Skin testing in patients with hypersensitivity reactions to iodinated contrast media - a European multicenter study.
BACKGROUND
Iodinated contrast media cause both immediate and nonimmediate hypersensitivity reactions. The aim of this prospective study was to determine the specificity and sensitivity of skin tests in patients who have experienced such reactions.


METHODS
Skin prick, intradermal and patch tests with a series of contrast media were conducted in 220 patients with either immediate or nonimmediate reaction. Positive skin tests were defined according to internationally accepted guidelines. Seventy-one never-exposed subjects and 11 subjects who had tolerated contrast medium exposure, served as negative controls.


RESULTS
Skin test specificity was 96-100%. For tests conducted within the time period from 2 to 6 months after the reaction, up to 50% of immediate reactors and up to 47% of nonimmediate reactors were skin test positive. For immediate reactors, the intradermal tests were the most sensitive, whereas delayed intradermal tests in combination with patch tests were needed for optimal sensitivity in nonimmediate reactors. Contrast medium cross-reactivity was more common in the nonimmediate than in the immediate group. Interestingly, 49% of immediate and 52% of nonimmediate symptoms occurred in previously unexposed patients. Many of these patients were skin test positive, indicating that they were already sensitized at the time of first contrast medium exposure.


CONCLUSIONS
These data suggest that at least 50% of hypersensitivity reactions to contrast media are caused by an immunological mechanism. Skin testing appears to be a useful tool for diagnosis of contrast medium allergy and may play an important role in selection of a safe product in previous reactors.
Brockow
K
K
Department of Dermatology und Allergology Biederstein, Division Environmental Dermatology and Allergology Helmholtz Zentrum München/TUM, Technical University Munich, Munich, Germany.
Romano
A
A
Aberer
W
W
Bircher
A J
AJ
Barbaud
A
A
Bonadonna
P
P
Faria
E
E
Kanny
G
G
Lerch
M
M
Pichler
W J
WJ
Ring
J
J
Rodrigues Cernadas
J
J
Tomaz
E
E
Demoly
P
P
Christiansen
C
C
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003287:Contrast Media / Q000009:adverse effects*; D003429:Cross Reactions / Q000276:immunology; D004342:Drug Hypersensitivity / Q000175:diagnosis* / Q000209:etiology / Q000276:immunology; D005260:Female; D006801:Humans; D007455:Iodine / Q000009:adverse effects* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D012882:Skin Tests; D055815:Young Adult
D003287:Contrast Media; D007455:Iodine