to the editor: I enjoyed reading the recent review article, “Allergy Testing.”1 The article provided useful and timely information, especially with the increasing incidence of asthma and other atopic diseases in the United States. However, the article did not fully describe the relevance and benefits of testing for food allergies.
Some evidence supports Dr. Li's statements that “percutaneous skin testing … is less reliable for evaluating food allergy than for evaluating reaction to airborne allergens” and that “a double-blind food challenge should be considered when more clinical certainty is needed in diagnosing a serious food allergy.” However, evidence also suggests that hypoallergenic diets are clinically useful for patients with atopic disease. In one study,2 91 percent of 322 children placed on a hypoallergenic diet had significant improvements in asthma or allergic rhinitis; food challenges reproduced symptoms 51 percent of the time, but skin tests with food allergens rarely correlated with these results. In another trial,3 41 adults with severe asthma were randomized to either an antigen-free elemental diet or a control diet (both composed of blended food) under double-blind conditions. Patients treated with the elemental diet had significant improvement in their asthma scores.
These data support the hypothesis that food allergy is a significant component of atopic disease in some patients and also that challenge testing is superior to skin antigen testing. The diagnosis and treatment of both food and respiratory allergies is clinically useful, and we should be aware of any modalities that may benefit our patients.