title: Adverse events after unenhanced and monomeric and dimeric contrast-enhanced CT: a prospective randomized controlled trial.
abstract: OBJECTIVE
  To prospectively evaluate adverse events (AEs) in patients who underwent nonionic monomeric or dimeric contrast media-enhanced computed tomography (CT) and to compare these effects with AEs in patients who underwent unenhanced CT.
  
  
  METHODS
  Local ethics committee approval and written informed consent were obtained. Patients were randomly assigned to the dimeric group, monomeric group, or concurrent control group. Acute (occurring during or within 1 hour after contrast agent injection) and delayed (occurring between 1 hour and 7 days after contrast agent injection) AEs were evaluated and categorized (mild, not requiring treatment; moderate, self-limiting AE requiring simple treatment; severe, AE requiring extensive treatment or endangering life). The two-sided Fisher exact test and the Mann-Whitney U and Wilcoxon signed rank tests were used for statistical analysis.
  
  
  RESULTS
  A total of 895 patients were recruited. Acute AEs were noted significantly (P < .05) more often in the monomeric group (44.8% [133 of 297 patients]) than in the dimeric (23.7% [71 of 300 patients]) or control (9.4% [28 of 298 patients]) groups. Two moderate acute AEs were noted in one patient in each contrast agent group; all other acute AEs were mild. There was no significant difference in the overall incidence of delayed AEs between the dimeric and monomeric groups (53.1% [139 of 262 patients] vs 50.8% [131 of 258 patients]). Delayed cutaneous AEs were noted significantly (P < .05) more often in the dimeric group. A total 16 AEs (2.0%) were moderate; no AE was severe.
  
  
  CONCLUSIONS
  The dimeric contrast agent caused fewer acute AEs than the monomeric contrast agent; however, the dimeric and monomeric agents caused a similar overall number of delayed AEs. Delayed cutaneous symptoms were noted more often with the dimeric contrast agent. Both contrast agents were safe in that no severe AEs and only a few moderate AEs were observed.
authors.affiliation: Department of Radiology, University of Bonn, Hospital and Medical School, Sigmund Freud Str 25, 53105 Bonn, Germany. schild@uni-bonn.de
authors.forename: Hans H
authors.initials: HH
authors.lastname: Schild
authors.forename: Christiane K
authors.initials: CK
authors.lastname: Kuhl
authors.forename: Ute
authors.initials: U
authors.lastname: Hübner-Steiner
authors.forename: Ingrid
authors.initials: I
authors.lastname: Böhm
authors.forename: Ulrich
authors.initials: U
authors.lastname: Speck
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000009:adverse effects* / Q000737:chemistry; D005260:Female; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000139:chemically induced*; D007472:Iohexol / Q000009:adverse effects / Q000031:analogs & derivatives*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016037:Single-Blind Method; D011795:Surveys and Questionnaires; D014057:Tomography, X-Ray Computed / Q000009:adverse effects* / Q000379:methods; D014283:Triiodobenzoic Acids / Q000009:adverse effects*
chemical_list: D003287:Contrast Media; D014283:Triiodobenzoic Acids; C033300:iotrolan; D007472:Iohexol; C038192:iopromide