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5 Years INSTAND-ring tests for in-vitro allergy diagnosis – A contribution for quality assurance in medical diagnosis

Autoren:

  • Schellenberg, I.
  • Göring, H.-D.
  • Kabrodt, K.

Veröffentlicht in: Allergologie, Volume 26, Issue 1, 1 January 2003, Pages 1-14

The authors have been leading a team from the Institute of Standardization and Quality Control in Medical Laboratories (INSTAND) conducting ring tests into in vitro allergy diagnosis on behalf of the Federal Chamber of Medical Practitioners since 1995. The aim of the program was to test the comparability of results of specific IgE results against inhalation and food allergens in different laboratories. To date, 190 laboratories have taken part in ring tests and have determined specific IgE antibodies against the following allergens: birch pollen, dust mites, cat and dog, chicken protein, proteins in cow milk, bee and wasp venom, soya, celery, mugwort, apple and carrot. All the results were compared with each other. Those participating in the ring test were informed of the allergens the specific antibodies were aimed at. Their task was to determine the „RAST classes“ (as known RAST tests are used anymore. In this article, the word „RAST classes“ will be used because it is generally handled in the official allergologic doctor offices) and the IgE concentrations (kU/l). While all RAST results were simply compared with one another, the concentrations were compared on the basis of an area of 25% either side of the average IgE results. The results were also studied according to the testing systems and equipment used. The RAST classes were generally comparable among the individual companies represented by the participants. One negative result was the differing classification (RAST 0-4) of specific IgE antibodies in every group of participants independent of the company, including those against bee and wasp venom. There were clear differences when the results in kU/l were compared. In our opinion the differing results with specific IgE are linked to a specific laboratory’s experience in the field. Our results show that ring testing is essential to check the quality of in vitro allergy diagnosis. Quality can only be improved by discussing ring test results with the laboratories themselves as well as the test and equipment manufacturers. As a result of our investigations, we urgently recommend participation in ring testing and internal quality assessment.