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

Introduction: While extensive research has explored the impact of obesity on spine surgery outcomes, there is a notable lack of studies addressing malnutrition in this context. Additionally, no studies have directly compared these risk factors.

Methods: The TriNetX Research Network was queried to identify adult patients who underwent single-level posterior spinal instrumentation with preoperative diagnoses of lumbar spinal stenosis or spondylolisthesis. The study cohort was divided into two groups: the first group comprised patients with preoperative serum albumin levels below 3.5 g/dL and a body mass index (BMI) less than 30 kg/m^2 within 30 days of surgery, while the comparison group included patients with a BMI ≥ 30 kg/m^2 and serum albumin levels ≥ 3.5 g/dL. Further subgroup analysis was conducted on patients with a BMI ≥ 40 kg/m^2 and an albumin level ≥ 3.5 g/dL. Propensity score matching (PSM) was performed 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 codes within 90 days of surgery.

Results: A total of 4,777 patients met the inclusion criteria with 544 in the malnutrition group and 4,233 in the obesity group. Following PSM, each cohort contained 537 patients. After matching, malnourished patients had lower odds of developing SSI or WD and of requiring reoperation compared to obese patients (OR = 0.629 and OR = 0.809, respectively), though these results were not statistically significant. In further analysis of matched malnourished and morbidly obese cohorts, malnourished patients had lower odds of developing SSI or WD and of needing reoperation compared to morbidly obese patients (OR = 0.418 and OR = 0.755, respectively); however, only the reduced odds of SSI or WD was statistically significant.

Conclusion : This analysis indicates that patients with malnutrition have similar odds of developing postoperative complications compared to patients with obesity following single-level lumbar spinal instrumentation. These findings highlight comparable risk profiles between malnourished and obese patient populations in terms of spinal surgery outcomes.