Chronic inducible urticaria: confirmation through challenge tests and response to treatment

Objective To evaluate the positivity of challenge tests of patients suspected of chronic inducible urticaria and the response to treatment. Methods A retrospective study of electronic medical records of patients suspected of chronic inducible urticaria. All patients were submitted to challenge tests with triggering stimuli, according to the clinical history and, subsequently, the response to drug treatment was evaluated. Results A total of 191 patients with suspected chronic inducible urticaria were included. It was confirmed in 118 patients and 122 positive tests (4 patients with 2 different positive tests). Most had dermographic urticaria (70.3%), followed by cholinergic urticaria (17.8%). Regarding treatment, 28% responded to antihistamine in licensed doses, 34.7% with increased doses, 9.3% responded to the addition of another medication. The concomitance of chronic inducible urticaria and chronic spontaneous urticaria was found in 35.3% of patients, being more frequent in females, with longer time to control symptoms and higher frequency of cholinergic urticaria. Conclusion The confirmation of chronic inducible urticaria in patients with this suspicion, after challenge tests, was high. There was a good response to antihistamine. In the concomitance of chronic spontaneous urticaria, longer time to control symptoms and higher frequency of cholinergic urticaria were observed.