EVALUATION OF PATCH TEST-RESULTS BY USE OF THE REACTION INDEX - AN ANALYSIS OF DATA RECORDED BY THE INFORMATION-NETWORK-OF-DEPARTMENTS-OF-DERMATOLOGY (IVDK)

Results of patch tests performed in 15,553 patients by 18 dermatologic al departments (members of the German Contact Dermatitis Research Grou p) and recorded by the Information Network of Departments of Dermatolo gy (IVDK) were analysed by comparing recently defined reaction indices (RIs). The RIs studied were calculated from the numbers of allergic ( a), questionable (q), and irritant (i) reactions (RI=(a-q-i/(a+q+i)), which were obtained using 13 European standard allergens. RIs were cal culated for all patients and for separate subgroups defined by age, se x, history of atopic dermatitis, time of allergen exposure (1 versus 2 days), and time of patch test reading (2 or 3 days after allergen app lication). Higher RIs were consistently obtained when patch tests were applied for 1 day, as compared to 2 days. Readings at 3 days after al lergen application resulted in higher RIs than readings after 2 days. In contrast, sex, age, and history of atopic dermatitis of patients we re not found to have a consistent influence on the RIs. We suggest tha t reading after 3 days should be obligatory, and that allergen exposur e for 1 day instead of 2 days mig ht make patch test evaluation easier . These suggestions need to be substantiated by data on clinical relev ance.