Nasal eosinophilia and its clinical correlates in patients with allergic rhinitis at a Kenyan tertiary hospital

Introduction Allergic Rhinitis (AR) is an IgE- mediated inflammatory disease of the nasal mucosa. While the diagnosis mainly relies on a typical clinical history and physical examination, the evaluation of eosinophils in nasal smears is considered a direct marker of inflammation and can play a role in the diagnosis and monitoring of treatment response. The aim of this study was to evaluate the levels of nasal eosinophils among patients with AR, and to correlate these levels with disease severity and frequency. Material and methods This was a descriptive cross-sectional study conducted at a tertiary referral hospital in Kenya from November 2022 to January 2023. Patients were diagnosed with AR using the Score for Allergic Rhinitis (SFAR) questionnaire. A Total Nasal Symptom Score (TNSS) questionnaire was administered to evaluate for nasal symptoms and assign severity scores. The patients were categorized according to the Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines into either intermittent or persistent allergic rhinitis groups, and further sub-classified into mild, or moderate-to-severe AR. Nasal smears were collected to quantify eosinophil counts. Results The study included 73 patients comprising 35 (47.9%) males and 38 (52.1%) females. The median age of the participants was 19 years (Interquartile Range 9–38), with an age range of 5–84 years. Most patients presented with intermittent symptoms (58.9%) and moderate-to-severe disease (61.6%). Pathological levels of eosinophils were found in 15 patients (20.5%). However, there was no statistically significant correlation between the level of nasal eosinophilia and either disease severity ( p = 0.23) or symptom frequency ( p = 0.80). Conclusion In this study, nasal eosinophils counts did not correlate with the severity or frequency of AR as defined by the ARIA classification. These findings suggest that while the presence of nasal eosinophilia is useful for confirming the underlying type 2 inflammation in AR, it should not be used as a standalone biomarker to determine disease severity or guide management.