Objective: The neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) are blood markers of systemic inflammatory response (SIR). The purpose of this study was to investigate the clinical utility of SIR markers for severe anaphylaxis in children.

Materials and Methods: The medical records of 103 children aged 0-18 years experiencing a total of 204 anaphylactic episodes between 2013 and 2020 were analyzed. The children were categorized into mild, moderate, and severe anaphylaxis groups. The SIR markers were measured during anaphylaxis.

Results: Anaphylaxis was mild in 47 (45.6%), moderate in 28 (27.2%), and severe in 28 (27.2%) children. NLR was higher in children with severe anaphylaxis (p=0.001). The ROC curve demonstrated by the increase in NLR yielded an area under the curve (AUC) of 0.666 (CI: 0.5-0.79), with a cut-off value of ≥2.1 in discriminating severe anaphylaxis from mild and moderate anaphylaxis, with sensitivity of 73.6% and specificity of 76.9%. The risk of severe anaphylaxis increased in drug- and venom-induced reactions (OR: 11.83, 95%CI: 2.89-48.38, p=0.001, and OR: 13.03, 95%CI: 2.82-60.22, p=0.001, respectively), and in case of NLR ≥ 2.1 (OR: 3.92, 95%CI: 1.53-10.04, p=0.004), particularly in children aged ≤6 years (OR: 9.33, 95%CI: 1.27- 68.59, p=0.028).

Conclusion: NLR was higher in severe anaphylaxis than mild and moderate, whereas MLR and PLR were not. NLR could be used as a quick and easily accessible marker to predict the severity of anaphylaxis in children.