Patch 1 (Expired): All enrolled participants will be simultaneously patch tested with both expired and non-expired patches. Therefore, there is no difference in intervention amongst study participants.
Patch 2 (non-expired): All enrolled participants will be simultaneously patch tested with both expired and non-expired patches. Therefore, there is no difference in intervention amongst study participants.
Study summary
Patch testing remains the gold standard in the diagnosis of allergic contact dermatitis. Patches used in testing consist of a wide spectrum of allergens, with variability in the stability of products over time. Due to limited allergen stability, careful storage and preparation is needed to prevent product degradation over time. Expiration dates are provided by manufacturers to ensure stability and reactivity, while minimizing the risk of product degradation contributing to inaccurate testing results. Preparation of patch series can be time intensive and procurement of allergens comes with an associated economic burden. Expired allergens are not routinely used in patch testing, however many clinics have expired allergens accessible. There is paucity of evidence comparing the reactivity of expired vs non-expired patch series. If expired allergens remain effective, this could result in significant cost-savings and accessibility implications for dermatology practice.
Eligibility
Sex
ALL
Min age
18 Years
Max age
—
Healthy volunteers
No
Inclusion Criteria:
* Adults (age 18 years or older) referred for patch testing.
Exclusion Criteria:
* Relative or absolute contraindication to patch testing
* Wide spread dermatitis prior to patch placement
* Inability to return to clinic for reading of results
* Patient non-consenting
Primary outcome measure(s)
Patch Testing Response (Positive/Negative) Concordance Rate (%) Between Non-Expired and Expired Allergens — Standard patch test series are applied on Day 0. Participant removal of patches on Day 2 and self photos taken and sent to Dermatologist for virtual reading. Final reading completed in clinic by Dermatologist on Day 4 or 5, recording reaction scores. Each allergen will be graded on response using a standard patch test scale including: irritant reaction \['IR'\], '+/-' for doubtful, '+' for erythema and infiltration, '++' for edematous or vesicular and '+++' for spreading, bullous or ulcerative response that will be graded by the participating Dermatologist. Reactions graded '+', "++", or "+++" are consider a positive result. Concordance rate will be expressed as a percentage (%) between tested allergens that were non-expired and that were expired (i.e. Nickel sulfate hexahydrate was found to have a 92% concordance rate, meaning that in 92% of cases, the Nickel allergen in the non-expired and expired patches were both found to both be either positive or negative while in 8% of cases the response differed per the scale listed above.)
This page summarises publicly available registry data for informational purposes — not medical advice. Eligibility is determined by each study team; patients should discuss participation with their clinician.
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