Pulmonary function parameters in patients with allergic rhinitis

Rhinitis patients may have abnormal airway function as demonstrated by an obstruction in large or small airways and increased bronchial reactivity to inhaled nonspecific provocating agents. The nonspecific bronchial hyperreactivity (BHR) is particularly important in patients with rhinitis because they are more prone to develop asthma. However, the factors associated with BHR in rhinitis patients have not yet been explained. Therefore, we performed this study to determine the differences in airflow rates, and bronchial and nasal resistance between nonasthmatic rhinitis patients with or without BHR, and to evaluate the relationship between these parameters and bronchial reactivity to methacholine. A total of 66 patients with allergic rhinitis but not asthma were selected for the study and divided into two groups; Group 1 (40 patients with allergic rhinitis and negative mechacholine provocation test) and Group 2 (26 patients with allergic rhinitis and positive methacholine provocation test). Pulmonary function tests, methacholine provocation tests, anterior rhinomanometry, and skin prick tests were performed on the patients. The study groups were homogeneous with regard to gender, age, duration of illness, and smoking ratio. Expiratory airflow parameters including FVC, FEV1, PEFR, and FEF25 were similar in both groups, however FEV1/FVC, FEF25-75, FEF50, and FEF75 were significantly lower in Group 2. Additionally, sRaw was significantly higher in Group 2 and negatively correlated with the expiratory airflow parameters for small airways. Total nasal resistance was not different between the groups. There was no correlation between nasal resistance and BHR to methacholine or airway resistance. The present study suggests that nonasthmatic rhinitis patients with BHR may have mild but significant changes in the small airways. Clinical and functional follow-up of these patients should assess the long-term consequences of these parameters and their clinical importance.