Clinical value of radiocontrast media skin tests as a prescreening and diagnostic tool in hypersensitivity reactions

Background: Some radiocontrast media (RCM) hypersensitivity reactions may have underlying IgE- or T-cell-mediated mechanisms. RCM skin testing may be useful for predicting future reactions. Objective: To investigate the clinical value of RCM skin testing before computed tomography and after RCM hypersensitivity reactions. Methods: Patients who underwent RCM skin testing were a prospective sample of convenience at a single medical center and were tested just before their pending nonionic RCM-enhanced computed tomogram. In addition, skin test data of patients who were referred to the allergy clinic because of their previous RCM hypersensitivity reactions were reviewed retrospectively. Results: A total of 1048 patients enrolled in the study prospectively. Of these, 672 (64.1%) had never been exposed to RCM. Of the 376 previously exposed to RCM, 61 (16.2%) had a history of at least one mild RCM-associated reaction, 56 (91.8%) had immediate reactions, and 5 had no-immediate reactions. There was only 1 positive immediate hypersensitivity RCM skin test result (0.09%). There were 51 mild immediate reactions (4.9%), 1 moderate immediate reaction (0.09%), 8 mild nonimmediate reactions (0.76%), and 1 moderate nonimmediate reaction (0.09%). There was only 1 positive delayed hypersensitivity skin test result (0.09%), retrospectively determined, in 1 (11.1%) of the nonimmediate RCM-associated reactions. Sensitivity of RCM skin testing was significantly higher with severe immediate reactions (57.1%) than mild reactions (12.9%) and moderate reactions (25.0%) in the retrospective review of diagnostic skin test data (P =.03). Conclusion: RCM skin testing for screening is of no clinical utility in predicting hypersensitivity reactions. RCM skin testing may have modest utility in retrospectively evaluating severe adverse reactions.