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.