Role of FEF25-75 as an early marker of bronchial impairment in patients with seasonal allergic rhinitis.

Background: Allergic rhinitis may be associated with asthma. Forced expiratory flow between 25 and 75% of vital capacity (FEF2575) is a measure of small airways narrowing. The aim of this study was to evaluate whether patients with seasonal allergic rhinitis (SAR) without symptoms of asthma might, nevertheless, have airways obstruction both in and out of the pollen season.
Methods: Fifty patients (mean age, 23.7+/-4.9 years) with SAR were evaluated both during and outside the pollen season. All of them had moderate-severe grade of nasal obstruction. Total symptom score, rhinomanometry, nasal lavage, nasal scraping, spirometry, and methacholine (MCH) bronchial challenge were assessed in all subjects.
Results: Although data on forced vital capacity and response to MCH were similar in and out of the pollen season, all other parameters were markedly different. The major finding of the study was that FEF25-75 was significantly associated with nearly all of the parameters considered, including bronchial hyperreactivity, with Pearson R ranging from 31 to 75% and differences in mean FEF25-75 ranging between 14.5 and 16.5% of predicted. The more significant association was with nasal airflow in the pollen season (R = 82.8%; p < 0.001). A significant association persisted for all parameters while controlling for season.
Conclusion: This study highlights the link between upper and lower airways and the role of FEF25-75 as an early marker of bronchial impairment in those patients with SAR alone.