Positive patch test reactions to nickel sulphate are not modified by neighbouring negative fragrance patch tests. A multicenter-study by the German contact dermatitis research group.
It is tacitly assumed that a positive patch test reaction is not affected by adjacent negative tests. However, despite its fundamental importance for the interpretation of test reactions this assumption has not been proven. To test this assumption, special TRUE-test strips were prepared containing placebo, nickel sulphate and fragrance mix as the only allergens, separated by distances of 1 cm and 7 cm and blinded to the investigators. Patients were synchronously tested with two strips. Out of 493 patients tested in 6 centres, the 93 with positive reactions to nickel sulphate only were evaluated. No relevant difference was found between positive nickel reactions in the two different distances to a negative fragrance patch test. We conclude that a positive patch test reaction is not affected by adjacent negative patch tests, which therefore can be neglected for the interpretation of positive reactions.
Brasch
Jochen
J
Department of Dermatology, University of Schleswig-Holstein, Campus Kiel, Germany. jbrasch@dermatology.uni-kiel.de
Weichenthal
Michael
M
Szliska
Christiane
C
Löffler
Harald
H
Koch
Patrick
P
Grabbe
Jörgen
J
Mahler
Vera
V
Kreilgård
Bo
B
Hoeck
Ulla
U
D000485:Allergens / Q000276:immunology*; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009532:Nickel / Q000276:immunology*; D010328:Patch Tests; D010476:Perfume
D000485:Allergens; D010476:Perfume; C029938:nickel sulfate; D009532:Nickel