Skin tests for the exploration of hypersensitivity reactions associated with iodinated contrast media

Clinical outcomes and management of contrast hypersensitivity in patients requiring repeated computed tomography imaging

Introduction: In collaboration with the Department of Rheumatology, Allergy and Immunology, our study aims to review the outcomes of and propose an improved workflow for the management of patients with prior hypersensitivity reactions to iodinated contrast media (ICM). Method: Outpatients coming for contrast-enhanced computed tomography (CECT) were stratified into 3 categories (definite, unconfirmed and inaccurate) based on likelihood of their contrast hypersensitivity label. Patients could be offered a different ICM, receive the same ICM, or be referred to an allergist for further evaluation. There were 4 outcomes: (1) alternative ICM tolerated; (2) same ICM tolerated again; (3) patient developed a hypersensitivity reaction to either alternative or original ICM; and (4) CECT was deferred until assessment by an allergist. Comparison was made pre- and post-intervention to see if patient outcomes were improved. Results: There were 132 patients who made a total of 154 visits (90.3% had documented contrast hypersensitivity). Post-intervention, the number of visits postponed for premedication decreased (81.0% to 34.7%). There was a reduction in hypersensitivity reactions (from 42.9% to 14.3%). Of the 12 patients assessed by the allergist, 6 could continue using the same or alternative ICM, 4 were advised to abstain from further contrast administration and 2 were pending testing with a third agent. Conclusion: Active intervention by the radiologist can decrease the number of postponed, converted or cancelled CECT studies as well as reduce the number of adverse allergic-like events. Direct collaboration between radiologist and allergist for specific cases may be helpful in patients who will likely need future/repeated CECTs. Keywords: Corticosteroid, hypersensitivity, ICM, iodinated contrast media, premedication, skin testing