Positive reactions to gold sodium thiosulfate in patch test panels (TRUE Test) in Japan: A multicentre study

Background The proportion of positive test results with gold sodium thiosulfate included in a patch test panel (P-GST) had been found to be greater than that with gold sodium thiosulfate 0.5% pet. by allergEAZE (A-GST). Objectives To compare positive reactions to P-GST and A-GST, and to evaluate late reactions after the day (D) 7 reading. Methods A retrospective analysis was performed of 588 patients at participating departments (119 males; 469 females) who were patch tested with P-GST and A-GST in May 2015 to March 2016. Results Positive test reactions to P-GST and A-GST were observed in 15% and 6% of patients, respectively. Three patients reported a positive reaction occurring after the D7 reading. Conclusions Gold sodium thiosulfate often gives a positive reaction after 2 to 3 weeks, and, in such cases, the positive reaction may be sustained, so it is recommended to assess the reaction for up to 1 month after application.