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

AIM: Forced expiratory flow between 25%and75% of vital capacity (FEF25-75%), a spirometric measure of small airways, may predict the presence of airway responsiveness both in asthmatics and in allergic rhinitics. We aimed to search the correlation between FEF25-75% and standard measures of spirometry (FEV1% and FEV1/FVC) in different clinical conditions, that is in children with asthma, in children with asthma and allergic rhinitis, in children with allergic rhinitis and in healthy children METHODS: Children with asthma(n=116), asthma plus allergic rhinitis(n=25), allergic rhinitis(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<0.001); and between FEF25-75% and FEV1/FVC(r=0.740, p<0.001). In AR patients correlation between FEF25-75% and FEV1%(r=0.367, p=0.001); and between FEF25-75% and FEV1/FVC(r=0.534, p<0.001) were less prominent compared to asthmatics but they were still significant and strong. In children with both allergic rhinitis (AR) and asthma correlation between FEF25-75% and FEV1%(r=0.633, p=0.001) and between FEF25-75% and FEV1/FVC(r=0.539, p=0.005) were again significant. Pre-test FEV1% and FEF25-75% in AR patients were lower than that of the control subjects. After the bronchodilation, percentage change in the FEV1 in AR patients were significantly higher then the control subjects(p=0.010). AR patients showed significant increases in FEV1%, (p<0.001), FEF25-75%, (p<0.001) and , (p=0.001) after the bronchodilation test. Within the AR patients only 12/75(16.0%) showed bronchodilation with salbutamol. Among the ones with a FEF25-75% <65% FEV1% was normal in 6/43 (14%) patients in asthmatics and FEV1% was normal in 3/9 (33%) patients in asthma +AR patients.

CONCLUSION: Besides the FEV1% and FEV1/FVC, the FEF25-75% may be a useful and early spirometric parameter to evaluate the children with asthma and or AR.