Epicutaneous and Drug Provocation Testing in Severe Cutaneous Adverse Reactions: A 20-Year Single-Centre Experience

Identifying and discontinuing the offending drug(s) in severe cutaneous adverse drug reactions (SCARs) can be particularly challenging, especially in polymedicated patients. For many years, patch tests (PTs) were considered the only safe and reliable method for investigating SCARs. However, intradermal tests (IDTs), once thought to be contraindicated, have recently garnered increasing interest. Similarly, oral provocation tests, previously avoided due to safety concerns, are now being more frequently employed in SCAR assessment.

We analysed SCARs reported at Monastir University Hospital. Allergy work-up included PTs, IDTs and oral provocation tests, with evaluation of cross-reactivity, co-sensitisation and neo-sensitization.

We identified 190 SCAR episodes in 188 patients. DRESS was most frequent (75%), followed by AGEP (19%) and SJS/TEN (6%). Causative drugs were identified in 97.9% of cases, mainly anti-infectives. Skin tests were conducted in 69.5% of patients, yielding positivity rates of 49% for PTs and 77% for IDTs in DRESS, and 52% and 66%, respectively, in AGEP. Cross-reactivity was noted in 7% of DRESS and 11.1% of AGEP, while neo-sensitization was documented in 32.5% of DRESS patients.

Allergological investigations are valuable tools in SCAR management, enabling identification of culprit drugs, assessment of cross-reactivity, detection of neo-sensitization and selecting safe alternatives.