Forced expiratory flow between 25% and 75% of vital capacity as a predictor for bronchial hyperresponsiveness in children with allergic rhinitis

ABSTRACT

PURPOSE: Allergic rhinitis (AR) is regarded as a risk factor for asthma and bronchial hyperresponsiveness (BHR) is frequently observed in patients with AR. The purpose of this study is to analyze the characteristics of AR patients with BHR and identify factors that contribute to the incidence of BHR. METHODS: The medical records of a total of 176 children with AR were analyzed retrospectively. All patients were evaluated by performing spirometry and a methacholine challenge test. RESULTS: One hundred and fifty-five patients (88%) were classified as the BHR-negative group and 21 patients (12%) were classified as the BHR-positive group. Forced expiratory flow between 25% and 75% of vital capacity (FEF25-75 %predicted) was reduced, and total eosinphil counts, total immunoglobulin E (IgE) level, and serum specific IgE levels of Dermatophagoides pteronyssinus and Dermatophagoides farinae were higher in the BHR-positive group compared to the BHR-negative group. However, FEF25-75 was the only statistically significant predictor for the presence of BHR on multivariate logistic regression analysis. The cutoff value to distinguish BHR-positive subjects obtained from a receiver operating characteristics curve of FEF25-75 was 88.4%. A higher frequency of BHR was found in the group with a FEF25-75 less than 88.4%, and the sensitivity, specificity, positive predictive value and negative predictive value were 57.1%, 80.6%, 28.6%, and 93.3%, respectively. CONCLUSION: Reduced FEF25-75 values in children with AR can be helpful in predicting BHR. Children with low FEF25-75 in spirometric tests should be followed closely for apparent onset of clinical symptoms of asthma.