Iodinated Contrast Media Hypersensitivity in 115,966 Patients

OBJECTIVES: To assess the prevalence, severity profiles, and risk factors of hypersensitivity reactions (HSRs) to iodinated contrast media (ICM) in a nationwide cohort, and to evaluate the association between iodine concentration and HSR risk, including outcomes in patients receiving premedication, in the context of evolving contrast safety guidelines. MATERIALS AND METHODS: This retrospective cohort study used Korean National Health Insurance Service data from 2016 to 2018. Among 577,115 eligible individuals, 115,966 received ICM. HSRs within 7 days after ICM administration were identified using ICD-10-CM codes and classified as mild, moderate, or severe based on treatment intensity and hospitalization status. Multivariable Cox proportional hazards models and 3:1 propensity score matching were used to identify independent risk factors. Subgroup analyses were performed in 45,885 patients who received corticosteroid and/or antihistamine premedication. Additional analyses stratified by iodine concentration (≤300 vs. >300 mg I/mL; ≤350 vs. >350 mg I/mL) were performed in the full cohort. RESULTS: HSRs occurred in 667 of 115,966 patients (0.58%); 72.4% were mild, 17.1% moderate, and 10.5% severe (severe, 0.06% of all ICM users). Independent risk factors included prior ICM exposure [hazard ratio (HR): 6.168; 95% CI: 4.896, 7.770], prior HSR (HR: 16.675; 95% CI: 3.689, 75.382), asthma (HR: 1.732), allergy (HR: 1.82), and malignancy (HR: 1.804). In the premedication subgroup, prior ICM exposure (HR: 8.362), asthma (HR: 2.03), diabetes mellitus (HR: 1.911), and autoimmune disease (HR: 1.836) were significant predictors. Higher iodine concentrations were associated with modestly higher overall HSR prevalence [eg, 0.64% (>300 mg I/mL) vs. 0.50% (≤300 mg I/mL); P=0.001, and 0.63% (>350 mg I/mL) vs. 0.53% (≤350 mg I/mL); P=0.046], mainly due to increased mild‑to‑moderate reactions, while severe reactions remained stable at 0.06%. CONCLUSIONS: ICM-related HSRs were uncommon and usually mild, and severe reactions were rare in this nationwide cohort. Prior ICM exposure, prior HSR, asthma, allergy, and malignancy were key risk factors for HSRs. Prior ICM exposure, asthma, diabetes mellitus, and autoimmune disease further characterized high-risk patients receiving premedication. Higher iodine concentrations were associated with a modestly higher frequency of mild-to-moderate HSRs, without affecting severe reaction rates. These findings suggest that iodine concentration may represent a potentially modifiable factor in individualized contrast agent selection for high-risk patients.