Risk factors for systemic reactions in typical cold urticaria: Results from the COLD-CE study.

BACKGROUND: Cold urticaria (ColdU), that is, the occurrence of wheals or angioedema in response to cold exposure, is classified into typical and atypical forms. The diagnosis of typical ColdU relies on whealing in response to local cold stimulation testing (CST). It can also manifest with cold-induced anaphylaxis (ColdA). We aimed to determine risk factors for ColdA in typical ColdU. METHODS: An international, cross-sectional study COLD-CE was carried out at 32 urticaria centers of reference and excellence (UCAREs). Detailed history was taken and CST with an ice cube and/or TempTest® performed. ColdA was defined as an acute cold-induced involvement of the skin and/or visible mucosal tissue and at least one of: cardiovascular manifestations, difficulty breathing, or gastrointestinal symptoms. RESULTS: Of 551 ColdU patients, 75% (n = 412) had a positive CST and ColdA occurred in 37% (n = 151) of the latter. Cold-induced generalized wheals, angioedema, acral swelling, oropharyngeal/laryngeal symptoms, and itch of earlobes were identified as signs/symptoms of severe disease. ColdA was most commonly provoked by complete cold water immersion and ColdA caused by cold air was more common in countries with a warmer climate. Ten percent (n = 40) of typical ColdU patients had a concomitant chronic spontaneous urticaria (CSU). They had a lower frequency of ColdA than those without CSU (4% vs. 39%, p = .003). We identified the following risk factors for cardiovascular manifestations: previous systemic reaction to a Hymenoptera sting, angioedema, oropharyngeal/laryngeal symptoms, and itchy earlobes. CONCLUSION: ColdA is common in typical ColdU. High-risk patients require education about their condition and how to use an adrenaline autoinjector.

Adrenaline autoinjector is under-prescribed in typical cold urticaria patients living in tropical climate countries.

Background: The diagnosis of typical cold urticaria (ColdU) relies on whealing in response to local cold stimulation testing (CST). It can also manifest with cold-induced anaphylaxis (ColdA). Till date, it is largely unclear how often patients with ColdU receive adrenaline treatment and are provided with an adrenaline autoinjector (AAI). Methods: An international, cross-sectional study, COLD-CE (i.e., comprehensive evaluation of ColdU and other cold-induced reactions), was carried out at 32 UCAREs. Detailed histories were taken and CST with an ice cube and/or TempTest® performed. ColdA was defined as an acute cold-induced (i.e., by cold water, air, or surfaces) involvement of the skin and/or visible mucosal tissue and at least one of the symptoms (cardiovascular manifestations, difficulty breathing, or gastrointestinal symptoms). Results: Of the 551 ColdU patients, 75% (n = 412) had a positive CST. Of them, concomitant chronic spontaneous urticaria was diagnosed in 10%. Of 372 patients with stand-alone ColdU, 69% were women and 91% adults. Their median age was 36 (IQR 26 - 48) years. Patients were also categorized into residents of countries with a tropical (n = 33), temperate (n = 264), or cold (n = 75) climate (Table 1: R13C1, R17C1, R21C1). AAI was more often prescribed to residents of temperate than tropical countries (30% vs. 12%, p = .038; Table 1: R31C1), although the frequency of ColdA did not significantly differ between these countries (44% vs. 42%, p = 1.000; R29C2). Residents of tropical countries had a higher frequency of ColdA induced by cold air than residents of temperate (36% vs. 12%, p = .001; R29C4) or cold (36% vs. 12%, p = .007; R25C4) countries. Cardiovascular manifestations induced by cold air were diagnosed in 33% (n = 11) of residents of tropical countries, but only 18% (n = 2) and 36% (n = 4) of them had received adrenaline and AAI, respectively (R13 - 15C7). Furthermore, hypotension and/or loss of consciousness induced by cold air occurred in 18% (n = 6) of patients, but only 17% (n = 1) received adrenaline (R13 - 14C10). ColdA was induced by complete cold water immersion in 9% (n = 3) of patients, and none of them received adrenaline treatment nor AAI (R13 - 15C3). Conclusion: Our findings suggest that ColdA is undertreated and call for changes in ColdU management.

Update on Omalizumab for Urticaria: What's New in the Literature from Mechanisms to Clinic.

PURPOSE OF REVIEW: Since omalizumab has been approved for urticaria, numerous randomized and real-life observational trials have been published. We reviewed the period January 2017-February 2018. RECENT FINDINGS: Omalizumab is effective for the control of urticaria recalcitrant to antihistamines in different populations globally. The ratio of total serum IgE 4-week/baseline ≥2 can predict response with a high likelihood. In observational real-life trials, doses have been adjusted on an individual basis: in some populations, up to two-thirds of the patients can be controlled with 150 mg/month; however, others are still not controlled with 300 mg/month. In these, 150 mg bimonthly could be tried, before up-dosing to 450 mg/month. On the long run (up to 3 years) omalizumab kept its efficacy. In many patients, dosing intervals could be augmented (6-8 weeks, some even more). After a 12-month treatment, about 20% showed long-term remission without relapse. Some biomarkers are being detected. Adjusting omalizumab doses in urticaria patients could enhance efficacy (shortening dosing interval and/or augmenting dose) and save costs (after 12 months: extending dosing interval and/or reducing dose).

Multinational Drug Survival Study of Omalizumab in Patients With Chronic Urticaria and Potential Predictors for Discontinuation.

Importance: Treating patients with chronic urticaria using omalizumab has been shown to be safe and effective in randomized clinical trials. Multinational studies on long-term omalizumab performance in chronic urticaria in clinical practice settings are lacking, especially on drug survival. Drug survival, which refers to the length of time that patients are treated with a specific drug, is a comprehensive outcome covering effectiveness, safety, and patient and physician preferences. Furthermore, little is known about the reasons and potential predictors for omalizumab discontinuation. Objective: To investigate omalizumab drug survival as well as reasons and potential predictors for discontinuation in a large, diverse population. Design, Setting, and Participants: This international multicenter cohort study was conducted at 14 Urticaria Centers of Reference and Excellence in 10 countries, including all patients with chronic urticaria from these centers who were ever treated with omalizumab. Main Outcomes and Measures: Drug survival analysis was performed to assess time to discontinuation. Patient characteristics and treatment protocols were investigated by Cox regression analysis to identify potential predictors for omalizumab discontinuation. Results: In 2325 patients with chronic urticaria who started omalizumab between June 2009 and July 2022, the mean (SD) age of the cohort was 42 (6) years, and 1650 participants (71%) were female. Overall omalizumab survival rates decreased from 76% to 39% after 1 to 7 years, respectively (median survival time, 3.3 [95 % CI, 2.9-4.0] years), primarily due to discontinuation from well-controlled disease in 576 patients (65%). Ineffectiveness and adverse effects were reasons for discontinuation in a far smaller proportion of patients, totaling 164 patients (18%) and 31 patients (4%), respectively. Fast treatment response was associated with higher rates of omalizumab discontinuation due to well-controlled disease (hazard ratio, 1.45 [95% CI, 1.20-1.75]), and disease duration of more than 2 years was associated with lower rates of discontinuation due to well-controlled disease (HR, 0.81 [95% CI, 0.67-0.98]). Immunosuppressive cotreatment at the start of omalizumab and autoimmune disease was associated with a higher risk for discontinuation due to ineffectiveness (HR, 1.65 [95% CI, 1.12-2.42]). The presence of spontaneous wheals (HR, 0.62 [95% CI, 0.41-0.93]) and access to higher dosages (HR, 0.40 [95% CI, 0.27-0.58) were both associated with a lower risk for discontinuation of omalizumab due to ineffectiveness. Conclusion and Relevance: This multinational omalizumab drug survival cohort study demonstrated that treatment of chronic urticaria with omalizumab in a clinical setting is effective and safe, and well-controlled disease is the main reason for treatment discontinuation. These findings on omalizumab drug survival rates and reasons and potential predictors for discontinuation may guide patients and physicians in clinical decision-making and expectation management. These results may call for the identification of biomarkers for chronic urticaria remission in complete responders to omalizumab treatment.

[Practical update for the diagnosis and treatment of chronic urticaria]. / Actualización práctica de diagnóstico y tratamiento de la urticaria crónica.

Urticaria is a distinctive pattern of inflammatory response of the skin and/or mucous membranes characterized by the sudden appearance of vanishing wheals, angioedema, or both, associated with pruritus. Acute forms are frequent and limited to outbreaks of less than 6 weeks; while the chronic ones have a prevalence of less than 1%, longer duration and can be spontaneous or inducible. The etiopathogenic mechanisms involved in this disease include autoallergy, autoimmunity, and inflammation with cell activation, mainly of the mast cell, leading to its degranulation with the release of vasoactive mediators. Along its approach, diagnostic confirmation, search for indicators of its etiopathogenesis, detection of cofactors that can modulate its activity, recognition of comorbidities, evaluation of possible biomarkers and the assessment of disease activity, impact and control are essential. The pharmacological management aims to control the symptoms, until the urticaria, which is self-resolving, is gone. This is described in a stepwise fashion with increasing complexity.

La urticaria es un patrón distintivo de respuesta inflamatoria de piel y/o mucosas caracterizada por la aparición súbita de ronchas evanescentes, angioedema o ambos, asociados a prurito. Las formas agudas son frecuentes y se limitan a brotes de menos de 6 semanas; mientras que las crónicas tienen una prevalencia menor al 1%, mayor duración y pueden ser espontáneas o inducibles. Los mecanismos etiopatogénicos involucrados en esta enfermedad incluyen la autoalergia, la autoinmunidad y la inflamación con la activación celular, principalmente del mastocito, lo que lleva a su degranulación con liberación de mediadores vasoactivos. En su abordaje son fundamentales la confirmación diagnóstica; la búsqueda de indicadores de su etiopatogenia; la detección de cofactores que pueden modular su actividad; el reconocimiento de comorbilidades; la evaluación de posibles biomarcadores y, el impacto en la calidad de vida, el registro de la actividad y el control de la enfermedad. El manejo farmacológico tiene por objetivo controlar los síntomas, mientras la urticaria resuelve de forma espontánea. Este se describe de forma escalonada con una complejidad creciente.

The Benefit of Complete Response to Treatment in Patients With Chronic Spontaneous Urticaria-CURE Results.

BACKGROUND AND OBJECTIVE: Chronic spontaneous urticaria (CSU) is a distressing disease. We report real-world data from the global Chronic Urticaria Registry (CURE) about associations between various CSU states and sleep impairment, plus important health-related quality-of-life (HRQoL) outcomes and compared different methods to assess CSU states. METHODS: CURE data were collected at baseline and 6-monthly follow-ups (FU). Assessments included CSU states using the Urticaria Control Test (UCT), weekly Urticaria Activity Score (UAS7), and Physician Global Assessment (PhyGA) of treatment response. Complete response to treatment (CR, UAS7 = 0), complete control of disease (CC, UCT = 16), and PhyGA = CR were assessed, plus the Dermatology Life Quality Index and the Chronic Urticaria Quality-of-Life Questionnaire (CU-Q2oL) sleep domain. RESULTS: Overall, 2078 patients were included. At baseline, 9.8%, 17.9%, and 42.3% of patients had UCT = 16, UAS7 = 0, or PhyGA = CR, respectively, which increased at FU1 and FU2. Patients with higher UCT scores had better sleep and HRQoL. The presence of angioedema without wheals, episodic disease, omalizumab treatment, and male sex were associated with CC (P < .05). Among 469 patients who achieved CC or CR, 16.4% (n = 77) showed CC or CR with all 3 instruments. Agreement between UCT = 16 and UAS7 = 0 measurements was moderate (κ = 0.581), but poor between UCT = 16 and PhyGA = CR (κ = 0.208). CONCLUSIONS: Few patients had CR/CC of their CSU at baseline entry. Disease control strongly related to good sleep and better HRQoL; therefore, it is important to aim for CR in CSU treatment. Patient-reported UCT and UAS7 assessments demonstrated a more accurate measurement of CSU state versus physician assessments.

How are patients with chronic urticaria interested in using information and communication technologies to guide their healthcare? A UCARE study.

BACKGROUND: Patients with chronic urticaria (CU) are increasingly using information and communication technologies (ICTs) to manage their health. What CU patients expect from ICTs and which ICTs they prefer remains unknown. We assessed why CU patients use ICTs, which ones they prefer, and what drives their expectations and choices. METHODS: In this cross-sectional study, 1841 patients across 17 countries were recruited at UCAREs (Urticaria Centers of Reference and Excellence). Patients with CU who were >12 years old completed a 23-item questionnaire. RESULTS: Most patients were interested in receiving disease information (87.3%), asking physicians about CU (84.1%), and communicating with other patients through ICTs (65.6%). For receiving disease information, patients preferred one-to-one and one-to-many ICTs, especially web browsers. One-to-one ICTs were also the ICTs of choice for asking physicians about urticaria and for communicating with other patients, and e-mail and WhatsApp were the preferred ICTs, respectively. Many-to-many ICTs such as Facebook, Instagram, LinkedIn, and Twitter were least preferred for all 3 purposes. Living in rural areas and higher education were linked to higher odds of being interested in receiving disease information, asking physicians, and communicating with patients through ICTs. CONCLUSIONS: Most patients and especially patients with higher education who live in rural areas are interested in using ICTs for their healthcare, but prefer different ICTs for different purposes, ie, web browsers for obtaining information, e-mail for asking physicians, and WhatsApp for communicating with other patients. Our findings may help to improve ICTs for CU.

Chronic urticaria patients are interested in apps to monitor their disease activity and control: A UCARE CURICT analysis.

BACKGROUND: Information/communication technologies such as mobile phone applications (apps) would enable chronic urticaria (CU) patients to self-evaluate their disease activity and control. Yet, recently Antó et al (2021) reported a global paucity of such apps for patients with CU. In this analysis, we assessed patient interest in using apps to monitor CU disease activity and control using questions from the chronic urticaria information and communication technologies (CURICT) study. METHODS: The methodology for CURICT has been reported. Briefly, a 23-item questionnaire was completed by 1841 CU patients from 17 UCAREs across 17 countries. Here, we analyzed patient responses to the CURICT questions on the use of apps for urticaria-related purposes. RESULTS: As previously published, the majority of respondents had chronic spontaneous urticaria (CSU; 63%; 18% chronic inducible urticaria (CIndU) [CIndu]; 19% with both), were female (70%) and in urban areas (75%). Over half of patients were very/extremely interested in an app to monitor disease activity (51%) and control (53%), while only ∼1/10 were not. Patients with both urticaria types versus those with CSU only (odds ratio [OR], 1.36 [1.03-1.79]) and females versus males (OR [95% CI], 1.47 [1.17-1.85]) were more likely to be very to extremely interested in an app to assess disease control. CONCLUSIONS: Overall, half of the patients with CU were very to extremely interested in using an app to assess their disease activity and control. Development of well-designed apps, specific to disease types (CSU, CIndU, CSU + CIndU, etc), validated by experts across platforms would help improve the management and possibly outcomes of CU treatment while providing important patient information to be used in future research.

[The epidemiology of asthma in adults. An insight]. / Epidemiología del asma en adultos. Una visión introspectiva.

BACKGROUND: Asthma is a chronic disease with a great impact on public health and on the patients' quality of life. In Latin America, there are scarce epidemiological studies. OBJECTIVE: To describe the prevalence of asthma and the clinical-demographic characteristics in an adult population from a private health system in the City of Buenos Aires. METHODS: A cross-sectional study of adults who were enrolled in the medical program of a private health system in Buenos Aires between January 1st, 2017, and January 1st, 2018. All the patients that were included in the study had been diagnosed with asthma. RESULTS: The prevalence of asthma in the adult patients of a prepaid health system in the City of Buenos Aires was of 6 % (n = 66, IC 95 % = 5-7), and the prevalence of severe asthma among the same group was of 5 % (n = 3, IC 95 % = 1-13). Most patients had intermittent and mild asthma. CONCLUSION: This study provides new data about the epidemiology of asthma in the region.

Antecedentes: El asma es una enfermedad crónica de gran impacto en la salud pública y en la calidad de vida de los pacientes. En Latinoamérica existen escasos estudios epidemiológicos Objetivo: Describir la prevalencia del asma y las características clínico-demográficas en una población adulta de un sistema de salud privado de la ciudad de Buenos Aires. Métodos: Estudio de corte transversal de adultos afiliados al programa médico de un sistema de salud privado de Buenos Aires, entre el 1 de enero de 2017 y 1 de enero de 2018, con diagnóstico médico de asma. Resultados: La prevalencia de asma en pacientes adultos de un sistema de salud prepago en la ciudad de Buenos Aires fue de 6 % (n = 66, IC 95 % = 5-7) y de asma grave de 5 % (n = 3 IC 95 % = 1-13) La mayoría de los pacientes presentaron asma intermitente y leve. Conclusión: El estudio aporta nuevos datos sobre la epidemiología del asma en la región.

The usage, quality and relevance of information and communications technologies in patients with chronic urticaria: A UCARE study.

BACKGROUND: Chronic urticaria (CU) is characterized by itchy recurrent wheals, angioedema, or both for 6 weeks or longer. CU can greatly impact patients' physical and emotional quality of life. Patients with chronic conditions are increasingly seeking information from information and communications technologies (ICTs) to manage their health. The objective of this study was to assess the frequency of usage and preference of ICTs from the perspective of patients with CU. METHODS: In this cross-sectional study, 1800 patients were recruited from primary healthcare centers, university hospitals or specialized clinics that form part of the UCARE (Urticaria Centers of Reference and Excellence) network throughout 16 countries. Patients were >12 years old and had physician-diagnosed chronic spontaneous urticaria (CSU) or chronic inducible urticaria (CIndU). Patients completed a 23-item questionnaire containing questions about ICT usage, including the type, frequency, preference, and quality, answers to which were recorded in a standardized database at each center. For analysis, ICTs were categorized into 3 groups as follows: one-to-one: SMS, WhatsApp, Skype, and email; one-to-many: YouTube, web browsers, and blogs or forums; many-to-many: Instagram, Twitter, Facebook, and LinkedIn. RESULTS: Overall, 99.6% of CU patients had access to ICT platforms and 96.7% had internet access. Daily, 85.4% patients used one-to-one ICT platforms most often, followed by one-to-many ICTs (75.5%) and many-to-many ICTs (59.2%). The daily ICT usage was highest for web browsers (72.7%) and WhatsApp (70.0%). The general usage of ICT platforms increased in patients with higher levels of education. One-to-many was the preferred ICT category for obtaining general health information (78.3%) and for CU-related information (75.4%). A web browser (77.6%) was by far the most commonly used ICT to obtain general health information, followed by YouTube (25.8%) and Facebook (16.3%). Similarly, for CU-specific information, 3 out of 4 patients (74.6%) used a web browser, 20.9% used YouTube, and 13.6% used Facebook. One in 5 (21.6%) patients did not use any form of ICT for obtaining information on CU. The quality of the information obtained from one-to-many ICTs was rated much more often as very interesting and of good quality for general health information (53.5%) and CU-related information (51.5%) as compared to the other categories. CONCLUSIONS: Usage of ICTs for health and CU-specific information is extremely high in all countries analyzed, with web browsers being the preferred ICT platform.

Chronic urticaria in a health maintenance organization of Buenos Aires, Argentina - new data that increase global knowledge of this disease.

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.

Actualización práctica de diagnóstico y tratamiento de la urticaria crónica / Practical update for the diagnosis and treatment of chronic urticaria

Resumen La urticaria es un patrón distintivo de respuesta inflamatoria de piel y/o mucosas caracterizada por la aparición súbita de ronchas evanescentes, angioedema o ambos, asociados a prurito. Las formas agudas son frecuentes y se limitan a brotes de menos de 6 sema nas; mientras que las crónicas tienen una prevalencia menor al 1%, mayor duración y pueden ser espontáneas o inducibles. Los mecanismos etiopatogénicos involucrados en esta enfermedad incluyen la autoalergia, la autoinmunidad y la inflamación con la activación celular, principalmente del mastocito, lo que lleva a su degranulación con libe ración de mediadores vasoactivos. En su abordaje son fundamentales la confirmación diagnóstica; la búsqueda de indicadores de su etiopa togenia; la detección de cofactores que pueden modular su actividad; el reconocimiento de comorbilidades; la evaluación de posibles biomarcadores y, el impacto en la calidad de vida, el registro de la actividad y el control de la enfermedad. El manejo farmacológico tiene por objetivo controlar los síntomas, mientras la urticaria resuelve de forma espontánea. Este se describe de forma escalonada con una complejidad creciente.

Abstract Urticaria is a distinctive pattern of inflammatory re sponse of the skin and/or mucous membranes charac terized by the sudden appearance of vanishing wheals, angioedema, or both, associated with pruritus. Acute forms are frequent and limited to outbreaks of less than 6 weeks; while the chronic ones have a prevalence of less than 1%, longer duration and can be spontaneous or inducible. The etiopathogenic mechanisms involved in this disease include autoallergy, autoimmunity, and inflam mation with cell activation, mainly of the mast cell, leading to its degranulation with the release of vasoac tive mediators. Along its approach, diagnostic confirmation, search for indicators of its etiopathogenesis, detection of cofactors that can modulate its activity, recognition of comorbidi ties, evaluation of possible biomarkers and the assess ment of disease activity, impact and control are essential. The pharmacological management aims to control the symptoms, until the urticaria, which is self-resolv ing, is gone. This is described in a stepwise fashion with increasing complexity.

Direct Medical Costs of Chronic Urticaria in a Private Health Organization of Buenos Aires, Argentina.

BACKGROUND: Scarce studies address the issue of resource consumption and direct health care costs of patients diagnosed with adult-onset chronic urticaria (CU). OBJECTIVES: To estimate medical resource consumption and direct health care costs of affected patients in a private health maintenance organization in Buenos Aires, Argentina. METHODS: Patients diagnosed with adult-onset CU (International Classification of Diseases, Ninth Revision, Clinical Modification code 708.1, 708.8, or 708.9) and who were members of the Italian Hospital Medical Care Program were included in the study. All data on hospitalizations, drug prescription, outpatient episodes, consultations, and investigations/tests in the 12 months before inclusion in the study were considered for the estimation of medical resource consumption and direct health care costs. Third-quarter 2014 costs were obtained from the Italian Hospital Medical Care Program and converted into US dollars (using the November 2014 exchange rate). RESULTS: A total of 232 patients were included in the study. The mean age at diagnosis was 54.2 ± 20.0 years, and the mean disease duration was 5.4 ± 2.6 years (range, 2-22 years). Of the total number of patients, 75% had allergists as their usual source of care, 23% had dermatologists, 18% had internists, and 3% had rheumatologists. Only 7.8% of the patients had an emergency room admission to manage CU symptoms. To manage the disease, 57.8% of patients used antihistamines and 11.6% used oral corticosteroids. The most relevant source of cost was the medical treatment received, followed by physician visits. The average yearly direct cost per patient was US $1015 ± $752 (95% confidence interval 803-2003). CONCLUSIONS: This is the first Argentine study that evaluated the costs of CU considering the direct medical costs of the disease. The study provides information on resource utilization and the disease-related economic burden, which is valuable to better understand CU in the local setting. Future research that takes into consideration the direct and indirect costs of the disease will expand knowledge and improve management of the disease.

Chronic urticaria in a health maintenance organization of Buenos Aires, Argentina - new data that increase global knowledge of this disease

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.