BackgroundMany biomarkers for diagnosis of acute appendicitis in children have been reported, however, the results are still controversial. We assessed the accuracy of neutrophil-lymphocyte ratio (NLR) for diagnosis of acute appendicitis and discriminating simple and complicated appendicitis in children.MethodsWe included 121 patients with acute appendicitis and 49 children with intussusception as controls who were admitted at our hospital from 2013 to 2017. White blood count (WBC), neutrophil, and NLR were compared between groups.ResultsNeutrophil and NLR were significantly higher in the acute appendicitis group than control (76.17 ± 14.41 vs. 62.43 ± 15.9%, p=<0.0001; and 8.44 ± 6.63 vs. 3.38 ± 2.84, p=<0.0001, respectively), while WBC, neutrophil, and NLR were significantly greater in complicated than simple appendicitis (15.86 ± 6.48 vs. 12.64 ± 6.27 × 103/μL, p = 0,008; 82.64 ± 8.41 vs. 68.99 ± 16.23%, p=<0.0001; and 11.32 ± 6.87 vs. 5.25 ± 4.65, p=<0.0001, respectively). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), area under the receiver operating characteristic (ROC) curve, and cutoff point of NLR for diagnosis of acute appendicitis were 83.5%, 57.7%, 81.4%, 61.2%, 0.764, and 2.87, respectively; whereas the sensitivity, specificity, PPV, NPV, area under the ROC curve, and cutoff point of NLR for differentiating complicated and simple appendicitis were 84.6%, 56.5%, 35.5%, 92.9%, 0.790, and 6.59, respectively.ConclusionNLR shows a high accuracy for diagnosis of acute appendicitis and distinguishing a complicated appendicitis from the simple one.