Effect of polyelectrolytic properties of DNA on protonating cytosine

Data were collected on 390 patients who attended a dermatology out-patient department in whom a clinical diagnosis of urticaria was made. Two hundred and thirty-seven (61%) were women. The median age at onset of symptoms was 40 years. Sixty-one (16%) had acute urticaria with symptoms of less than 6 weeks duration at presentation. The disorder was deemed idiopathic in 217 (56%) patients, 59 (15%) had physical urticaria and 57 (15%) had both idiopathic and physical urticaria. Thirty-eight (10%) patients reported intolerance to salicylate or similar drugs, and 31 of these 38 patients also had idiopathic symptoms. One hundred and seventy-two (44%) patients reported a good response to treatment with H1 receptor antagonists. Those who gained little or no benefit from these drugs were more likely to have a physical urticaria (P < 0.05) or to report intolerance reactions (P < 0.05). Only 113 (29%) patients were asymptomatic when discharged. One in five of a small sample contacted still had symptoms 10 years after presentation. Patients seen in an urticaria clinic were less likely to have routine investigations performed and more likely to be discharged at first attendance. When compared with previous published surveys, these figures show a lower proportion of intolerance reactions and a greater proportion of patients responding well to treatment with antihistamines.