What’s Worse, Obesity or Malnutrition in Patients Undergoing Multi-level Posterior Lumbar Instrumentation?

Introduction: Obesity and malnutrition have both been linked to adverse outcomes following spine surgery. However, there is uncertainty regarding which condition poses a greater risk, and no studies have directly compared surgical outcomes between these two patient populations.

Methods: The TriNetX Research Network was utilized to identify adult patients who underwent multi-level (3 to 12 levels) posterior spinal instrumentation with preoperative diagnoses of lumbar spinal stenosis or spondylolisthesis. The study cohort was stratified into two groups: one group consisted of patients with preoperative serum albumin levels below 3.5 g/dL and a body mass index (BMI) under 30 kg/m^2 within 30 days prior to surgery, while the comparison group included patients with a BMI ≥ 30 kg/m^2 and serum albumin levels ≥ 3.5 g/dL. A subgroup analysis was also performed for patients with a BMI ≥ 40 kg/m^2 and albumin levels ≥ 3.5 g/dL. Propensity score matching (PSM) was conducted to adjust for demographics and comorbidities. Postoperative outcomes, including wound dehiscence (WD), surgical site infection (SSI), and the need for reoperation, were assessed using relevant procedural and diagnostic codes within 90 days of surgery.

Results: A total of 6,857 patients met the inclusion criteria, with 1,418 patients in the malnutrition group and 5,439 in the obesity group. After PSM, both cohorts comprised 1,383 patients. Additional analysis included matching 646 patients in the malnutrition cohort with 646 patients in the morbid obesity cohort. Post-matching analysis revealed that malnourished patients had higher odds of SSI or WD compared to obese and morbidly obese patients (OR = 1.251 and OR = 1.027, respectively), though these differences did not reach statistical significance. However, malnourished patients demonstrated significantly higher odds of requiring reoperation within 90 days compared to both obese (OR = 1.803) and morbidly obese patients (OR = 1.686).

Conclusion : This analysis demonstrates that patients with malnutrition have comparable odds of postoperative complications and significantly higher odds of reoperation within 90 days when compared to patients with obesity or morbid obesity undergoing multi-level posterior lumbar spinal instrumentation.