Adverse Reactions to CT Contrast Agents: A 10-Year Study of Clinical and Environmental Risk Factors

<b>Background</b>: Iodinated contrast agents are widely used in computed tomography (CT) imaging; however, they can cause adverse drug reactions (ADRs) ranging from mild hypersensitivity to severe anaphylaxis. While several clinical risk factors have been identified, large-scale studies incorporating environmental variables remain limited. This study aimed to assess the prevalence and predictors of contrast agent-related ADRs over a 10-year period. <b>Methods</b>: We retrospectively analyzed 221,962 adult outpatients who underwent contrast-enhanced CT between January 2014 and December 2023 at a single tertiary center: Patient characteristics, clinical conditions (e.g., hypertension, allergy history), contrast agent types, premedication status, seasonal trends, temperature, and humidity were examined. ADRs were categorized as mild, moderate, or severe based on American College of Radiology (ACR) guidelines. Logistic regression was used to identify independent predictors. <b>Results</b>: The overall prevalence of ADRs was 0.64% (1423 cases). ADRs were more frequent in females, younger patients, and those receiving premedication. Seasonal and environmental patterns were evident: higher ADR rates occurred in summer and autumn, with positive correlations to ambient temperature and humidity. Among contrast agents, Ioversol (1.4%) and Iomeprol (1.2%) showed the highest ADR rates. The prevalence of mild ADRs increased in the post-COVID-19 period, while that of moderate reactions declined. <b>Conclusions</b>: This real-world study identified multiple clinical and environmental factors associated with ADRs to iodinated contrast agents in CT imaging. The findings suggest the importance of individualized risk assessment and the consideration of environmental factors when planning contrast administration.