Bronchial hyperresponsiveness in patients with cholinergic urticaria.

Background Cholinergic urticaria is occasionally associated with bronchospasm, even in patients without a history of asthma; the underlying mechanism has not been elucidated. Objective To evaluate bronchial hyperresponsiveness (BHR) in patients with cholinergic urticaria compared with healthy adults and patients with chronic urticaria. Methods Patients with a history of cholinergic urticaria and a positive ergometric test result constitute the study group. History was reviewed and physical examination and spirometry were performed to exclude exercise-induced anaphylaxis and exercise-induced asthma. Patients with chronic urticaria and healthy volunteers were used as positive and negative controls, respectively. All 3 groups were evaluated for BHR using a methacholine challenge test. Results Fifty-nine adults participated in the study: 30 patients with cholinergic urticaria, 15 with chronic urticaria, and 14 healthy volunteers. BHR was demonstrated in 13 of 30 patients (43%) in the study group, 1 of 15 patients with chronic urticaria (7%), and 1 of 14 healthy volunteers (7%); the observed difference was statistically significant. Further analysis of the study group demonstrated the existence of 2 subpopulations of patients with cholinergic urticaria, which were discriminated on the basis of intensity and duration of symptoms, with 96.7% accuracy. In addition, a statistically significant correlation was found between patient age and disease duration and between intensity and frequency of symptoms. Conclusions Evaluation of patients with cholinergic urticaria should probably include BHR. A formula based on duration and intensity of cholinergic urticaria symptoms is provided as a tool for the prediction of BHR.