Background and objectives: Patch testing with commercially available kits detects only 70-80% of relevant allergens in patients with contact dermatitis. This is not ideal, especially when occupational issues are being evaluated. This study analyses our data regarding reactions to patients' own products.
Methods: In a 5-year period, 1532 patients were assessed in our occupational dermatology clinic.
Results: We found that 101 patients (6.6%) reacted to their own samples. In 20 (1.3%) cases, reacting to their own samples was the only clue for detecting the responsible allergen. In 59 (3.9%) cases, testing with their own samples reinforced their reactions to commercial allergens.
Conclusions: We found the overall additive value of testing with patients' own products to be 5.2%. This is not a low proportion considering the 20-30% false negative rate when patch testing. Patch testing with patients' own samples, appropriately diluted should be undertaken whenever possible.