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- Presentation
What to do when patch test is negative: Making the best of your test and allergen selection
Description
The talk focuses on steps to take when a patch test for allergic contact dermatitis yields negative results. It is divided into four key steps: reconsidering testing, revisiting patient history, considering additional testing, and reassessing diagnosis. The speaker highlights that while patch testing is a gold standard, it is not infallible, with a sensitivity of 66% and specificity of 94%. Important factors for optimal testing conditions include checking allergen condition and concentration, ensuring proper application technique, and evaluating patient factors such as the presence of active dermatitis or prior UV exposure. They emphasize the need for thorough patient history to identify possible allergens not previously tested, suggesting repeat testing with extended series where necessary, especially for allergens like acrylates or fragrances. Additionally, they provide methods for conducting repeat open application testing and strip patch testing to explore individual reactions to allergens. The presenter advises against overly relying on initial patch test results and encourages a systematic reassessment of testing conditions and patient histories to ensure accurate diagnosis and treatment.
View moreConclusions
- Patch testing is a valuable but imperfect tool for assessing allergic contact dermatitis, with a sensitivity of about 66% and specificity of 94%.
- Negative patch test results require thorough reconsideration of testing conditions including allergen storage, application technique, and patient factors.
- Optimal allergen handling and preparation are crucial for accurate patch testing results.
- Patient education on preparation and adherence can improve testing outcomes.
- Revisiting patient history is essential to identify alternative exposure sources not covered by initial testing.
- Additional testing with extended allergen series or repeat open application testing is recommended when initial patch tests return negative.
- Some allergens, particularly methylisothiazolinone and various fragrance compounds, require specialized testing approaches to avoid missing significant allergies.
- Delayed reading of patch test results is necessary to capture potential positive reactions that might occur later, potentially identifying up to 30% more relevant allergies.
- J Allergy Clin Immunol. 2012;129(2):AB38
- Dermatitis. 2013 Sep-Oct;24(5):227-36
- Contact Dermatitis. 2015.
- J Allergy Clin Immunol Pract. 2015; doi:10.1016/j.jaip.2015.02.009
- An Bras Dermatol. 2013;88(6):879-888
- Arch Dermatolog Res 2004. 296:212-219
- Exog Dermatol. 2003;2:270-276
- Am J Contact Dermat. 2000;11(4):213-217
- Clinics in Dermatology. 39 (4), 2021, p580-590
- JAMA Dermatol. 2016;152(1):67-72
- Indian Dermatol Online J. 2016 Jan-Feb; 7(1): 12-16.