Repeat Contrast Medium Reactions in Premedicated Patients: Frequency and Severity

Purpose: To determine the frequency, type, and severity of breakthrough and repeat breakthrough reactions to iodinated low-osmolality contrast medium (LOCM) in patients who were premedicated with corticosteroids and antihistamines. Materials and Methods: Institutional review board approval was obtained, and informed consent was waived for this retrospective HIPAA-compliant analysis. One hundred ninety breakthrough allergic-like reactions to intravenous LOCM in 175 patients with a history of contrast medium reactions were reviewed. The repeat breakthrough reactions that resulted from 197 additional LOCM-enhanced examinations performed in 58 patients after the initial breakthrough reaction were also reviewed. The Fisher exact test was used to determine if certain risk factors were associated with an increased risk of a moderate or severe breakthrough reaction. Subgroup analysis was performed to determine if the contrast medium type, contrast medium volume, and/or time between the initial (index) and breakthrough reactions affected the breakthrough reaction severity. Results: Of 128 breakthrough reactions in which the index reaction severity was known, 103 (81%) were of a severity similar to that of the index reaction, 15 (12%) were less severe, and 10 (8%) were more severe. The severity of the breakthrough reactions in the patients with a mild index reaction was usually (in 94 [91%] of 103 reactions) mild. When the index reaction was severe, the breakthrough reaction was usually moderate or severe (in eight [42%] of 19 cases and four [67%] of six cases, respectively). The majority (174 [88%] of 197) of LOCM injections after the initial breakthrough reaction did not result in a repeat breakthrough reaction. Breakthrough reactions were significantly more likely to be moderate or severe in patients with a history of chronic oral corticosteroid use (P = .01), drug (P = .04) or severe (P < .001) allergies, or allergies to four or more allergens (P = .01). Conclusion: Breakthrough reactions are usually similar in severity to the index reaction, and subsequent contrast medium injections usually do not induce repeat breakthrough reactions. Breakthrough reactions are more likely to be moderate or severe in patients with certain risk factors. (C) RSNA, 2009