ABSTRACT
BACKGROUND: Allergic rhinitis is often associated with bronchial asthma, and intranasal treatment with topical corticosteroids reduces bronchial responsiveness. OBJECTIVE: In this study, it was evaluated that the bronchial responsiveness to methacholine increased in non-asthmatic adults with house dust mites (HDM)-sensitive allergic rhinitis compared to those without, chronic nasal symptoms. SUBJECTS AND METHODS: A questionnaire, skin prick t,est to common inhalant allergens, and methacholine bronchial provocation test (MBPT) were performed in a total of 216 subjects, who were composed of 40 non-asthmatic subjects with HDM-sensitive allergic rhinitis (HAR), 63 HDM-sensitive subjects without nasal symptoms (HS), and 113 non-atopic subjects without nasal symptoms (NHS). The bronchial responsiveness was evaluated by positive rate of MBPT (PC,-methacholine200mg/ml), provocative concentration of methacholine at which FEV, decline to 15% compared to baseline value (PC,-methacholine), and slope of dose-response curve (%fall of FEV, / log[last concentrat,ion of methacholine, mg/ml]). RESULTS: Positive rate of MBPT was significantly increased in HAR than in HS and NHS, and there was no difference between HS and NHS (77.9% vs. 50.7% vs. 38.0%). Log PC[5- methacholine was lower in HAR than in HS and NHS, and lower in HS than in NHS (mean+ SE, 1.568+0.126 vs. 2.05+0.085 vs. 2.277+0.047). Slope of dose-response curve was higher in HAR than in HS and NHS, and there was no difference bet,ween HS and NHS (mean+SE, 22.7 + 11.3 vs. 7.3+ 1.2 vs. 4.9+ 0.5%/mg/ml); CONCLUSION: In non-asthmatic adults with HDM-sensitive allergic rhinitis, the bronchial responsiveness to methacholine increased compared to those without chronic rhinitis.