Does preoperative prognostic nutrition index predict surgical site infection after spine surgery?

Purpose: Malnutrition is reported as one of the risk factors for surgical site infection (SSI). The prognostic nutritional index (PNI) is a simple method for nutritional evaluation. However, little is known about the relationship between SSI and the PNI in patients after spine surgery. We aimed to determine independent predictors of SSI after spine surgery.

Methods: We analyzed 1115 patients who underwent spine surgery (369 males, 746 females, mean age 56 years, follow-up period: at least 1 year). Patients were divided into SSI and non-SSI groups. Preoperative risk factors, including PNI (10 × serum albumin [g/dL] + 0.005 × total lymphocyte count [/μL]), were assessed.

Results: Postoperatively, 43 patients (3.9%) experienced SSI. Univariate analysis showed that preoperative PNI (48.5 vs 51.7; p < 0.01), revision status (p < 0.05), male sex (p < 0.01), body mass index (BMI) (p < 0.05), and usage of anticoagulant agents (p < 0.05) differed significantly between the SSI and non-SSI groups. Multivariate logistic regression analysis showed that preoperative PNI (odds ratio [OR], 0.94; 95% confidence interval [CI]: 0.90-0.98; p < 0.01), male sex (OR, 2.64; 95% CI: 1.40-4.99; p < 0.01), length of surgery ≥ 180 min (OR, 2.78; 95% CI: 1.30-5.96; p < 0.01), BMI ≥ 30 kg/m² (OR, 2.89; 95% CI: 1.20-6.97; p < 0.05), and revision status (OR, 2.30; 95% CI: 1.07-4.98; p < 0.05) were independently associated with SSI postoperatively.

Conclusion: Lower preoperative PNI was found to be a risk factor for SSI after spine surgery. Patients with lower preoperative PNI values should be cautioned about the risk of SSI and provide adequate informed consent.