Assessment of an Allergy Study Including Rapid Provocation Tests to Identify a Safe Alternative Contrast Agent and Phenotyping of Patients With a History of Hypersensitivity to Iodinated Contrast Media.

Abstract

Background and objective: Provocation tests with contrast media are increasingly necessary to complete an allergy work-up. However, they are not standardized. Objective: We aimed to evaluate a rapid provocation test in patients with a history of anaphylaxis. Our secondary objectives included phenotyping the study population and proposing a predictive methodology for allergy test outcomes.

Methods: We performed an allergy study using iohexol, iodixanol, ioversol, and iobitridol in patients ≥18 years of age with previous hypersensitivity reactions to iodinated contrast media. A rapid provocation test (100 cc administered in 12 minutes) was performed using a noninvolved iodinated contrast medium that had yielded negative skin test results. The statistical analysis comprised binary logistic regression and cluster analysis.

Results: A total of 130 patients were enrolled. Ninety-six patients (74%) developed cutaneous symptoms exclusively, while 17 patients (13%) experienced anaphylaxis. Nine patients (7%) had positive skin test results, and 20 of 141 provocation tests performed were positive. All patients developed mild cutaneous symptoms, including those with a history of anaphylaxis. A safe alternative contrast medium was recommended to 122 patients (94%), with good tolerance in 50 patients in a new radiological examination. We identified 3 patient phenotypes, each associated with a different risk of a positive drug provocation test result. A predictive model for allergy test outcomes was developed, although its statistical predictive capacity was low.

Conclusions: We confirmed the efficacy and safety of a protocol including rapid provocation tests in patients with hypersensitivity reactions to iodinated contrast media of varying severity. Three patient clusters were identified, each showing a different risk level for a positive provocation test result.