Prevalence and Causes of Childhood Urticaria

http://e-aair.org 189 Urticaria is one of the most common skin disease, characterized by the development of wheals (hives), angioedema, or both and it is classified as acute or chronic form based on the duration of illness. Urticaria of longer than 6 weeks duration is classified as chronic urticaria, which is further classified into chronic spontaneous or inducible urticaria. Acute urticaria is more prevalent than chronic urticaria; however, chronic urticaria has a more significant impact on quality of life due to recurrence and unknown etiology. As in adults, the causes are different between acute and chronic urticaria in children, and it is difficult to determine the exact prevalence of childhood urticaria due to lack of papulation-based studies. Common causes or triggers of acute urticaria in children include infections, medications, and foods, while acute spontaneous urticaria is common in young children with atopy. Infection appears to be a more frequent predisposing cause of urticaria in infants and children compared with adults. Infection is the most frequently documented cause (more than 40%) in children with acute urticaria. In a recent systematic review, viral infection was a potential trigger and sometimes the main cause in acute and chronic urticaria. The rate of identification of a specific cause in children with chronic urticaria varies from 20%-50%, but in practice, most patients have no precise causes and are classified as chronic idiopathic urticaria. The underlying causes of chronic spontaneous urticaria do not appear to be different between children and adults; however, their frequencies are different. In recent studies, more than 30% of children with chronic urticaria are classified as chronic autoimmune urticaria. Even though the prevalence is lower in children than in adults, nonsteroidal anti-inflammatory drugs are identified as major aggravating factors of chronic spontaneous urticaria in children. In the very recent studies of adults with chronic urticaria, serum vitamin D levels were likely to be lower and showed significant negative associations with urticaria activity score and duration. Furthermore, several studies have proposed that vitamin D plays a beneficial role in the treatment of adult chronic urticaria; however, the role of vitamin D is still controversial and it is unclear in children with chronic urticaria. Disease activity in spontaneous urticaria usually assessed with the urticaria activity score (UAS) for 7 days , and the recently provided guideline of chronic urticaria recommends use of the UAS for evaluating severity and guiding management. The UAS is based on the assessment of key urticaria symptoms (wheals and pruritus), and it is useful for assessing the urticaria activity by both patients and their physicians. In a previous study, it is estimated that up to 15%-25% of adults experience at least 1 episode of acute urticaria during their life time. A recent population-based questionnaire survey showed that the lifetime prevalence rate of urticaria in adults was 8.8% for all types of urticaria, whereas the prevalence of chronic urticaria in the general population has been estimated to range from 0.5% to 5%. Chronic urticaria in children is expected to be less common than in adults; however, the exact prevalence is unknown because reliable epidemiologic studies are scarce in children with chronic urticaria. In a recent population-based German birth cohort study, the incidence and cumulative prevalence of urticaria in infants and children were reported. The incidence of urticaria was approximately 1% per year of age and the cumulative prevalence of urticaria in children at the age of 10 years was 14.5% for boys and 16.2% for girls, but the prevalence of chronic urticaria was not evaluated separately. In the current issue of the Allergy, Asthma and Immunology Research, Lee et al. reported a valuable study on the prevalence and risk factors of acute and chronic urticaria in Korean children, and it is the first population-based epidemiological study to estimate the prevalence of chronic urticaria in children. This cross-sectional study examined children from the general pediPrevalence and Causes of Childhood Urticaria Meeyong Shin, Sooyoung Lee*