Usefulness of skin testing in cutaneous drug eruptions in routine practice.

ABSTRACT

BACKGROUND: Cutaneous drug eruptions are common side-effects. The imputation score combining intrinsic (chronology, clinical and paraclinical signs) and extrinsic criteria used in Pharmacovigilance Centres is insufficient alone to identify with certainty a responsible drug. OBJECTIVE: To evaluate the imputation score before and after performing skin testing in patients with cutaneous drug eruptions. PATIENTS/METHODS: A single-centre retrospective study was performed on 339 patients tested between 2001-2006. Imputation scores were calculated before and after skin tests for each cutaneous drug eruption according to the clinical type of skin eruption and the type of drug. RESULTS: Among 121 patients meeting inclusion criteria, 46% showed an increase of the imputation score as shown by 25/41 cases of maculo-papular exanthema, 4/11 cases of acute generalized exanthematous pustulosis and 17/41 cases of urticaria/anaphylaxis. The imputation score increased in 25/70 cases of the tested antibiotic drugs, in 14/56 cases of cardiovascular drugs, and it increased in 19 patients (34%) with I1 or I2 imputation scores before skin testing and in 29 (52%) with an I3 imputation score before skin testing. CONCLUSIONS: Drug skin testing appeared useful in investigating cutaneous drug eruptions in routine practice, including not only drugs with a high imputation score (I3) but also those with a lower score (I1, I2). Drug skin testing should lead to oral rechallenge of drugs with negative tests in order to determine which drugs may be used safely.