Radiology: Volume 253: Number 2–November 2009
Matthew S. Davenport, MD Richard H. Cohan, MD Elaine M. Caoili, MD James H. Ellis, MD
PURPOSE: To determine the frequency, type, and severity of break_through and repeat breakthrough reactions to iodinated low-osmolality contrast medium (LOCM) in patients who were premedicated with corticosteroids and antihista_mines.
OBJECTIVE. Institutional review board approval was obtained, and in_formed consent was waived for this retrospective HIPAA-compliant analysis. One hundred ninety breakthrough al_lergic-like reactions to intravenous LOCM in 175 patients with a history of contrast medium reactions were re_viewed. The repeat breakthrough reactions that resulted from 197 additional LOCM-enhanced examinations per_formed in 58 patients after the initial breakthrough reac_tion 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 reac_tion. Subgroup analysis was performed to determine if the contrast medium type, contrast medium volume, and/or time between the initial (index) and breakthrough reac_tions affected the breakthrough reaction severity.
MATERIALS AND METHODS. Institutional review board approval was obtained, and in_formed consent was waived for this retrospective HIPAA-compliant analysis. One hundred ninety breakthrough al_lergic-like reactions to intravenous LOCM in 175 patients with a history of contrast medium reactions were re_viewed. The repeat breakthrough reactions that resulted from 197 additional LOCM-enhanced examinations per_formed in 58 patients after the initial breakthrough reac_tion 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 reac_tion. Subgroup analysis was performed to determine if the contrast medium type, contrast medium volume, and/or time between the initial (index) and breakthrough reac_tions 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 break_through reactions in the patients with a mild index reac_tion 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 break_through reaction. Breakthrough reactions were signifi_cantly 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 injec_tions usually do not induce repeat breakthrough reactions. Breakthrough reactions are more likely to be moderate or severe in patients with certain risk factors.