Relationship between the atopy patch test and clinical expression of the disease in children with atopic eczema/dermatitis syndrome and respiratory symptoms.

BACKGROUND: The atopy patch test (APT) may be the only positive skin test result in patients with either atopic eczema/ dermatitis syndrome (AEDS) or respiratory abnormalities with or without AEDS. OBJECTIVE: To investigate the possible significance of APT to dust mite by comparing the positive result to this test with that of the skin prick test (SPT) in patients with different characteristics. METHODS: A total of 297 individuals (178 boys and 119 girls) aged 5 to 221 months (mean [SD] age, 64.5 [42.1] months; median age, 58 months) were included in this study. Participants were divided into 4 groups: current AEDS, current AEDS and respiratory symptoms, past AEDS and respiratory symptoms, and respiratory symptoms with neither current nor past AEDS (control group). All the patients underwent SPT and APT using house dust mite extract. RESULTS: In the study groups, the rate of positivity was significantly higher for APT, whereas in the control group, there were significantly more positive results to SPT (P < .001 for both). Multivariate analysis showed that there was a high probability of a positive APT result in patients with AEDS (odds ratio [OR], 17.4), with AEDS and respiratory disease (OR, 21.9), and with past AEDS and respiratory disease (OR, 22.8). CONCLUSIONS: These patients with AEDS showed 2 different patterns of allergic response to allergens, one IgE mediated (as evaluated by positive SPT results) and the other cell mediated (as evaluated by positive APT results). The former seems to follow the so-called atopic march model, and the latter persists even after the disappearance of AEDS and is likely to be implicated in the pathogenesis of respiratory allergy.