The sensitivity of a test is its ability to detect an allergic contact eczema. It allows to assess the risk of false negative reactions.
The specificity of a test is its ability to ensure a discrimination between allergic reaction and irritation reaction. It allows to assess the risk of false positive reactions.
The goal in any developed dermato-allergic is the determination of the relevance of the results.
The current relevance which is to establish a link between the results of positive tests for allergic nature and pathology presented recently by the patient;
Former relevance which is to establish a link between the results of positive tests for allergic nature and a former pathology, without any relationship with developed lesions recently by the patient.
The results of the tests has an interest in this perspective, since they then allow only to draw practical conclusions from the point of view diagnostic, therapeutic and preventive.
The determination of relevance is in some easy cases and other much more complex. All varieties of tests that have been cited in the previous pages may contribute to this determination.
Sometimes the positive patch testing allergic in nature sufficient to support the relevance. In other cases, on the contrary, they must be confirmed by further tests (iterative open tests, tests of use etc.).