Immediate Hypersensitivity to Contrast Agents: The French 5-year CIRTACI Study

Area of Science:

• Radiology and Imaging
• Allergy and Immunology
• Pharmacology

Background:

• Immediate hypersensitivity (IH) reactions are associated with iodinated (ICM) and gadolinium-based contrast media (GBCM).
• Distinguishing allergic from non-allergic IH reactions is critical for patient management, as true allergy mandates avoidance of the causative agent.
• This study investigated the frequency of allergic IH reactions in patients exposed to ICM or GBCM.

Purpose of the Study:

• To determine the frequency of allergic immediate hypersensitivity (IH) reactions to iodinated contrast media (ICM) and gadolinium-based contrast media (GBCM).
• To compare the characteristics of allergic, potentially allergic, and non-allergic IH reactions.
• To evaluate the utility of skin testing in diagnosing allergic reactions to contrast media.

Main Methods:

• A multicenter study involving 245 patients who experienced IH reactions to ICM or GBCM between 2005 and 2009.
• Clinical symptoms, plasma histamine and tryptase levels, and skin tests (intradermal tests with diluted and pure contrast media) were recorded.
• Allergic IH was diagnosed by positive intradermal tests (IDT) with 1:10 diluted CM, potentially allergic IH by positive IDT with pure CM, and non-allergic IH by negative IDT.

Main Results:

• Allergic IH reactions were identified in 19.6% of ICM reactors and 27.8% of GBCM reactors.
• Skin cross-reactivity was observed in 26.8% of ICM reactors and 50% of GBCM reactors.
• Allergy frequency correlated with clinical severity, mediator release (histamine, tryptase), and cardiovascular signs; non-allergic reactions were generally less severe and had a longer delay.

Conclusions:

• Allergic IH reactions constituted less than 10% of cutaneous reactions but over 50% of life-threatening reactions.
• ICM and GBCM induced comparable IH reactions in frequency and severity, with frequent cross-reactivity, particularly for GBCM.
• Skin testing with pure contrast agent is proposed as a more sensitive diagnostic method than the standard 1:10 dilution criterion.