped based on a body mass index (BMI) of <30 (nonobese, n 478), ≥30 and <40 (obese, n 283), and alternatively BMIs of ≥40 (morbidly obese, n 40). Baseline characteristics, surgical outcomes and requirements, complications, and cost were compared. Logistic and linear regression analyses were used to determine the strength of association between obesity and outcomes for categorical and continuous data, respectively. RESULTS: Significant differences were found in comorbidities between cohorts. Multivariate analysis revealed significant associations between obesity and longer anesthesia times (30 minutes, P .008), and surgical times (24 minutes, P .02). Additionally, there was a 2.8 times higher rate of wound complications in obese patients (4.2% vs 1.5, P .03), and 2.5 times higher rate of major medical complications (7.8% vs 3.1, P .01). Morbid obesity resulted in a 10 times higher rate of wound complications (P <.001). Morbid obesity resulted in a $9078 (P .005) increase in overall cost of care. CONCLUSION: Increased BMI is associated with longer operative times, increased complication rates, and increased cost independent of comorbidities. These effects are more pronounced with morbidly obese patients, further supporting a role for preoperative weight loss.