Evaluation of Hypersensitivity Reactions Associated with Different Non-Iodinated Contrast Media (NICM) at a Tertiary Care Hospital: A Retrospective Cohort Study

Abstract

Background and objective: Non-ionic iodinated contrast media (NICM) are widely used in computed tomography (CT) to enhance imaging of internal structures. Although NICMs reduce hypersensitivity reactions (HSRs) compared with conventional ionic formulations, adverse events including rash, urticaria, and rarely anaphylaxis remain clinically important. This study aimed to evaluate the incidence, clinical characteristics, and severity of HSRs associated with various NICMs.

Methods: A retrospective cohort study included patients undergoing contrast-enhanced CT between January 1, 2021, and December 31, 2023. Immediate HSRs were assessed using the Naranjo algorithm. Descriptive statistics summarized demographics and HSR features, and Fisher’s exact test evaluated differences in severity between contrast agents.

Results: Among 412 patients (42.5% male; median age 60 years, IQR 52–67), most had normal or mildly impaired renal function. Seven NICMs were used. HSRs were predominantly mild-to-moderate cutaneous reactions, mainly rash with itching and urticaria. While anaphylaxis and angioedema were observed in only eight patients. Highest HSR incidences were observed with iomeprol (100.00%), iohexol (88.60%), and iobitridol (88.00%) which severity distribution did not differ significantly among NICMs (p > 0.05). In addition, most reactions were classified as “probable” or “possible” by the Naranjo algorithm.

Conclusion: HSR to NICMs were predominantly mild and largely limited to cutaneous manifestations, while moderate and severe reactions are rare but clinically significant. Although numerical differences in reaction rates were observed among individual contrast agents, no statistically significant association was identified between type of contrast media and severity.