Inherent clinical properties of non-immediate hypersensitivity to iodinated contrast media

Iodinated contrast media (ICM) is a frequently used compound in radiology. Non-immediate hypersensitivity reactions (HSR) appear when a patient leaves the department and usually are undocumented. True hypersensitivity in this group is rarely proved.

Single-centre 2014-2018 data were retrospectively analysed. HSR to ICM were classified and investigated according to the time of occurrence (immediate <1 hour, non-immediate >1 hour). ENDA questionnaire and skin tests (prick or intradermal test) were performed according to ENDA/EAACI recommendations.

69 patients with a clinical history of HSR to ICM were identified, 72.46% were females (n = 50). The average age was 56 (SD ± 13.16) years. Non-immediate HSR occurred in 28.99% (n = 20) patients. The suspected culprit drugs were: iodixanol 20% (n = 4), iopromide 5% (n = 1), diatrizoate 10% (n = 2) and iohexol 10% (n = 2). Among non-immediate HSR 96.00% (n = 19) of patients had skin rashes. A statistically significant correlation was found between the clinical symptoms and the type of reaction (p-value <0.05): isolated skin manifestations mostly occurred in non-immediate HSR 75.00% (n = 15). Only 13.04% (n = 9) of all the patients were proved to be allergic to a certain ICM after the proposed diagnostic workup.

One-third of the hypersensitivity reactions investigated were classified as non-immediate type. Most of them manifested with isolated skin symptoms. The most frequent culprit drug encountered was iodixanol. The overall non-immediate hypersensitivity confirmation rate after diagnostic evaluation was only 15%.