title: Frequency of late allergy-like adverse reactions following injection of intravascular non-ionic contrast media. A retrospective study comparing a non-ionic monomeric contrast medium with a non-ionic dimeric contrast medium.
abstract: OBJECTIVE
  A retrospective study was undertaken of the late adverse reactions following the injection of contrast media. The purpose was to determine whether there was a difference between non-ionic monomeric (iohexol) and non-ionic dimeric (iodixanol) contrast media in the reactions produced.
  
  
  METHODS
  A total of 3,408 patients were sent a written questionnaire in which they were asked to confirm or deny any subjective discomfort or adverse event during a period of one hour to one week after a previous radiological examination with contrast medium. Patients who had undergone angiography (i.v. or i.a. injection) and CT (i.v. injection) were included. Objective signs of an allergy-like reaction were listed and the patients were asked to subjectively quantify any consequent discomfort.
  
  
  RESULTS
  The compliance rate was 84%. Of the 3075 injections finally included in the study, 133 (4.3%) had resulted in contrast-medium-related adverse reactions of which 72 (2.3%) were immediate and 61 (2%) were late. Iohexol induced late reactions in 14/851 (1.7%) cases, and iodixanol in 24/1218 (2.0%) cases following i.v. injection and in 23/1006 (2.3%) cases following i.a. injection. The differences were not significant. There were no differences between the two contrast media in the subjective rating of discomfort except that the patients who had received iodixanol also had the highest individual-intensity score. No patient had been hospitalized owing to an adverse reaction and all reactions had been regarded as mild or moderate.
  
  
  CONCLUSIONS
  The number of late adverse reactions was low. There was no difference in the frequency of the late adverse reactions following i.v. injection between iodixanol and iohexol. There was also no difference in the reactions between the i.a. and i.v. injections of iodixanol.
authors.affiliation: Department of Diagnostic Radiology, Karolinska Institute, Huddinge University Hospital, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Rydberg
authors.forename: J
authors.initials: J
authors.lastname: Charles
authors.forename: P
authors.initials: P
authors.lastname: Aspelin
mesh_terms: D003287:Contrast Media / Q000009:adverse effects*; D004417:Dyspnea / Q000139:chemically induced / Q000453:epidemiology; D006801:Humans; D007269:Injections, Intra-Arterial; D007275:Injections, Intravenous; D007472:Iohexol / Q000009:adverse effects*; D011537:Pruritus / Q000139:chemically induced / Q000453:epidemiology; D012189:Retrospective Studies; D012872:Skin Diseases, Vesiculobullous / Q000139:chemically induced / Q000453:epidemiology; D014283:Triiodobenzoic Acids / Q000009:adverse effects*; D014581:Urticaria / Q000139:chemically induced / Q000453:epidemiology
chemical_list: D003287:Contrast Media; D014283:Triiodobenzoic Acids; D007472:Iohexol; C044834:iodixanol