Exact triggers in acute urticaria and chronic urticaria are largely unknown, with the success of identifying causes of AU varying between 21-68%.
A new investigation into the genesis of urticaria in pediatric patients found that infections were the most frequent trigger, while IgE-mediated allergic triggers were rare.
Approximately 1% of children globally are affected by urticaria, with acute urticaria being the most common form among pediatric populations. Despite being often labelled as “benign”, urticaria has been one of the most common causes of admission to the pediatric emergency department.
As such, dermatologists have attempted to eliminate urticaria by addressing its underlying causes. However, exact triggers in AU and chronic urticaria are largely unknown, with the success of identifying causes of AU varying between 21-68%.
In the current study, investigators led by Ebru Arik Yilmaz, MD, University School of Medicine, Ankara, Turkey, set out to investigate possible and exact triggers of urticaria in children based on medical records and diagnostic testing.
The study included patients 0-18 years who were recorded as L50, which is the urticaria code in the International Classification of Diseases 10 (ICD-10) coding system at Hacettepe University. Patients recorded as L50 between January 1, 2013 and December 31, 2013 were included.
From there, the investigative team evaluated medical records on each patient’s history, possible triggers, demographic characteristics, physical findings, laboratory test results, and treatments given at each PED. Those with incomplete or inconsistent data were excluded from the study.
An urticaria/angioedema episode lasting less than 6 weeks was considered acute and an episode lasting more than 6 weeks was considered chronic
Investigators classified possible triggers into 6 groups including infections, drugs, food, insect bites, blood products, and vaccines. Infection in particular was considered from medical history, physical examination, and laboratory test results in the absence of other triggers.
Finally, telephone interviews were conducted to complete missing data and further diagnostic tests for IgE-mediated allergies.
A total of 60,142 children were admitted to the PED during the study period. Among these children, 842 were recorded with the L50 code. The team confirmed urticaria in 462 (0.8%) patients, 407 (88.1%) of whom had AU and 55 (11.9%) had CU.
Notably, 97 (21%) patients also had angioedema, and urticaria was a component of anaphylaxis in 10 (2.2%) children.
Bezirganoglu and colleagues identified possible triggers in 46% of patients with urticaria based on their history and prior physical examination.
The most common trigger was infections, which effected 18% of all patients with urticaria. This was followed by drugs (11%), foods (8%), infections and drugs (3%), insects (3%), pollen (1%), blood products (0.4%), and vaccines (0.4%).
The most frequently recorded infections were upper respiratory tract infections (74.5%), urinary tract infections (13.2%), gastroenteritis (8.2%), and otitis media (4.1%). Notably, IgE-mediated allergic diseases were diagnosed in only 6% of patients.
Regarding readmissions, investigators found that 22% of patients were readmitted to PED for the same urticaria flare, and urticaria severity was the most important risk factor for readmissions (P<.001).
However, the team saw no relationship between urticaria severity, duration, and triggers.
“Although many suspected causes were noticed, an exact trigger of urticaria could be identified in a small proportion of the children after a detailed diagnostic workup,” the team wrote. “In PED, infections, especially upper respiratory tract infections, are the primary cause of urticaria. IgE-mediated allergic diseases seem to be rare triggers.”
The study, "The common triggers of urticaria in children admitted to the pediatric emergency room," was published online in Pediatric Dermatology.