Spirometry in children with asthma and/or allergic rhinitis: comparison of FEF25-75% with the standard measures

BACKGROUND Forced expiratory flow between 25% and 75% of vital capacity (FEF25-75%), a spirometric measure of small airways, may predict the presence of airway responsiveness both in asthmatics and in allergic rhinitis (AR). We aimed to search the correlation between FEF25-75% and standard measures of spirometry (forced expiratory volume in the first second [FEV1%] and FEV1/FVC [forced vital capacity]) in different clinical conditions, that is in children with asthma, in children with asthma and AR, in children with AR and in healthy children. METHODS Children with asthma (N.=116), asthma plus AR (N.=25), AR (N.=75) and healthy controls (N.=52) were evaluated. Clinical examinations, spirometry and bronchodilation tests were performed. RESULTS In asthmatics there was a strong correlation between FEF25-75% and FEV1% (r=0.596, P