Drug re-challenges in cutaneous adverse drug reactions: information and effectiveness in the long-term management of patients

BACKGROUND: In patients with cutaneous adverse drug reactions (CADR), drug skin tests and re-challenge under hospital surveillance (RCH) are helpful. The aim of this study was to determine if patients with negative drug RCH can tolerate subsequent treatments with the same drugs. PATIENTS AND METHODS: Patients with a negative RCH in the last 10 years answered a telephone questionnaire which was delivered by the same investigator in order to determine if subsequently the patients were able to tolerate the drug with which they had a negative RCH and also to study the reasons why the drugs were not taken again. RESULTS: Six hundred and thirty-seven RCH were analyzed (349 patients, mean age 47 years), 134 drugs were taken again (group A) and 359 were not (group B). In group A, 12 reactions occurred in 10 patients (9%). In group B, drugs were not taken again because 76% of the patients evaluated for an intolerance to antibiotics or radiocontrast media did not require a new course of these products or because their general practitioner (GP) did not want to prescribe these drugs. DISCUSSION: Ninety percent of the RCH (88.5% of the patients) with a CADR followed by investigations and a RCH have a good tolerance to subsequent treatment with the RC drug. The mechanisms involved in this intolerance despite negative RCH are discussed. CONCLUSION: The provocation test procedure, considered as useful by 88% of the patients, has a good negative predictive value. Furthermore, these investigations need to be accompanied by clear information on the patient and his GP.