Objective: Allergic rhinitis (AR) is a common chronic inflammatory disease of childhood that exhibits distinct clinical phenotypes. The aim of this study was to compare the distribution of hematological and inflammatory parameters among seasonal, perennial, and mixed phenotypes in pediatric patients with AR and to evaluate the role of hematological indices in phenotype discrimination.

Materials and Methods: This retrospective, cross-sectional study included 124 patients diagnosed with allergic rhinitis. Patients were classified as having perennial, seasonal, or mixed allergic rhinitis. Complete blood count parameters obtained during the non-pollen season (December–February) and derived inflammatory indices were analyzed in all patients.

Results: Of the study population, 65.3% were male. Asthma comorbidity was significantly more frequent in the mixed allergic rhinitis group (p<0.001). Absolute eosinophil count, eosinophil-to-lymphocyte ratio (ELR), and eosinophil-to-neutrophil ratio (ENR) were significantly higher in the mixed phenotype compared with the perennial and seasonal groups (all p<0.01). In multivariable logistic regression analysis, absolute eosinophil count (per 100 cells/µL increase; odds ratio [OR]=1.54, 95% confidence interval [CI]: 1.21– 1.97; p<0.001) and asthma comorbidity (OR=2.19, 95% CI: 1.01–4.75; p=0.047) were identified as independent predictors of non- seasonal allergic rhinitis (NSAR). Receiver operating characteristic (ROC) analysis demonstrated that eosinophil count had moderate discriminatory performance for differentiating NSAR from seasonal allergic rhinitis (area under the curve [AUC]=0.692, 95% CI: 0.600–0.785). An optimal cutoff value of ≥195 cells/µL yielded a sensitivity of 77.8% and a specificity of 54.3%.

Conclusion: In pediatric allergic rhinitis, the mixed phenotype is associated with a more pronounced systemic eosinophilic inflammatory response. Absolute eosinophil count and asthma comorbidity emerge as independent predictors of non-seasonal allergic rhinitis. These readily available parameters from routine clinical practice may serve as complementary biomarkers for the evaluation of allergic rhinitis phenotypes.