Abstract
This study identified cut-off values for allergy markers for use in the diagnosis of allergic rhinitis in the absence of other allergic diseases. Total immunoglobulin E (IgE), eosinophil cationic protein (ECP) and the numbers of eosinophils were measured in serum samples from 442 patients with typical symptoms of allergic rhinitis. A definite diagnosis was made on the basis of the presence of specific IgE levels. Cut-off values with a maximal discrimination to diagnose allergic rhinitis were found to be 98.7 IU/ml, 24.7 μg/ml and 4.0% for total IgE, ECP and eosinophils, respectively. Sensitivity, specificity and odds ratio for these values were 75.2%, 69.7% and 6.93, respectively, for total IgE, 55.7%, 74.4% and 3.70 for ECP, and 57.5%, 72.0% and 3.47 for eosinophils. A composite score representing positive results for all three markers had a positive predictive value of 85.3%, with an odds ratio of 8.55. It was concluded that total serum IgE, ECP and eosinophil percentage are strong predictors of allergic rhinitis and the determination of cut-off values for these markers can aid in the diagnosis of allergic rhinitis in the clinical setting.