Validation of the Prescreening Intradermal Skin Test for Predicting Hypersensitivity to Iodinated Contrast Media: A Prospective Study with ICM Challenge

Background: The number of hypersensitivity reactions associated with iodinated contrast media (ICM) is increasing with widespread use of radiographic contrast agents. These hypersensitivity reactions are unpredictable and sometimes lead to severe reactions such as anaphylaxis. Objective: To investigate the value of intradermal skin test (IDT) as a clinical screening tool for prediction of a hypersensitivity reaction to ICM. Methods: We performed IDT in the patients scheduled to receive an iodinated contrast agent between September 2015 and April 2017. After IDT, the contrast agent tested was administered intravenously, regardless of the results of skin testing, and the patients were carefully monitored. Results: We recruited 2,918 patients in 2 hospitals, and 2,843 were included in the final analysis. Fifteen (0.5%) of the 2843 patients had a positive IDT result before scheduled computed tomography scan; however, none of these patients experienced a hypersensitivity reaction after the administration of a full dose of ICM. Meanwhile, 19 patients who experienced hypersensitivity reactions after ICM challenge had showed a negative IDT result. The sensitivity and the positive predictive value of IDT for ICM were both 0%. Conclusions: Routine IDT before the administration of an iodinated contrast agent does not predict hypersensitivity considering its extremely low sensitivity and a low positive predictive value.