DETERMINANTS OF BRONCHIAL HYPERRESPONSIVENESS IN SUBJECTS WITH RHINITIS

Subjects with rhinitis but without asthma may have coexisting bronchial hyperresponsiveness, although the reasons for this are uncertain. To evaluate the factors that determine BHR in rhinitis we examined 410 patients with symptomatic rhinitis with forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC)>or=80% of the predicted value. In all subjects a skin prick test (SPT) was performed, a determination of total serum IgE and an eosinophils count in the blood. Of the 410 subjects we found that 161 (39.3%) exhibited a methacholine PD20 of 800 mg or less (Group A), whereas 249 (60.7%) had a methacholine PD20 more of 800 mg (Group B). Despite the matched mean values for FEV1 and FVC, compared with Group B, Group A had a lower predicted forced expiratory flow between 25% and 75%(FEF25%-75%) (86.7 +/- 12.0 vs. 93.7 +/- 7.3, P < 0.0001). A great portion of the subjects of the Group Ain respect to subjects of the Group B were exposed to passive smoke (37.8% vs. 22.0%, P = 0.0008), reported having mothers with asthma (34.1% vs. 6.0%, P < 0.0001), presented a positive skin prick test (93.7% vs. 67.0%, P < 0.0001), had higher levels of total serum IgE (geometric mean of Log10 2.46 +/- 0.27 kU/L vs. 2.06 +/- 0.38 kU/L, P < 0.0001) and higher blood eosinophil counts (geometric mean of Log10 2.67 +/- 0.07 x 10(-3) mL vs. 2.57 +/- 0.09 x 10(-3) mL, P < 0.0001), and reported increased nasal obstruction (2.0 (95% CI 1.8 to 2.2) vs. 0.6 (95% CI 0.5 to 0.7), P < 0.0001). Logistic regression demonstrates that nasal obstruction (OR 2.19, 95% CI 1.72 to 2.80) and the presence of positive SPT (OR 6.15, 95% CI 2.42 to 15.61) were the most available predictors to discriminate between subjects with BHR and subjects without BHR. In addition, BHR was positively related to blood eosinophil counts (OR= 2.80, 95% CI 1.54 to 5.07), FEF25%-75% values (OR= 2.72, 95% CI 1.23 to 5.99) and familiarity (mother) for asthma (OR = 2.45, 95% CI 1.10 to 5.46). Whereas passive smoke and total serum IgE were not positively related to BHR. Increased nasal obstruction and the presence of positive SPT were the most available predictors to discriminate between subjects with and without BHR. Finally, BHR was positively related to blood eosinophil counts, FEF25%-75% values and to familiarity (mother) for asthma.