title: Delayed adverse reaction to contrast-enhanced CT: a prospective single-center study comparison to control group without enhancement.
abstract: OBJECTIVE
  To prospectively assess the incidence of delayed adverse reactions (DARs) in patients undergoing contrast material-enhanced computed tomography (CT) with the low osmolar nonionic contrast agent iohexol and compare with the incidence of DARs in patients undergoing unenhanced CT as control subjects.
  
  
  METHODS
  Institutional review board approval and informed written consent for this prospective study were obtained. The study was HIPAA compliant. Patients undergoing CT for routine indications were enrolled from a random next-available scheduling template by an on-site clinical trials monitor. All subjects received a questionnaire asking them to indicate any DAR occurring later than 1 hour after their examination. Sixteen manifestations were listed and included rash, skin redness, skin swelling, nausea, vomiting, and dizziness, among others. To ensure maximal surveillance, a clinical trials coordinator initiated direct telephone contact for further assessment. Patients suspected of having moderately severe cutaneous reactions were invited to return for a complete dermatologic clinical assessment including skin biopsy, if indicated. Statistical analysis was performed by using a two-sided Wilcoxon-Mann-Whitney test, a logistic regression utilizing a chi(2) test to adjust for sex and age, and a two-sided Fisher exact test.
  
  
  RESULTS
  A total of 539 patients (258 receiving iohexol and 281 not receiving contrast material) were enrolled. DARs were observed in 37 (14.3%) of 258 subjects receiving iohexol and in seven (2.5%) of 281 subjects in the control group (P < .0001, chi(2) test) after adjusting for sex and age. Specific manifestations of DARs that were significantly more frequent at contrast-enhanced CT were skin rash (P = .0311), skin redness (P = .0055), skin swelling (P = .0117), and headache (P = .0246). DARs involving the skin included generalized rashes of the face, neck, chest, back, and extremities and were often associated with swelling, erythema, and pruritus.
  
  
  CONCLUSIONS
  This study substantiates a frequent occurrence of DARs at contrast-enhanced CT compared with that in control subjects. Continued growth in the use of contrast-enhanced CT suggests a need for greater awareness and attention to prevention and management.
authors.affiliation: Department of Diagnostic Radiology, University of California, Davis Medical Center, 4860 Y St, Suite 3100, Sacramento, CA 95817, USA. shaun.loh@ucdmc.ucdavis.edu
authors.forename: Shaun
authors.initials: S
authors.lastname: Loh
authors.forename: Sepideh
authors.initials: S
authors.lastname: Bagheri
authors.forename: Richard W
authors.initials: RW
authors.lastname: Katzberg
authors.forename: Maxwell A
authors.initials: MA
authors.lastname: Fung
authors.forename: Chin-Shang
authors.initials: CS
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003287:Contrast Media / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000139:chemically induced* / Q000453:epidemiology; D015994:Incidence; D007472:Iohexol / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D007472:Iohexol
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