Neutrophil-to-lymphocyte ratio as a predictor of postoperative complications and readmissions after appendectomy in children.

To analyze the role of neutrophil-to-lymphocyte ratio (NLR) in predicting the development of postoperative complications and readmission after appendectomy in children. A retrospective single-centered case-control study was conducted on children who underwent appendectomy between 2017 and 2020. Demographics, time since symptoms onset, laboratory tests at admission, postoperative complications, and readmissions in the first 30 days after surgery were recorded. Sensitivity and specificity analysis of the parameters evaluated were determined by the area under the curve (AUC) represented on the receiver operating characteristic (ROC) curves. A total of 1,214 patients (765 males; 449 females) were included, with a median age at diagnosis of 10.4 years. The median time from symptom onset was 24 h. During the first 30 days after surgery, 149 postoperative complications were reported (12.3%). NLR at admission presented the highest AUC (0.753), with a cut-off point of 10.5 for maximum sensitivity (68.7%) and specificity (86.1%). Readmissions were reported in 45 cases (3.7%). NLR at admission presented an AUC of 0.794 significantly higher than neutrophils (0.696), leukocytes (0.654), and time since symptom onset (0.622), making these differences statistically significant (p < 0.001). The cut-off point of NLR > 12.4 was estimated, with a maximum sensitivity and specificity of 71.0% and 82.3% for predicting readmission. NLR is an independent predictor of postoperative complications and readmission in children with acute appendicitis. While its application in routine clinical practice has yet to be established, the NLR may provide clinicians with a tool for identifying high-risk surgical patients.