Comparing Nasal Secretion Eosinophil Count with Skin Sensitivity Test in Allergic Rhinitis in Ibadan, Nigeria

Abstract

Objectives—The aim of this prospective study was to assess the usefulness of nasal smear eosinophilia compared with a skin sensitivity test for the diagnosis of allergic rhinitis and to determine the degree of correlation between the tests.

Material and Methods—Fifty patients with a clinical history suggestive of nasal allergy and 20 controls were studied. A range of allergens were used for the skin sensitivity test in both groups. Nasal smears were examined by light microscopy.

Results—A positive skin test reaction was demonstrated in 90% of the study population and 25% of the controls, whereas 76% of the patients and 15% of the controls demonstrated significant nasal smear eosinophilia. There was 66% correlation between the skin test and nasal eosinophilia, although this was not statistically significant (correlation coefficient–0.187 p = 0.193). This study does, however, demonstrate that both tests are sensitive for the diagnosis of allergic rhinitis, with sensitivities of 0.90 (95% CI 0.82–0.98) for the skin test and 0.76 (95% CI 0.64–0.88) for nasal eosinophilia.

Conclusion—Both the skin-prick test and the nasal smear eosinophilia showed correlation with the clinical history, although the skin-prick test was more sensitive. No statistically significant correlation was demonstrable between the two tests.

Key words:

• allergic rhinitis
• eosinophilia
• nasal allergy
• nasal eosinophils
• rhinorrhoea
• skin-prick test
• skin sensitivity test