Evaluation of the permanence of skin sensitization to allergens in patients with allergic contact dermatitis

Abstract

BACKGROUNDPatch tests are an efficient method to confirm the etiological diagnosis of allergic contact dermatitis. OBJECTIVES1) To determine the permanence of results between two tests performed with an interval of at least one year, in patients with allergic contact dermatitis; 2) To compare the positive results according to rates of intensity; 3) To evaluate the permanence of sensitization according to each substance that was tested. METHODSPatients with previous diagnosis of allergic contact dermatitis, confirmed by patch tests carried out between the years 2005 and 2008, underwent new testing, using the same methodology, and data was compared. RESULTSA total of 1470 results of both tests on 49 patients were analyzed. The negative results remained in the second test in a rate of 96%, and 4% became positive (+) without relevance to the clinical history. Moreover, moderately (++) and strongly (+++) positive results were also maintained in, respectively, 86% and 100%. Nevertheless, weakly (+) positive results became negative in 65%. By ignoring all weakly (+) positive tests, the calculation of Kappa Index of Agreement Statistics between the two tests showed a value of 0.88. CONCLUSIONPatch tests showed to be reliable for negative, moderately (++) positive and strongly (+++) positive results, by reproducing the same standard of individual response to allergens. However, for weakly (+) positive results, tests were not reliable.

Patch test results in children and adolescents. Study from the Santa Casa de Belo Horizonte Dermatology Clinic, Brazil, from 2003 to 2010

“…Given the high proportion of positive and relevant tests with reaction intensity 1+ (48/57; 84.2%), tests with intensity reaction 1+ were not excluded from the positive results of this study, although a recent study considered positive tests with intensity 1+ unreliable when compared in two tests, with an interval of 12-60 months in 49 patients. 45 …”

Early detection and persistent positivity of anti-Leishmania antibodies using a recombinant protein-based ELISA in naturally infected dogs in Brazil

“…While the literature contains longitudinal studies evaluating CVL diagnostic methods, none have attempted to assess the persistence of positive results in a longitudinal manner [ 30 – 32 ]. Importantly, other studies have evaluated the persistence of diagnostic test results in diseases other than leishmaniasis, such as allergic contact dermatitis, asthma and rheumatoid arthritis [ 33 – 35 ].…”

Patch tests

“…20 Positive (+ +) tests were reproduced in 86% of cases. Low intensity (+) tests did not show the same reliability.…”

“…Duarte et al ., in a recently published study, showed that high intensity (+ + and + + +) tests were fully reproduced when patients were retested within a year after the first test. 20 Positive (+ +) tests were reproduced in 86% of cases. Low intensity (+) tests did not show the same reliability.…”