Dose/area and reading paradigms for gold patch testing are controversial and not standardized worldwide.
The aims of this study were to determine the optimum patch test dose of gold sodium thiosulfate (GST) in a hydrogel (HYD) and to establish GST HYD safety/efficacy and further characterize normal morphology and time course of GST reactions.
Twenty gold-allergic patients were patch tested with a dilution series of GST HYD and with GST 2% petrolatum (pet). Furthermore, this previously determined optimal dose was compared with GST 0.5% pet in 19 known-allergic and 216 consecutive subjects.
The optimal GST HYD dose was 0.075 mg/cm2, not statistically different from GST 2% pet (P = 0.4795). Gold sodium thiosulfate HYD outperformed GST 0.5% pet in both known-allergic subjects (79% vs 63%, P = 0.2482) and consecutive subjects (30% vs 9%, P < 0.0001). Late reactions were common in consecutive patients with both HYD and pet. Significantly more persistent reactions were associated with GST HYD than with GST 0.5% pet.
Gold sodium thiosulfate HYD 0.075 mg/cm2 is the optimal dose for diagnosis of gold contact allergy with GST. Gold sodium thiosulfate 0.5% pet yielded false-negatives in some patients, suggesting inadequate dose per centimeter squared. Late reads are normal, expected, and necessary for diagnosis of gold contact allergy in this cohort.
From the *Division of Dermatology, Department of Medicine, The Ohio State University, Columbus;
†Contact Dermatitis Institute, Phoenix, AZ;
‡Department of Occupational and Environmental Dermatology, Lund University, Ska˙ne University Hospital, Malmö, Sweden;
§Division of Dermatology, University of Louisville School of Medicine, KY;
∥Department of Dermatology and Allergy, Herlev and Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; and
¶Department of Dermatology and Allergy Centre, Odense University Hospital, and Dermatological Investigations Scandinavia, Department of Clinical Research, University of Southern Denmark, Denmark.
Address reprint requests to Dathan Hamann, MD, Division of Dermatology, Department of Medicine, The Ohio State University, 764 S 3rd St, Columbus, OH 43206. E-mail: firstname.lastname@example.org.
The authors have no funding or conflicts of interest to declare.
This study was funded by a grant from SmartPractice.
C.P.H. is chief executive officer and owner of SmartPractice (Phoenix, AZ), a company that produces and sells patch testing materials including T.R.U.E. Test, and medical director of the Contact Dermatitis Institute; Drs. C.R.H. and D.H. are his sons but have no ownership or other interests to declare. K.E.A. is the medical advisor for SmartPractice Denmark. M.B. has lectured at a patch test course arranged by SmartPractice. J.F.F. is a consultant for SmartPractice.
Author Contributions: C.P.H., D.H., and K.E.A. had full access to all data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: C.P.H., M.B., C.R.H., K.E.A. Acquisition, analysis, and interpretation of data: all authors. Drafting of the manuscript: D.H., C.R.H. Critical revision of the manuscript for important intellectual content: all authors. Statistical analysis: D.H., M.B. Administrative, technical, or material support: all authors. Study supervision: all authors.
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