[Value of the intracutaneous skin test in analgesic intolerance in comparison with oral provocation]

A total of 24 patients showing predominantly urticarial and/or anaphylactic reactions to analgesics were exposed to the suspicious agents by means of skin testing and oral provocation. Only two patients, who had already shown mild anaphylactic symptoms during the skin test, were excluded from the oral provocation test. In 19 out of 24 cases, the presumed intolerance of analgesics could be confirmed by oral provocations, i.e., the rate of accuracy was 79%. Five patients tolerated the usual therapeutic single doses of previously suspicious agents, although 3 of them had shown positive skin tests. Two patients failed to show suspicious symptoms in both skin and oral provocation test. 14 patients reacted to propyphenazone, 6 patients to metamizole, and one patient each additionally to salicylamide or phenylbutazone. In the majority of the cases, parallel skin tests with all test agents were performed, using both aqueous suspension and the so-called serum linkage. Principally, both procedures proved equally good. In our patients, the skin tests (prick and intracutaneous test) were only reliable regarding the demonstration of propyphenazone allergy. 16 out of 19 patients showed the same reactions to both skin test and oral provocation (84%); in 3 cases, however, the skin tests to propyphenazone were false positive. The rate of accuracy in the metamizole skin test was 45%. With regard to the remaining suspicious agents, only 2 out of 6 positive skin tests were confirmed by oral provocation. In total, the numbers of true positive and false positive skin tests were almost equal. Thus, the demonstration of analgesic intolerance by history and skin test was only possible with a probability rate of 50%. By oral provocation, however, analgesic intolerance could be proved in almost 80% of the cases. Regarding the remaining 5 patients, we must assume that they were devoid of true analgesic allergy in spite of partly positive skin tests and apparently confirmative history.