Comparison of validity of in-vitro testing, skin test and oral provocationin patients with hypersensitivity to acetylsalicylic acid

The investigation of hypersensitivity reactions to non-steroidal anti-infla mmatory drugs (NSAID) is of considerable importance in allergological pract ice. The aim of this study was to investigate the validity of in-vitro test ing, skin test and oral provocation in patients with a history of intoleran ce to acetylsalicylic acid (ASS). 47 patients were included in the study; 3 2 patients had an anaphylactoid reaction grade I (according to Ring & Messm er), 10 patients a grade II anaphylactoid reaction, and 5 patients a maculo papular rash after intake of ASS. In all 47 patients, serum was investigate d for IgE antibodies (RAST) against ASS (Hytec automated EIA system; Hycor Biomedical). 35 patients agreed to hospitalisation for skin testing and ora l provocation. Only 5 out of 25 patients with a history of grade I anaphyla ctoid reaction showed a positive skin test, one of these 5 patients showed a positive oral provocation. 5 out of 20 patients with a negative skin test were found positive in oral provocation. 1 out of 6 patients with grade II anaphylactoid reaction showed a positive skin rest and a positive oral pro vocation. None of the 5 patients with a maculopapular rash showed a positiv e skin test or oral provocation. Specific IgE antibodies to ASS could be de monstrated in none of the 47 patients. We conclude that the diagnosis of in tolerance to ASS should be based on careful study of the patients' history and in doubtful cases may be supported by oral provocation under adequate s afety precautions. In vitro testing for IgE antibodies specific to ASS is n ot useful.