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.

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.

Background: Only two studies have analyzed the incidence of anaphylaxis during admission to hospital. We have analyzed the incidence of anaphylaxis among hospitalized patients and determined the timing of and risk factors for episodes of anaphylaxis. Methods: Our study was performed between 1999 and 2005. We used the definition of anaphylaxis of the NIAID-FAAN symposium. Cases of anaphylaxis were extracted from an official database of discharge diagnoses coded according to the International Classification of Diseases, Clinical Modification, Ninth Revision (ICD-9-CM), Sixth Edition. Specific and generic codes related to anaphylaxis were chosen. This strategy revealed 83.3% (95% confidence interval, CI, 47–99%) of all episodes of anaphylaxis in a pilot study. The incidence of episodes of anaphylaxis and the hazard ratios were calculated for the different variables. Results: We observed a crude cumulative incidence of 1.5 episodes of anaphylaxis (95% CI, 0.9–1.9) in 5,000 admissions. The cumulative incidence according to the Standardized European Population was 1.6 cases in 5,000 admissions (95% CI, 0.8–2.3). Cox regression analysis showed that anaphylaxis occurs mainly in young people (0.97; 95% CI, 0.95–0.99) and its incidence differs according to the clinical unit. The Vascular Surgery Unit had the highest incidence rate (hazard ratio 7.7; 95% CI, 2.1–28.6). Males had a lower risk of suffering from anaphylaxis than females (0.5; 95% CI, 0.2–0.9). Conclusions: Anaphylaxis is a very rare event among hospitalized patients. Female gender, young age and admission to the Vascular Surgery Unit favored the occurrence of episodes of anaphylaxis among hospitalized patients.

It is difficult to compare studies from different populations and using different ascertainment techniques. These first data from Latin America are in general agreement with many studies.

Summary 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.