Aetiological factors associated with chronic urticaria in children: a systematic review.

Chronic urticaria is a distressing condition with high costs. The aim of this literature review was to assess the relative frequency of causes of chronic urticaria in childhood and to provide guidance on which laboratory tests should be performed. Using PubMed, EMBASE and Cochrane databases, the literature from 1966 to 2010 (week 25) was systematically reviewed. Data from studies conducted on children who had had urticaria for at least 6 weeks, and assessing at least 3 different causes of urticaria, were analysed by reviewers using independent extraction. Six studies, all of low quality, met the inclusion criteria. Idiopathic and physical urticaria were common. Infections, autoimmunity and allergy were also reported. We conclude that children with chronic urticaria not caused by physical stimuli should undergo tests for allergy or infections only when there is a history of cause-effect correlation. High-quality trials are warranted to evaluate the causes of chronic urticaria in childhood.