The determinants of bronchial hyperresponsiveness in patients with allergic rhinitis

Background: Patients with allergic rhinitis and bronchial hyperresponsiveness (BHR) may be at higher risk of developing asthma. Objective: To investigate whether reactivity to aeroallergens in skin prick testing (SPT) and serum eosinophil cationic protein levels can be used to predict BHR in allergic rhinitis patients. Methods: Fifty-nine consecutive patients with allergic rhinitis underwent SPTs using grass, tree, weed, parietaria, Alternaria, Aspergillus, miles, and cat and dog dander extracts. Methacholine challenge tests were performed using spirometry. Results: Methacholine-induced BHR was detected in 23 patients (39%). Of 59 patients, 14 had 1 positive SPT response, 35 had 2 to 4 positive responses, and 10 had more than 4 positive responses. There was a significant inverse correlation between methacholine provocation concentration that caused a decrease in forced expiratory Volume in 1 second of 20% (PC20) and the number of positive SPT responses (r = -0.28; P =.03). The BHR-positive patients had a mean of 4 positive SPT responses, whereas BHR-negative patients had a mean of 2.6 (P =.04). Nine BHR-positive patients (39%) and only 1 BHR-negative patient (3%) had more than 4 positive SPT responses (P <.001). There was no correlation between serum eosinophil cationic protein levels and methacholine PC,, doses. There was a strong association between hyperresponsiveness to methacholine and both cat and dog dander sensitivity (P <.001 and P =.001, respectively). Conclusions: Allergic rhinitis patients with SPT responses to a higher number of allergens are more likely to have BHR. Whether the number of positive SPT responses correlates with the risk of developing asthma in allergic rhinitis patients remains to be determined.