What is the clinical value of negative predictive values of skin tests to iodinated contrast media?

ABSTRACT

BACKGROUND: Iodinated contrast media (ICM) can cause hypersensitivity reactions (HSR), yet data are scant about the negative predictive value (NPV) of ICM skin tests. OBJECTIVE: To determine the NPV of skin tests to ICM Methods: We enrolled 73 patients with a history of HSRs to ICM, 136 subjects with no previous exposure to ICM, and, as controls, 47 subjects who had previously tolerated ICM. All the subjects had skin tests with the culprit and/or alternative ICM and were later questioned as to whether they were reexposed and/or reacted to the skin-test-negative ICM. RESULTS: Sixty (82.2%) and 13 (17.8%) patients had a history of immediate HSR and those with a history of nonimmediate HSR, respectively. The sensitivity and specificity of the skin tests were 18% and 97%, respectively, in patients with immediate HSR and were 23% and 99%, respectively, in patients with nonimmediate HSR. Of a total of 237 subjects with negative skin test results, 207 (87.3%) were asked about further ICM administration; 158 (84.9%) confirmed subsequent use either with (n = 15 [9.4%]) or without premedication (n = 143 [90.6%]). Of the 143 individuals, 140 tolerated skin-test-negative ICMs but three (1.9%) reacted to ICMs (two with mild nonimmediate reactions, one with a grade 1 immediate reaction). Of 20 patients who had previous HSR to ICM, 17 tolerated further skin-test-negative ICM without premedication. The NPV of ICM skin tests, therefore, was 97% (95% confidence interval, 7599%). CONCLUSION: The NPV of skin tests with ICM was high. None of the reactions in patients who had negative skin test results were severe, which may reassure physicians who hesitate to perform further evaluations in patients with negative skin test results.