“New” techniques for more sensitive patch testing?

Abstract

The patch test is the mainstay of diagnosis in allergic contact dermatitis. In its nearly 120-year-long history, numerous efforts to standardize several methodical aspects proved successful. The aim was always to enhance the validity and reliability of patch testing. This article reviews modifications of the basic patch test technique for enhancing test sensitivity. We expand on the recently validated strip patch test, which is a modification that involves affixing tape strips to the skin and removing them prior to patch testing. Although it was first described in 1953, we proposed the first protocol for standardized performance of the "strip patch test." The protocol was then tested in studies. As a result, test sensitivity of standardized strip patch test versus patch test was increased. The protocol produced a uniform reduction in the thickness of the stratum corneum and a good inter-rater agreement. Additionally, there was evidence of a non-specific stimulation of the inflammatory epidermal system. With regard to patient history, the standardized strip patch test showed a vastly better sensitivity than the patch test with only marginally lower specificity. As a complementary measure to patch testing diagnostic accuracy could be improved significantly by performing the standardized strip patch test. Further studies are needed on the reproducibility of the standardized strip patch test.