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Reproducibility of patch test results: a concurrent right-versus-left study using TRUE Test
1Department of Dermatology, School of Medicine, University of Uruguay, Arazati 1194, PC 11300, Montevideo, Uruguay. irisale@hc.edu.uy
Contact Dermatitis
|June 24, 2004
Summary
Patch testing is a reproducible diagnostic method for allergic contact dermatitis when standardized procedures are followed. Minimizing methodological errors significantly improves the reliability of patch test results in clinical practice.
Area of Science:
- Dermatology
- Allergology
- Contact Dermatitis Research
Background:
- Reproducibility of positive patch test responses varies widely in clinical practice.
- Methodological pitfalls in routine patch testing are suspected as a primary cause of inconsistent results.
Purpose of the Study:
- To investigate the reproducibility of patch test responses.
- To identify the impact of methodological rigor on the reliability of patch testing.
Main Methods:
- Simultaneous duplicate patch testing on opposite sides of the back in 500 patients.
- Utilized the TRUE Test system with 2 panels, each containing 12 standard allergens.
- Applied a rigorous methodology and assessed the relevance of discordant reactions.
Main Results:
- 58.8% of patients had positive patch tests; 5% of these reactions were discordant (positive on one side, negative/doubtful on the other).
- Nickel sulfate, cobalt chloride, and lanolin alcohol were common allergens in discordant reactions.
- 1.8% of all patients and 3.1% of those with positive tests had discordant allergens of definite relevance.
Conclusions:
- Patch testing is a reasonably reproducible diagnostic procedure.
- Minimizing methodological errors is crucial for enhancing the reliability of patch test results.