Italian multicenter study on Epiquick®, Rapid Patch Test® and TRUE TestTM⋆

Using 3 different ready-to-apply patch test systems (Epiquick®= EPI; Rapid Patch Test®= RPT; TRUE TestTM= TT), 316 patients sensitive to at least one allergen were studied in order to investigate the reproducibility of these tests in comparison with the Finn Chamber ®(FC) technique. Each patient was tested with a different ready-to-use system. Each test was compared to the same allergen applied with FC to either side of the upper back. Comparisons were made using EPI, RPT, and TT in 93 (183 tests), 119 (262 tests), and 104 (242 tests) patients respectively. When a positive test result occurred on only one side of the back, the concordance was defined as negative. Similarly, doubtful reactions on either side corresponding to positive or negative results were considered as non concordant. The concordance of positive reactions was 80.9% between the EPI and the FC technique, 77.5% between the RPT and the FC technique, and 72.3% between the TT and the FC technique. The frequency of questionable (+?) and irritant reactions (IR) was about the same for the different tests. Nevertheless, when comparing the positive reactions vs +?, IR, or negative reactions in paired tests, positive results were more frequently obtained with the FC technique. Our data suggest that the standard method with FC allows a better detection of contact allergy than the new ready-to-use systems tested in this study.