Reproducibility of patch tests. A multicenter study of synchronous left-versus right-sided patch tests by the German Contact Dermatitis Research Group.
BACKGROUND
The efficiency and reproducibility of patch tests remain controversial.


OBJECTIVE
Our purpose was to determine the efficiency and reproducibility of patch tests and to identify factors influencing these features.


METHODS
We double-tested 1285 patients concomitantly with 10 standard allergens by manually filled test chambers. Additional information was obtained from all patients with a standardized protocol.


RESULTS
Patch test efficiency was good (> or = 0.94) with all 10 allergens. In contrast, nonreproducibility of patch tests was strongly allergen dependent, ranging from 0.2 for nickel sulfate to 0.6 for formaldehyde. The likelihood of nonreproducible allergic reactions increased when more than four positive reactions were seen at the same time, and with another positive reaction located in close proximity to an allergic reaction. Sex and age of patients, atopy, dermatitis at distant sites, sleeping habits, and the time of allergen exposure (24 or 48 hours) did not affect the rate of nonreproducible results.


CONCLUSIONS
To increase patch test reproducibility, specific preparations of patch test allergens need to be improved. Furthermore, amplification effects by synchronous neighboring positive reactions should be excluded.
Brasch
J
J
Department of Dermatology, University of Kiel, Germany.
Henseler
T
T
Aberer
W
W
Bäuerle
G
G
Frosch
P J
PJ
Fuchs
T
T
Fünfstück
V
V
Kaiser
G
G
Lischka
G G
GG
Pilz
B
B
D000485:Allergens / Q000009:adverse effects; D015982:Bias; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis; D003876:Dermatitis, Atopic / Q000175:diagnosis; D003877:Dermatitis, Contact / Q000175:diagnosis*; D017453:Dermatitis, Irritant / Q000175:diagnosis; D005260:Female; D005557:Formaldehyde / Q000009:adverse effects; D005858:Germany; D006801:Humans; D007509:Irritants / Q000009:adverse effects; D008297:Male; D009532:Nickel / Q000009:adverse effects; D010328:Patch Tests / Q000706:statistics & numerical data*; D010655:Phenylenediamines / Q000009:adverse effects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors
D000485:Allergens; D007509:Irritants; D010655:Phenylenediamines; D005557:Formaldehyde; C029938:nickel sulfate; D009532:Nickel; C029728:4-phenylenediamine