E2596. Allergic? Really? Contrast Allergies in an EMR
  1. Connor Huddleston; NYU Grossman School of Medicine
  2. James Babb; NYU Grossman School of Medicine
  3. Evan Stein; NYU Grossman School of Medicine
Documentation of allergies to iodine-based contrast media (IBCM) in the electronic medical record (EMR) can be poor, often comprised of ambiguous allergens and incomplete reporting of reaction type and severity. The purpose of this study is to examine the quality of IBCM allergy documentation in the EMR and to analyze the impact on radiologic management.

Materials and Methods:
The EMR was queried for all patients with an allergy to IBCM, other iodinated products, or shellfish who received contrast-enhanced CT imaging between 1/1/2017 and 12/31/2021 (n = 11,514 patients; 24,626 exams). Allergy data included allergens (n=30), reactions (n = 55; categorized as hypersensitive, physiologic, unknown), and corresponding severities (mild, moderate, severe, unknown). Imaging data included exam type, inpatient status, medications administered, and imaging orders canceled within 3 days of the study performed. For each study, use or nonuse of premedication was classified as appropriate, inappropriate or unable to be determined. Appropriate premedication was defined as a patient with a moderate or severe hypersensitivity reaction to IBCM receiving diphenhydramine and a corticosteroid within 24 hours of imaging. Logistic regression for correlated data was used to estimate the percentage of exams that were associated with an appropriate use of premedication and to assess the effect of selected exam- and patient-level factors on the likelihood of appropriate premedication.

Among documented allergic reactions, 11.1% were of unspecified type, and 13.9% lacked severity. Patients were premedicated for 2.9% of imaging studies and the overall percentage of examinations that were preceded by appropriate premedication was 72.6%. Patient age and exam setting were significant independent predictors that an exam would be preceded by appropriate premedication (p<0.01 for both). Appropriate premedication was found to decline linearly as patient age increased, approximately 1.8% for every 10 years of age. Inpatients were significantly more often appropriately premedicated (p=0.01). The presence of an IBCM allergy significantly decreased appropriate premedication (p<0.001), while an allergy to other iodinated products increased appropriate premedication (p<0.001). Rates of appropriate premedication also significantly differed as a function of reported reaction severity, both for hypersensitivity and physiologic reactions (p<0.001). Premedication was noted to significantly increase the delay between imaging order placement and exam completion in inpatients (p=0.036). However, neither imaging delays (p=0.092) nor cancelations (p=0.537) significantly differed as a result of premedication appropriateness.

Age, imaging setting, presence of an IBCM or iodinated product allergy, and allergy severity influenced appropriate premedication use for patients receiving contrast-enhanced CT scans, though premedication appropriateness did not significantly change rates of imaging delays or cancelations. Improved accuracy of the allergy reporting in the EMR would likely lead to improved appropriate premedication.