Reduced forced expiratory flow between 25% and 75% of vital capacity in children with allergic rhinitis without asthmatic symptoms.

Allergic rhinitis (AR) and asthma are closely associated in children. Reduced FEF which reflects small airway airflow limitation is frequently observed in asthma. This study aimed to examine the proportion of small airway dysfunction in children with AR and to determine its associated factors. The medical records of 144 aged 6-18-year children with AR without overt asthmatic symptoms were retrospectively reviewed. Subjects were divided into 2 groups according to the FEF values; normal FEF group ( = 129) and reduced FEF group ( = 15). Clinical data, allergen sensitization profile, exhaled nitric oxide, spirometry, and methacholine provocation test results were compared between the two groups. The mean FEV and FEF values in the reduced FEF group (73.5 ± 9.4%pred and 56.0 ± 7.7%pred, respectively) were significantly lower than in the normal FEF group (87.0 ± 12.5%pred and 99.1 ± 21.4%pred, respectively). The mean disease duration was significantly longer in the reduced FEF group than in the normal FEF group (5.39 ± 1.85 y vs 3.14 ± 1.80 y,  < 0.001). Subjects with positive bronchial hyperresponsiveness (MChPC<16 mg/mL) were more frequently detected in the reduced FEF group than in the normal FEF group (26.7% vs 8.52%,  = 0.013). Long disease duration and severity of AR were significantly associated with impaired FEF values. Subjects with AR alone may have impaired FEF values which is considered as a marker of early bronchial involvement. Longer disease duration and severity of AR are important risk factors for progressive declines in small airway function. Physicians should be aware of need for the measurement of FEF values for early detection of small airway dysfunction, particularly in children with severe long-lasting allergic rhinitis.