COADEX classification

A positive patch test (indicating contact allergy) is not necessarily a positive diagnosis of allergic contact dermatitis as indicated by the fact that some patients with a positive patch result never experience clinical symptoms after exposure to the test agent. The so-called COADEX classification is useful in the attempt to assess relevance of positive patch tests. COADEX stands for ... 

The COADEX classification should be used to assess clinical relevance of positive patch tests. Assays for drug-specific serum IgE antibodies are useful in cases of skin test-negative or equivocal reactors or when skin tests are unreliable or unavailable. 

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