Morbid obesity and lumbar fusion in patients older than 65 years: Complications, readmissions, costs, and length of stay

Study Design. Retrospective database review. Objective. The aim of this study was to determine how both morbid obesity (body mass index [BMI] ≥40) and obesity (BMI 30-39.9) modify 90-day complication rates and 30-day readmission rates following 1- to 2-level, primary, lumbar spinal fusion surgery for degenerative pathology in an elderly population. Summary of Background Data. In the United States, both obese and elderly patients are known to have increased risk of complication, yet both demographics are increasingly undergoing elective lumbar spine surgery. Methods. Medicare data from 2005 to 2012 were queried for patients who underwent primary 1- to 2-level posterolateral lumbar fusion for degenerative pathology. Elderly patients undergoing elective surgery were selected and separated into three cohorts: morbidly obese (BMI ≥40; n=2594), obese (BMI ≥30,<40] (n=5534), and nonobese controls (n=48,210). Each pathologic cohort was matched to a unique subcohort from the control population. Ninety-day medical and surgical complication rates, 30-day readmission rates, length of stay (LOS), and hospital costs were then compared. Results. Both morbidly obese and obese patients had significantly higher odds of experiencing any one major medical complication (odds ratio [OR] 1.79; P<0.0001 and OR 1.32; P<0.0001, respectively). Wound infection (OR 3.71; P<0.0001 and OR 2.22; P<0.0001) and dehiscence (OR 3.80; P<0.0001 and OR 2.59; P<0.0001) rates were increased in morbidly obese and obese patients, respectively. Thirty-day readmissions, length of stay, and in-hospital costs were increased, with patients with morbid obesity incurring charges almost $8000 greater than controls. Conclusion. Patients with both obesity and morbid obesity are at significantly increased risk of major medical complications, wound complications, and 30-day readmissions. Additionally, both groups of patients have significantly increased LOS and hospital costs. Both obese and morbidly obese patients should be appropriately counseled of these risks and must be carefully selected to reduce postoperative morbidity.