The Impact of Body Mass Index on Early Readmission and Reoperation Following Endoscopic vs. Open Lumbar Surgery: A Nationwide Analysis

Introduction: Lumbar degenerative spine disease (LDSD) is a prevalent condition with a huge global burden, often leading to chronic lower back pain and disability. Surgical interventions, particularly for lumbar disc herniation, have evolved from open discectomy to less invasive techniques such as endoscopic lumbar discectomy (ELD), which have achieved reduced recovery times. However, the risks of postoperative complications, as well as early readmissions and reoperations still persist, presumably containing association with patient characteristics that remains uncovered. This study investigates the impact of body mass index (BMI), one of the most prominent baseline index, on early readmission and reoperation rates in LDSD patients treated by endoscopic or open lumbar surgery.

Methods: We identified 123,457 patients undergoing lumbar spine surgery nationwide using the American College of Surgeons National Surgical Quality Improvement Project (ACS-NSQIP) database (2017-2022), and categorized them by BMI into five groups: normal weight, overweight, obese, severely obese, and underweight. Patients were followed 30 days postoperatively, and data of complications, early readmission, and reoperation rates were analyzed. Logistic regression and random forest models were used to predict these outcomes, with model performance evaluated via area under the receiver operating characteristic (AUC) curve.

Results: Severely obese and underweight patients exhibited significantly higher rates of postoperative complications, including surgical site infections (SSIs), pulmonary embolism, and sepsis. Both groups had elevated early readmission (severely obese: 5.4%, underweight: 4.4%) and reoperation rates (severely obese: 3.2%, underweight: 3.8%) compared to normal-weight patients. Endoscopic surgery was associated with lower reoperation risks across all BMI categories, particularly in the underweight and obese groups.

Conclusion : BMI significantly influences the outcomes of surgically-treated LDSD patients, and BMI extremes, both severely obese and underweight, were strong predictors of higher risks for complications, early readmission and reoperation. Endoscopic surgery appears to improve the clinical outcomes, particularly for underweight patients. These findings underscore the need for individualized perioperative management strategies for patients with extreme BMI to improve clinical outcomes.