title: A multicentre study to determine the value and safety of drug patch tests for the three main classes of severe cutaneous adverse drug reactions.
abstract: BACKGROUND
  Drug patch tests (PTs) can reproduce delayed hypersensitivity to drugs and entail a moderate re-exposure of patients to offending drugs.
  
  
  OBJECTIVE
  To determine the value of PTs for identifying the responsible drug in severe cutaneous adverse drug reactions (SCARs) such as acute generalized exanthematous pustulosis (AGEP), drug reaction with eosinophilia and systemic symptoms (DRESS) and Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN).
  
  
  METHODS
  In a multicentre study, PTs were conducted on patients referred for DRESS, AGEP or SJS/TEN within 1 year of their SCAR. All drugs administered in the 2 months prior to and the week following the onset of the SCAR were tested.
  
  
  RESULTS
  Among the 134 patients included (48 male, 86 female; mean age 51·7 years), positive drug PTs were obtained for 24 different drugs. These included positive tests for 64% (46/72) of patients with DRESS, 58% (26/45) of those with AGEP and 24% (4/17) of those with SJS/TEN, with only one relapse of AGEP. The value of PTs depended on the type of drug and the type of SCAR (e.g. carbamazepine was positive in 11/13 DRESS cases but none of the five SJS/TEN cases). PTs were frequently positive for beta lactams (22 cases), pristinamycin (11 cases) and in DRESS with pump proton inhibitors (five cases), but were usually negative for allopurinol and salazopyrin. Of 18 patients with DRESS, eight had virus reactivation and positive PTs. In DRESS, multiple drug reactivity was frequent (18% of cases), with patients remaining sensitized many years later.
  
  
  CONCLUSIONS
  PTs are useful and safe for identifying agents inducing SCAR.
authors.affiliation: Dermatology Department, University Hospital of Nancy, Pôle des Spécialités Médicales, Université de Lorraine, Brabois Hospital, 6 Rue du Morvan, Vandoeuvre-lès-Nancy 54500, France. a.barbaud@chu-nancy.fr
authors.forename: A
authors.initials: A
authors.lastname: Barbaud
authors.forename: E
authors.initials: E
authors.lastname: Collet
authors.forename: B
authors.initials: B
authors.lastname: Milpied
authors.forename: H
authors.initials: H
authors.lastname: Assier
authors.forename: D
authors.initials: D
authors.lastname: Staumont
authors.forename: M
authors.initials: M
authors.lastname: Avenel-Audran
authors.forename: A
authors.initials: A
authors.lastname: Grange
authors.forename: S
authors.initials: S
authors.lastname: Amarger
authors.forename: P
authors.initials: P
authors.lastname: Girardin
authors.forename: M-T
authors.initials: MT
authors.lastname: Guinnepain
authors.forename: F
authors.initials: F
authors.lastname: Truchetet
authors.forename: A
authors.initials: A
authors.lastname: Lasek
authors.forename: J
authors.initials: J
authors.lastname: Waton
mesh_terms: D056150:Acute Generalized Exanthematous Pustulosis / Q000139:chemically induced; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003875:Drug Eruptions / Q000175:diagnosis* / Q000209:etiology; D004347:Drug Interactions; D004802:Eosinophilia / Q000139:chemically induced; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010328:Patch Tests / Q000009:adverse effects / Q000379:methods; D013262:Stevens-Johnson Syndrome / Q000139:chemically induced / Q000209:etiology; D013997:Time Factors; D055815:Young Adult