Comparing nasal secretion eosinophil count with skin sensitivity test in allergic rhinitis in Ibadan, Nigeria.

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.