Published online: May 9, 2019
Hypersensitivity reactions to iodinated contrast media (ICM) is a persistent clinical issue with the increased use of computed tomography. In contrast to the traditional concept, growing evidence indicates an underlying allergic mechanism for some ICM reactions. Accordingly, there have been trials to evaluate the clinical value of skin testing using ICM. However, few studies have yet investigated the role of intradermal skin tests (IDT) when selecting alternative contrast media in the patients with history of hypersensitivity reaction to ICM.
In a recently published article in The Journal of Allergy and Clinical Immunology: In Practice, Kwon et al. evaluated IDT as a tool for preventing recurrent hypersensitivity reactions to ICM. The study subjects had experienced hypersensitivity reactions to ICM and were referred to the allergy clinic in Asan Medical Center from April 2015 to April 2018. All patients underwent IDT with 7 different ICMs, including the causative ICM. Medical records were retrospectively analyzed, and the data were compared according to the IDT results using the culprit ICM.
Except for 4 patients with unknown culprit ICM, a total of 69 patients were included in the study. Thirty-eight patients showed positive IDT results to the culprit ICM (CULPRIT+) while 31 patients showed negative results (CULPRIT-). Sixteen patients from the CULPRIT+ group, and 22 from the CULPRIT- group were subsequently exposed to an ICM. In the CULPRIT+ group, 4 of the 5 patients who were subsequently exposed to an IDT-positive ICM re-experienced hypersensitivity reactions. When patients were exposed to IDT-negative ICM as an alternative, hypersensitivity reactions were not observed. In the CULPRIT- group, IDT-positive ICMs did not provoke hypersensitivity reactions while 2 patients using IDT-negative ICMs experienced hypersensitivity reactions. In short, when the culprit ICM produced an IDT-positive result, IDT-negative ICM could be used as a safer alternative. However, when the culprit ICM was IDT-negative, further skin tests were not helpful, and premedication plus changing to another ICM was enough to prevent hypersensitivity reactions. These results suggest a practical role of skin testing for preventing recurrent hypersensitivity reactions in previous reactors, even though future prospective studies are warranted for validation.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.