100138 - Diagnostic Value of Mixed Iodinated Contrast Media Skin Testing in Patients with Radiocontrast Media Hypersensitivity

Skin testing is recommended for the evaluation of radiocontrast media (RCM) hypersensitivity; however, the diagnostic and clinical utility of mixed iodine contrast media skin testing has not been well established. We aimed to assess the efficacy of mixed RCM intradermal testing compared with individual RCM testing and to evaluate clinical factors associated with pharmacologic prevention outcomes.

We retrospectively analyzed 157 patients (mean age 57.8 ± 13.9 years; 40.9% male) with a history of RCM hypersensitivity who underwent intradermal skin testing. Patients were classified into three groups according to skin test results: (1) individual contrast positive only (n=47), (2) mixed + individual contrast positive (n=25), and (3) mixed positive + individual contrast negative (n=85). Demographic characteristics, culprit RCM, clinical manifestations, and recurrence of adverse drug reactions (ADR) after premedication were compared. Logistic regression analysis was performed to identify factors affecting pharmacologic prevention outcomes in delayed hypersensitivity reactions.

At least one positive intradermal test was observed in 45.9% of patients. The most common culprit agents were iohexol (42.7%) and iopamidol (38.9%). Cutaneous symptoms were predominant (66.9%), followed by respiratory (27.4%) and gastrointestinal involvement (19.1%). Clinical characteristics did not significantly differ among groups according to skin test patterns. In multivariate logistic regression analysis adjusted for age and sex, greater reaction severity (calculated as the product of symptom duration and organ involvement score) was independently associated with poorer preventive outcomes (OR 0.029, 95% CI 0.004–0.227, P=0.001). Age and sex were not significant predictors.

Mixed RCM intradermal testing identified additional sensitized patients beyond individual contrast testing alone. Although clinical phenotypes were comparable across groups, reaction severity was the key determinant of pharmacologic prevention failure. Mixed iodine contrast media skin testing may provide complementary diagnostic value in patients with RCM hypersensitivity