Discussion
Chronic urticaria is a common medical condition, well-described in the adult population. Data regarding CSU in children is scarce. In the current report, we aimed to better characterize this disorder in a large cohort of children with a long follow-up period. We found that pediatric CSU is frequently accompanied by atopic diseases and has a favorable outcome.
The study cohort had an encouraging clinical course. CSU was not accompanied by angioedema in most children and there was a good clinical response to regular doses of antihistamines, without need for additional medications. In most cases, hives persisted for no longer than two years and relapses were rare. These findings are supported by previous smaller series that found CSU in children is a disease with good prognosis.2,9,13 In accordance with the favorable outcome, laboratory tests in our cohort were within the normal range. Probably, indicating that routine laboratory tests in children with CSU are not essential. This notion is supported by Grattan et al. who left the decision to perform laboratory tests in cases of CSU to the discretion of the treating physician.4
Traditionally, CSU is considered a disease of unknown etiology. Nonetheless, in some patients, an underlining autoimmune mechanism may be present. This concept is supported by the fact that, in adults, autoimmune diseases, mostly affecting the thyroid gland, frequently accompany CSU.6 Moreover, a canonic work by Hide et al. 32 reported autoantibodies against IgE and its receptor, as a potential trigger for the disease. These findings established the notion that CSU is a TH1 derived phenomenon. Atopy, including AD, AR, food allergy and asthma are considered TH2-related diseases. In the current study, one-third of the children with CSU had at least one atopic disease. AD and AR were significantly more prevalent in children with CSU, as compared to the general pediatric population in Israel and in the world. Food allergy was significantly more prevalent in children ages 4 to 12 years, with CSU, as compared to the general pediatric population. An exception is the difference in the prevalence of asthma; although higher in children with CSU than in the general pediatric population, it did not reach significance.
It can be speculated that the high prevalence of atopic comorbidities can be attributed, in part, to confusion between CSU and AD. When patients with AD were excluded from the analysis, the prevalence of other atopic diseases and the significant differences between patients with CSU and the general pediatric population remained similar.
High levels of IgE were found in more than half of the results. This finding did not overlap with the patients with clinical atopy. This laboratory abnormality might provide additional support to the underling atopic background accompanying these children.
The co-existence of atopic diseases had no effect on the likelihood of relapsing or on the duration of CSU. These findings are in concordance with other studies that showed a similar prevalence of atopic diseases in smaller cohorts of pediatric patients with CSU.5,8,9 Recently, one large cohort, that included Israeli adolescents, showed a robust link between CSU and atopic diseases.7 These publications all support the assumption that there is a subgroup of CSU patients with TH2-driven disease.
This study is subject to the limitations inherent to any retrospective work; some of the data were incomplete. As the follow-up period was very long, changes in the treatment modalities for CSU were inevitable. Treatment with anti-IgE was approved for children with CSU older than 12 years of age, only at the end of the follow-up period. As such, its effect on childhood CSU was not evaluated in this study.
In conclusion, CSU in children is mostly a mild disease. It does not tend to relapse and can be managed with antihistamines alone. Atopy was found to be prevalent in children with CSU. However, these atopic diseases did not influence the duration or severity of the disease. Whether CSU in children should be part of the spectrum of atopic diseases requires further investigation in larger, prospective studies.