Risk factors for recurrent anaphylaxis-related emergency department visits in the United States

Background: Anaphylaxis is a potentially life-threatening allergic reaction with a strong risk of recurrence. Objective: To assess risk factors associated with recurrent anaphylaxis-related emergency department (ED) visits within 1 year of an ED visit for anaphylaxis in a large observational cohort study. Methods: We used an administrative claims database to identify patients seen from 2008 through 2012 in the ED for anaphylaxis based on an International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code algorithm. Patients with at least 2 years of continuous enrollment in a health plan were included. Multivariable logistic regression analysis was used to determine associations with recurrence of anaphylaxis within 1 year. Results: During the 5-year study period, 7,367 patients (median age, 42 years; <18 years old, 23.3%) met the inclusion criteria. The most common anaphylaxis trigger was unspecified (56.2%), followed by food (25.3%), medication (14.6%), and venom (3.9%). Overall, 3.0% of patients had an additional anaphylaxis-related ED visit within 1 year (3.61 episodes per 100 patient-years). On multivariable analysis, risk factors associated with anaphylaxis recurrence were food trigger (odds ratio [OR], 2.31; 95% confidence interval [CI], 1.34-3.99), history of asthma (OR, 1.30; 95% CI, 1.13-1.51), and intensive care unit admission at the index anaphylaxis event (OR, 1.95; 95% CI, 1.41-2.69). Conclusion: In this contemporary cohort study, history of asthma, food trigger, and greater index anaphylaxis severity, as measured by intensive care unit admission, were associated with a higher likelihood of a recurrent anaphylaxis-related ED visit within 1 year.