Patients with AR and BHR have a higher risk of developing asthma. In this study, we investigated whether reactivity to aeroallergens in skin prick test (SPT) and serum eosinophil cationic protein (sECP) levels could be used to predict BHR in AR.

Fifty-nine consecutive patients diagnosed with AR between February 2001 and February 2002 were studied. SPTs were performed using grass, tree, weed, parietaria, Alternaria, Aspergillus, mites and cat and dog dander extracts. Methacholine challenge test was performed using spirometry.

Methacholine induced BHR was detected in 23 patients (39%). Of the 59 patients, 14 had one positive SPT response, 35 had 2-4 and 10 had >4 positive responses. There was a significant inverse correlation between methacholine PC₂₀ doses and the number of positive SPTs (p=0.031, r=−0.28). BHR(+) patients had a mean of 4 positive SPTs while BHR(-) patients had a mean of 2.6 (p=0.04). Of the 23 BHR(+) patients, 39% had >4 positive SPTs. In contrast, only 2.7% of the BHR(-) patients had >4 positive SPTs (p=0.0001). The mean methacholine PC₂₀ dose was 5.05 ± 9.72mg/ml in patients with >4 positive SPTs, 23.4 ± 14mg/ml in patients with 2-4 and 23.6 ± 13.4mg/ml in patients with one positive response (p=0.001 for >4 vs. 2–4, P=0.002 for >4 vs. 1). There was no correlation between sECP levels and methacholine PC₂₀ doses.

AR 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 AR remains to be determined.