Nasal smear eosinophils and allergic rhinitis

Area of Science:

• Allergy and Immunology
• Otorhinolaryngology

Background:

• Allergic rhinitis (AR) is a common condition affecting the upper airways.
• Accurate diagnosis and assessment of AR severity are crucial for effective management.

Purpose of the Study:

• To investigate the association between nasal smear eosinophil counts and allergic rhinitis.
• To establish a diagnostic cutoff value for nasal eosinophils in AR.
• To explore the relationship between eosinophil counts and AR characteristics, including coexisting asthma.

Main Methods:

• A case-control study involving 100 patients with diagnosed AR and 100 age- and sex-matched controls.
• Nasal smears were analyzed for eosinophil counts per high-power field (HPF).
• Patients underwent clinical assessment for asthma and spirometry.

Main Results:

• A statistically significant difference in mean eosinophil counts was observed between AR patients and controls (p = 0.000).
• A nasal smear eosinophil count >0.3 per HPF demonstrated 100% specificity and 100% positive predictive value for AR.
• Forty percent of AR patients had coexisting asthma, but eosinophil counts did not correlate with AR symptoms, duration, type, severity, or asthma presence.

Conclusions:

• Nasal smear eosinophil counts exceeding 0.3 per HPF serve as a highly specific diagnostic marker for allergic rhinitis.
• Eosinophil counts in nasal smears are not reliable indicators of the extent or characteristics of allergic airway inflammation or associated asthma.