Comparison of diagnostic tests for suspected cow's milk allergy in children with atopic dermatitis.

Background: Atopic dermatitis (AD) is a chronic inflammatory skin disease. A third of pediatric AD patients have also food allergy. Although food challenge test is gold standard test for the diagnosis of food allergies, they should be administered by experienced physicians, considering that the test is time-consuming and carries some risks. Documentation of the efficacies of specific IgE (sIgE), skin prick test (SPT), and atopy patch test (APT) are important for determining the necessity of oral food challenge tests(OFC).

Methods: Fifty-three AD patients with suspected cow's milk allergy (CMA) were included in our study. Diet-related questions were asked to the patients. Blood samples were taken for measurement of total blood count, total IgE, and milk sIgE. OFC, SPT, and APT were performed using pasteurized cow milk.

Results: The mean age of the study population was 1.4±0.8 years, and the male:female ratio was 1.12. Cow milk allergy was detected in 45.3% of the patients after OFC. A comparison between CMA(+) and CMA(-) patients revealed no significant difference in sIgE positivity (P=0.940), but there was a significant difference in SPT (P=0.000) and APT (P=0.001) positivity. When our study group was divided into immediate reaction, delayed onset reaction, and not reactive subgroups after OFC, efficacy of SPT was more prominent in immediate reaction subgroup while APT was more efficient in delayed reaction subgroup.

Conclusions: Our study showed that using SPT test with APT test in allergic reactions with IgE and other mechanisms such as AD will increase the diagnostic yield, thereby reducing the need for OFC.