What’s worse, obesity or malnutrition in patients undergoing multi-level posterior lumbar instrumentation?

Introduction: Patients with obesity and those with malnutrition have both been associated with poorer outcomes following spine surgery. However, there remains uncertainty regarding which of these conditions represents a more significant risk factor, and no studies to date have directly compared surgical outcomes between these two patient groups.

Methods: The TriNetX Research Network was queried 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 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 comprised patients with a BMI of 30 kg/m^2 or higher and serum albumin levels of 3.5 g/dL or higher. Additional subgroup analysis focused on patients with a BMI of 40 kg/m^2 or greater and an albumin level of 3.5 g/dL or higher. Propensity score matching was applied to control for potential confounders. Postoperative wound dehiscence, surgical site infection (SSI), and the need for a return to the operating room were identified using corresponding procedural and diagnostic codes within 90 days of the index surgery.

Results: A total of 6,857 patients met the inclusion criteria, with 1,418 in the malnutrition group and 5,439 in the obesity group. After propensity score matching, malnourished patients demonstrated higher odds of developing SSI or wound dehiscence compared to obese and morbidly obese patients (OR = 1.251 and OR = 1.027, respectively), though these findings were not statistically significant. Additionally, malnourished patients showed significantly higher odds of requiring reoperation within 90 days compared to both obese and morbidly obese patients (OR = 1.803 and OR = 1.686, respectively).

Conclusion : This large-scale retrospective analysis, utilizing propensity score matching, indicates that patients with malnutrition, defined by hypoalbuminemia ( < 3.5 g/dL), have comparable odds of developing SSI and wound dehiscence and higher odds of requiring reoperation compared to patients with obesity or morbid obesity following multi-level posterior lumbar spinal instrumentation. These findings highlight the elevated risk profiles of malnourished patients relative to obese patient populations in multi-level spinal surgery outcomes.