PATCH TESTING WITH A COMBINATION OF UNRELATED ALLERGENS - A NEW STRATEGY

A simplified method of patch testing was designed, in which several to tally unrelated allergens were combined in each patch. The method was evaluated by double blind comparison of responses to 17 standard aller gens applied individually as 17 conventional patch tests, and as two d ifferent sets of Eve patches each containing combinations of three or four allergens per patch, in 137 patients under investigation for cont act allergic dermatitis. There were 89 positive responses to conventio nal patch testing with separate allergens and 94 and 86 positives to t he two different combinations of the same allergens. Concordance of po sitive reactions to the two combinations was 80% and there were no irr itant reactions, Conventional testing detected 70 and 74% of reactions to combination patches 1 and 2 and combination patches 1 and 2 detect ed 80 and 79% of the reactions to conventional testing, The combinatio ns detected clinically relevant sensitivities not found by conventiona l testing, Thus, combination patch testing appears to give consistent and reliable results; its use would reduce the number of patches and i ncrease the diagnostic yield for the specialist and permit preliminary screening by the general practitioner.