Systemic Inflammatory Indices as Predictors of Treatment Response in Allergic Rhinitis: A Prospective 6 Month Cohort Study

Objectives: Allergic rhinitis (AR) is increasingly recognized as a systemic inflammatory condition. While symptom scores are commonly used for disease monitoring, objective biomarkers to predict treatment outcomes remain limited. This study evaluated systemic inflammatory indices (neutrophil-to-lymphocyte ratio NLR, platelet-to-lymphocyte ratio PLR, systemic immune-inflammation index SII, eosinophil count, and total immunoglobulin E IgE) as biomarkers in AR over 6 month follow-up. Methods: This prospective cohort study enrolled 105 patients with moderate-to-severe persistent AR and 92 matched healthy controls. Baseline and 6 month measurements included complete blood count–derived indices and total serum IgE. Symptom severity was assessed using Total Nasal Symptom Score and visual analog scales. ROC analyses determined optimal cutoff values for predicting treatment response. Results: At baseline, AR patients had significantly-higher NLR, PLR, SII, and eosinophil counts than controls (all P 2.7 showed the strongest predictive value for nonresponse (sensitivity 84%, specificity 76%, OR 4.2). PLR >240, SII >1100, eosinophils >600/µL, and IgE >450 IU/mL were also associated with increased nonresponse risk. Total IgE remained stable and was not useful for short-term monitoring. A mixed-effects longitudinal model confirmed that reductions in NLR, PLR, and eosinophil count were significantly greater in AR patients than in controls, supporting that these biomarker changes were treatment related. Conclusion: NLR, PLR, SII, and eosinophil count are promising biomarkers for monitoring disease activity and predicting treatment response in AR. NLR may serve as a simple, cost-effective tool for early risk stratification. These findings support integrating routine hematologic markers into clinical management of AR.