Table 1_Association between preoperative controlling nutritional status score and surgical site infection following instrumented posterior lumbar interbody fusion.docx

Objective<p>This study aimed to investigate the association between preoperative Controlling Nutritional Status (CONUT) score and surgical site infection (SSI) after instrumented posterior lumbar interbody fusion (PLIF).</p>Methods<p>This retrospective cohort study included patients who underwent instrumented PLIF for lumbar degenerative disease at our institution between January 2021 and March 2025. SSI events within 12 months postoperatively were identified through medical records and follow-up assessment.

Restricted cubic spline (RCS) analysis was performed to evaluate the potential nonlinear association between CONUT score and SSI risk. Based on the observed risk pattern and clinical interpretability, an exploratory cutoff of 3 was used to dichotomize patients for categorical analysis. Multivariable logistic regression was performed to assess the independent association between CONUT score and SSI, with sensitivity analysis treating CONUT as a continuous variable.</p>Results<p>Among 1,414 patients included, 43 (3.0%) developed SSI within 12 months postoperatively.