Patients have very limited knowledge of their contrast allergies


      • Very few people with a prior allergic reaction to an iodinated-contrast agent know which agent they are allergic to.
      • Over half of people with a contrast allergy could not name where the reaction occurred, limiting old record acquisition.
      • Most people with a contrast allergy do not remember when the reaction occurred, limiting knowledge if the agent was older ionic, no longer commonly used.
      • Better documentation, education of patients and providers may improve knowledge of patients’ specific contrast allergies, helping tailor future studies.



      To quantify patients' knowledge of their iodinated contrast allergies; and to compare this data to literature estimates of patient knowledge of other medication allergies.


      Using a key word search of 15,715 patients undergoing a total of 19,043 CT studies over a six-month period, a cohort of 307 adult patients claiming prior allergic reaction to iodinated intravenous contrast was identified. A patient questionnaire with the CT studies inquired about the specifics of their contrast allergy, including the symptoms of their prior allergic reaction; when and where the reaction occurred; and if patients could name the contrast agent to which they claim to be allergic.


      In the cohort of 307 patients claiming a prior allergic reaction to iodinated contrast, 86.6% could describe their prior allergic reaction symptoms. Only 36.8% could provide an approximate year of the reaction, with an additional 6.5% claiming that their reactions were remote, for a total of 43.3% providing some information when their reaction occurred. 56.7% provided no information on the year of their reaction. 40.7% named either the facility or the city where the reaction occurred, while 59.3% could not. Only 5 of 307 (1.6%, p < 0.00001) could name the contrast agent to which they believed they were allergic.


      Other studies have reported inconsistencies, limited documentation, and limited ability to confirm patients' pharmacologic allergies, estimating that patients prior to pharmacist consultation are approximately 60-70% accurate in listing their drug allergies by name. Nevertheless, patients' knowledge of their iodinated contrast allergies is markedly more limited when compared to expected patient knowledge of medication allergies in general.


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