What’s Worse, Obesity or Malnutrition in Patients Undergoing Posterior Cervical Instrumentation?

Introduction: While there is extensive literature on the impact of obesity on postoperative complications in spine surgery, research on the effects of malnutrition remains limited. Moreover, no studies have directly compared outcomes between these two patient groups, particularly in the context of posterior cervical instrumentation.

Methods: The TriNetX Research Network was queried to identify adult patients who underwent single- or multi-level posterior spinal instrumentation with preoperative diagnoses of cervical disc disorder, spinal stenosis, radiculopathy, or spondylosis, and had a preoperative serum albumin level measured within 30 days of surgery. The study cohort was divided into two groups: the first group included patients with preoperative serum albumin levels below 3.5 g/dL and a body mass index (BMI) under 30 kg/m^2, while the comparison group consisted of patients with a BMI ≥ 30 kg/m^2 and serum albumin levels ≥ 3.5 g/dL. Further subgroup analysis focused on patients with a BMI ≥ 40 kg/m^2 and albumin levels ≥ 3.5 g/dL. Propensity score matching (PSM) was used to adjust for demographics and comorbidities. Postoperative occurrences of wound dehiscence (WD), surgical site infection (SSI), and the need for reoperation were identified using corresponding procedural and diagnostic codes within 90 days of surgery.

Results: A total of 1,848 patients met the inclusion criteria, with 650 in the malnutrition group and 1,198 in the obesity group. Following PSM, each cohort contained 536 patients. After matching, malnourished patients had significantly higher odds of requiring reoperation compared to obese patients (OR = 1.802). Additionally, following matching, malnourished patients had lower odds of developing SSI or WD and higher odds of requiring reoperation compared to morbidly obese patients (OR = 0.929 and OR = 1.612, respectively), but neither of these results reached statistical significance.

Conclusion : This analysis indicates that patients with malnutrition have an 80% higher odds of requiring reoperation compared to obese patients following cervical spinal instrumentation. Additionally, malnourished patients showed similar odds of developing postoperative complications relative to patients with obesity or morbid obesity undergoing posterior cervical spinal instrumentation.