BACKGROUND

There are currently limited data regarding the epidemiology of anaphylaxis.

OBJECTIVE

To estimate the incidence of anaphylaxis from all causes, to explore the variety of diagnoses that may predispose to an anaphylactic episode, and to estimate the rate of recurrence of anaphylaxis in patients with no asthma, nonsevere asthma, and severe asthma.

METHODS

The Health Improvement Network database provided data on individuals 10 to 79 years old who had been enrolled for at least 1 year with a general practitioner in the United Kingdom and had at least 1 health contact in the year before entering the study.

RESULTS

Anaphylaxis incidence rates (per 100,000 person-years) were 21.28 (95% CI, 17.64-25.44) and 50.45 (95% CI, 44.67-56.76) in the no asthma and overall asthma cohorts, respectively. Risk of anaphylaxis was greater in the nonsevere asthma (relative risk, 2.07; 95% CI, 1.65-2.60) and severe asthma (relative risk, 3.29; 95% CI, 2.47-3.47) subgroups compared with the no asthma cohort. The incidence rate of anaphylaxis was higher in women than men (22.65 vs 19.56 per 100,000 person-years). Within the overall asthma population, patients at significantly increased risk of anaphylaxis included those with allergic rhinitis or atopic dermatitis, and current users of antihistamines, oral steroids, or antibiotics (compared with nonusers). Drug and food allergies were the most common known causes of anaphylaxis.

CONCLUSION

Patients with asthma have a greater risk of anaphylaxis than those without asthma, and the risk is greater in severe than nonsevere asthma. Women are at higher risk of anaphylaxis than men, especially those with severe asthma.