Abstract Background: There are few epidemiological studies of urticaria, published in the indexed literature (PubMed/Medline). Objective: The study aimed to evaluate the epidemiological and clinical data among patients with urticaria/angioedema attending a reference clinic in Brazil. Methods: Two hundred sixty-seven patients were evaluated retrospectively considering demographic data, time course of the disease, triggering symptoms, the presence of angioedema, complementary laboratory tests including total blood count, reactive-C protein, erythrocyte sedimentation rate, IgE serum levels, and other, as necessary. Results: The most commonly diagnosed type of urticaria was chronic spontaneous urticaria (56.93%). Angioedema was associated with chronic urticaria in 108 patients (40.08%). Study limitations: Unicentered and retrospective. Conclusion: Some relevant findings in this study are the observation of a female prevalence of cases (4-females: 1-man), a result more elevated than demonstrated in previous studies in Europe and Asia, the median age was 43-years old and the delay of time between the diagnosis of urticaria and the admission for treatment in a specialized center was approximately 2-years. Other multicenter studies can better establish these differences in Brazilian patients.

Abstract: Background: In spite of the frequency of chronic urticaria, there are no epidemiological studies on its prevalence in Argentina. Objective: The objective of this study was to define the prevalence and epidemiological characteristics of chronic urticaria patients in Buenos Aires. Methods: The population studied were the members of the Italian Hospital Medical Care Program, a prepaid health maintenance organization located in the urban areas around the Autonomous City of Buenos Aires, Argentina. All patients with diagnosis of chronic urticaria members of the Italian Hospital Medical Care Program, and with at least 12 months of follow up were included in the study. All medical records obtained between January 1st, 2012 and December 31, 2014 were analyzed. The prevalence ratio for chronic urticaria per 100,000 population with 95% CI for December 31, 2014 was calculated. The prevalence rate for the entire population and then discriminated for adults and pediatric patients (less than 18 years old at diagnosis) was assessed. Results: 158,926 members were analyzed. A total of 463 cases of chronic urticaria were identified on prevalence date (68 in pediatrics, 395 in adults), yielding a crude point prevalence ratio of 0.29% (CI 95% 0.26-0.31%). The observed prevalence of chronic urticaria in the adult population was 0.34 % (95% CI 0.31-0.38%), while in pediatrics it was 0.15 % (95% CI 0.11-0.20%). Study limitations: the main weakness is that the results were obtained from an HMO and therefore the possibility of selection bias. Conclusions: chronic urticaria is a global condition. Its prevalence in Buenos Aires is comparable with other countries.