The common triggers of urticaria in children admitted to the pediatric emergency room

Background Urticaria frequently causes pediatric emergency department (PED) admissions. Children with urticaria may unnecessarily avoid suspected allergens. We aimed to investigate the possible and exact triggers of urticaria in children admitted to the PED. Methods Medical records of children admitted to the PED within a 1-year period were evaluated for the International Classification of Diseases 10 (ICD-10) L50 urticaria code, noting symptoms, and possible triggers of urticaria. We performed telephone interviews to complete the missing data and further diagnostic tests for IgE-mediated allergies to identify the exact triggers of urticaria. Results Among 60,142 children, 462 (0.8%) with the L50 code were evaluated. Possible triggers based on the history and physical examination could be identified in 46%: infections (18%), drugs (11%), foods (8%), infections and drugs (3%), insects (3%), pollen (1%), blood products (0.4%), and vaccines (0.4%). The most frequent infections related to urticaria were upper respiratory tract infections (74.5%), urinary tract infections (13.2%), gastroenteritis (8.2%), and otitis media (4.1%). After a diagnostic workup, IgE-mediated allergic diseases were diagnosed in 6% of patients. Twenty-two percent of the patients had multiple PED admission for the same urticaria flare. Urticaria severity was found to be the most important risk factor for readmissions to the PED (odds ratio: 3.86; 95% confidence interval: 2.39-6.23; p < .001). No relationship between urticaria severity, duration, and the triggers was present. Conclusions Despite detailed diagnostic tests, IgE-mediated allergic triggers were rarely the cause of urticaria in children admitted to the PED. Infections are the most frequent trigger. Severe urticaria causes more frequent readmissions to the PED.