Prevalence of food avoidance and food allergy in Chinese patients with chronic urticaria

Background Food avoidance is common among Chinese patients with chronic urticaria because food allergy is considered to be the cause of disease. The benefit of food avoidance and its relationship with food allergy is unknown. Objectives The aims of this study were to examine the prevalence and effect of food avoidance and food allergy in patients with chronic urticaria. Methods Four hundred and ninety-four patients with chronic urticaria, who attended Peking University Third Hospital from January 2009 to December 2010, were studied. Food avoidance and its effect were investigated with a detailed questionnaire. Food allergy was diagnosed by serum food-specific immunoglobuhn E (IgE), elimination diet based on food-specific IgE, and open food challenge. Results One hundred and fifty-eight patients (32%) avoided fish, shrimp, crab, lamb or beef prior to evaluation and 82.9% of them reported food avoidance ineffective. Out of 341 patients tested for serum food-specific IgE, 75 (22%) were positive, with soy, peanut, beef, lamb, chicken, crab and shrimp as the leading allergens. Chronic urticaria induced by food allergy was found in only 2.8% of patients. Conclusions The prevalence of food avoidance is high and mostly ineffective in Chinese patients with chronic urticaria. Foods avoided do not correspond to serum food-specific IgE. The incidence of IgE-mediated urticaria, as demonstrated by open food challenge, is low. Physicians and patients should be aware of unnecessary dietary avoidance while seeking treatment of chronic urticaria,