Use tests: ROAT (repeated open application test)/PUT (provocative use test): an overview.

As one step in defining the clinical relevance of exposure to an allergen identified with patch testing, use tests (provocative use test (PUT), and repeated open application test (ROAT)) have been used. In 1/2 of the cases of seemingly reliable patch tests, use tests are negative, suggesting that the patient's biologic threshold of response had not been reached with open application dosing. Dramatic differences exist in regional skin reactivity and percutaneous penetration. Negative results of use tests on normal skin may become positive on diseased skin. To refine this assay further, more controlled observations and analysis of reaction differences between normal and damaged skin, and among regional anatomic sites might be performed. In addition, we require a standardized measurement for the results. Use testing has significant potential in refinement of the evidence-based diagnosis of clinical relevance. However, for general validation, we should fill the deficiencies described above.