Epidemiology of anaphylaxis.

Knowledge about the epidemiology of anaphylaxis is based on data from various sources: clinical practice, large secondary clinical and administrative databases of primary care or hospitalized patients, and recent surveys with representative samples of the general population. As several similar results are often reported in several publications and populations, such findings are highly like to be robust. One such finding is that the incidence and prevalence of anaphylaxis are higher than previously thought. Publications from the last 5 years reveal an incidence of between 50 and 112 episodes per 100 000 person-years; estimated prevalence is 0.3-5.1% depending on the rigour of the definitions used. Figures are higher in children, especially those aged 0-4 years. Publications from various geographical areas based on clinical and administrative data on hospitalized patients suggest that the frequency of admissions due to anaphylaxis has increased (5-7-fold in the last 10-15 years). Other publications point to a geographic gradient in the incidence of anaphylaxis, with higher frequencies recorded in areas with few hours of sunlight. However, these trends could be the result of factors other than a real change in the incidence of anaphylaxis, such as changes in disease coding and in the care provided. Based on data from the records of voluntary declarations of death by physicians and from large national databases, death from anaphylaxis remains very infrequent and stands at 0.35-1.06 deaths per million people per year, with no increases observed in the last 10-15 years. Although anaphylaxis can be fatal, recurrence of anaphylaxis--especially that associated with atopic diseases and hymenoptera stings--affects 26.5-54% of patients.

Epidemiology of Anaphylaxis: Contributions From the Last 10 Years.

Knowledge of the epidemiology of anaphylaxis has improved during the last 10 years thanks to the increased number of publications with improved methodological robustness. Consequently, we better understand the distribution and frequency of anaphylaxis and the characteristics of fatal anaphylaxis. We now know that anaphylaxis is more frequent than previously thought (up to 50-103 cases per 100 000 person-years), although the distribution differs with the age group (up to 3 times in patients aged 0-4 years), cause (food-induced anaphylaxis is more frequent in young people, drug-induced and Hymenoptera anaphylaxis in older patients), and geographical area (more prevalent in areas with less sunlight). A controversial and unresolved issue is whether this high incidence of anaphylaxis is a real increase or merely the result of better identification of anaphylaxis by the attending physician. Recurrence of anaphylaxis has been recorded in one-third of cases, although it is the least studied area of the epidemiology of anaphylaxis. Fatal anaphylaxis, on the other hand, has been widely studied. We know that death from anaphylaxis is a rare and extraordinary event (0.12 to 1.06 deaths per million person-years) and more likely in older individuals in the case of drug and Hymenoptera anaphylaxis. Studies conducted during the last 10 years are highly powered since they include large numbers of patients (national records of hospitalized patients) over long time periods (10-20 years) or have been conducted with representative samples of the general population.

Self-Management of Anaphylaxis Is Not Optimal.

BACKGROUND: Our objective was to ascertain the degree of adherence to recommendations made to patients with anaphylaxis, most of whom were attended in our allergy outpatient clinic. METHODS: A questionnaire was sent to 1512 patients who had experienced anaphylaxis and completed by 887. The chosen definition of anaphylaxis was that of the National Institute of Allergy and Infectious Diseases and the Food Allergy and Anaphylaxis Network Symposium. We evaluated the prescription, purchase, and use of epinephrine auto-injectors and oral drugs, as well as the avoidance of allergens involved in previous anaphylaxis episodes. RESULTS: Most patients (94.53%) reported that they had received advice on avoidance of responsible allergens after their allergy workup. Epinephrine auto-injectors and oral drugs were prescribed according to the subtype of anaphylaxis. Only 30.74% of patients used the epinephrine auto-injector; 54.26% took oral medication. Most patients (88.3%) avoided the allergen. CONCLUSIONS: Despite general agreement that anaphylaxis occurring in the community should be treated with epinephrine auto-injectors, use of these devices to treat recurrences was low in our patients. Oral medication intake was more common than the epinephrine auto-injector in all subtypes. In order to increase adherence to epinephrine auto-injectors, it is necessary to think beyond the measures recommended during regular visits to allergy outpatient clinics.

Incidence of anaphylaxis in the city of Alcorcon (Spain): a population-based study.

BACKGROUND: Relatively few studies have examined the incidence of anaphylaxis in the general population. OBJECTIVE: To report the incidence of anaphylaxis among the general population of the city of Alcorcon, Spain, using various public health care databases. METHODS: Episodes of anaphylaxis were recovered using validated alphanumeric strings in different fields of electronic clinical records used in the different public health settings in the city of Alcorcon (primary care, Emergency Department, hospitalized patients and Allergy Outpatient Clinic). Patients with anaphylaxis were tracked across the different clinical settings in Alcorcon. RESULTS: The incidence of anaphylaxis in Alcorcon was 103.37 episodes per 100 000 person-years (total standardized incidence rate of 112.2). There was a peak of 313.58 episodes in the 0-4 years age group and a different distribution of incidence rates (although non-significant) among different age groups between male patients and female patients. In most age groups, incidence tended to be higher for female patients aged over 10 years. Patients were attended at two or more levels in 76.78% of episodes, and a new evaluation was often made at a primary care centre (71.43%), Allergy Outpatient Clinic (75.6%), or both after the episode (58.93%). CONCLUSION AND CLINICAL RELEVANCE: This study revealed a higher rate of anaphylaxis than that in previous studies, although this incidence rate is probably lower than the real incidence rate. Studies exploring potential methodological, genetic and environmental factors accounting for these higher rates of anaphylaxis are required.

Incidence of anaphylaxis and subtypes of anaphylaxis in a general hospital emergency department.

BACKGROUND: The absence of large-scale international studies means that data on anaphylaxis in emergency departments in different geographic areas are still necessary. OBJECTIVE: To determine the incidence of anaphylaxis and subtypes of anaphylaxis and their distribution by age group in the emergency department of Hospital Universitario Fundación Alcorcon, Alcorcon (Madrid), Spain. METHODS: Our study was performed between 2004 and 2005. We used the definition of anaphylaxis established by the NIAID-FAAN Symposium. Patient information was collected from the electronic clinical records of the emergency department using alphanumeric strings to identify acute allergic illnesses. This strategy recovered 91.7% of all anaphylaxis episodes in a pilot study. RESULTS: We observed a crude cumulative incidence of 0.9 episodes of anaphylaxis per 1000 emergency episodes (95% confidence interval [CI], 0.8-1.1), and 0.8 episodes per 1000 people (95% CI, 0.7-0.9). Standardized cumulative incidence of anaphylaxis according to the Standardized European Population was 1.1 (95% CI, 0.9-1.2). On analyzing the 213 cases of anaphylaxis, we discovered that the main cause was food (28.6%), followed by drugs (28.2%), unknown causes (27.2%), Anisakis (10.8%), Hymenoptera venom (3.3%), exercise (2.4%), and latex (0.9%). Food-induced anaphylaxis was less frequent in all groups older than the 0-4 age group in both reference populations (people who attend the emergency department and the general population). CONCLUSIONS: The cumulative incidence of anaphylaxis in our emergency department is low. Anaphylaxis by foods is more frequent in the 0-4 year group than in the other age groups. Drugs and food are the most frequent causes of anaphylaxis in our emergency department.