Trends in hospitalizations related to anaphylaxis, angioedema, and urticaria in the United States

Background: Data on the prevalence of allergic disorders over time are limited. Recent studies have noted marked increase in the prevalence of allergic conditions in different parts of the world. Objective: To examine time trends in the prevalence of anaphylaxis, angioedema, and urticaria in the United States. Methods: Using the largest inpatient National Inpatient Sample data in the United States from 2001 to 2014, adults admitted with a primary diagnosis of anaphylaxis, angioedema, or urticaria were identified based on International Classification of Diseases, Ninth Revision codes. Yearly distribution of hospital admissions was stratified per different age groups, and yearly trends of hospitalizations related to anaphylaxis, angioedema, and urticaria were calculated. Results: Although an increasing trend in the rate of hospitalizations was seen for angioedema (annual percentage change [APC], 4.48), a decreasing trend (APC, −2.19) was observed for urticaria-related hospitalizations. Overall anaphylaxis-related hospitalizations were noted to be stable, but a significant increasing trend was observed among those aged 5 to 14 years (APC, 4.19), mostly because of the subgroup of food-related hospitalizations (APC, 5.86). Angioedema-related hospitalizations were highest among the 35- to 64-year age group (APC, 5.38). Conclusion: An increasing trend of hospitalizations has been observed for allergic conditions, with varying age distribution according to the nature of eliciting agent and susceptibility of different age groups. Although angioedema has been observed as an increasing problem in older populations, food-induced anaphylaxis is an increasing concern in the younger population.