Neutrophil-to-lymphocyte ratio as a predictor of surgical site infection in acute appendicitis

Background: Surgical site infection (SSI) is one of the most common complications after appendectomy, which carries high associated morbidity. Therefore, it is essential to determine SSI predictive factors in order to prevent its occurrence. The aim of this study is to explore the role of neutrophil-to-lymphocyte ratio (NLR) as a predictor of SSI after appendectomy in children. Methods: A single-center, retrospective cohort study was performed in children who underwent appendectomy between 2017-2020. Demographics, time since symptoms onset, laboratory tests at admission, ultrasound appendiceal diameter, rate of complicated appendicitis, surgical aproach, surgery time and SSI rate were analyzed. Follow-up was performed during hospitalization and at outpatient clinic at 2 weeks and 30 days postoperatively to assess the surgical wound aspect. Diagnostic cut-off values of these markers for SSI prediction were based on the significance in the univariate analysis. Variables with a P value <0.05 in the univariate analysis were then entered into the multivariate analysis. Results: 47.9 min; P<0.001). SSI group presented higher counts of leukocytes, neutrophils and NLR than control group (P<0.001). NLR was the parameter with the highest area under the curve (AUC) (AUC =0.808; P<0.001), with a cut-off point of 9.8 with maximum sensitivity (77.8%) and specificity (72.7%). NLR was an independent predictive factor for SSI in the multivariate analysis [odds ratio (OR) 1.82 (1.13-2.73); P<0.01]. Conclusions: NLR value at admission was the most promising predictive factor for the development of SSI in children undergoing appendectomy. It is an easy, simple, inexpensive, and rapid method to detect patients at high risk for SSI. However, further prospective studies are still needed to confirm these results.