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 i dentified with patch testing, use tests (provocative use test (PUT), and re peated open application test (ROAT)) have been used. In 1/2 of the cases of seemingly reliable patch tests, use tests are negative, suggesting that th e patient's biologic threshold of response had not been reached with open a pplication dosing. Dramatic differences exist in regional skin reactivity a nd percutaneous penetration. Negative results of use tests on normal skin m ay become positive on diseased skin. To refine this assay further, more con trolled observations and analysis of reaction differences between normal an d damaged skin, and among regional anatomic sites might be performed. In ad dition, 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 def iciencies described above.