title: Premedication of patients for prior urticarial reaction to iodinated contrast medium.
abstract: OBJECTIVE
  The purpose of this study was to determine whether premedication of patients with a history of urticaria after low osmolality contrast media (LOCM) results in fewer subsequent reactions, and if a benefit is seen, to determine which premedication regimen results in the fewest reactions.
  
  
  METHODS
  The subsequent contrast enhanced studies of patients who experienced urticaria after intravenous LOCM between 2002 and 2009 were reviewed to determine whether an additional reaction occurred. Patients undergoing subsequent studies received either no premedication, or premedication with diphenhydramine alone, corticosteroid alone, or corticosteroid plus diphenhydramine. Reactions occurring without premedication were termed repeat reactions and reactions occurring after premedication were termed breakthrough reactions.
  
  
  RESULTS
  Fifty patients with a history of urticaria after LOCM met the inclusion criteria and underwent 133 subsequent contrast enhanced studies. Repeat reactions occurred in 7.6% (5/66) of subsequent studies in patients receiving no premedication. Breakthrough reactions occurred in 8% (2/25), 46% (12/26), and 44% (7/16) of subsequent studies in patients receiving premedication with diphenhydramine, corticosteroid, and corticosteroid plus diphenhydramine, respectively. All subsequent reactions consisted of urticaria as the most severe manifestation; no hemodynamic instability or respiratory compromise occurred. In multivariate analysis, premedication with corticosteroid was significantly associated with higher rate of breakthrough reaction relative to no premedication (OR 14.3, 95% CI: 4.1-50.4), as was premedication with corticosteroid plus diphenhydramine (OR 8.3, 95% CI: 1.8-37.9).
  
  
  CONCLUSIONS
  The results suggest that premedication of patients with a history of urticaria after LOCM may not be necessary.
authors.affiliation: Department of Radiology, Mayo Clinic, 200 1st Street SW, Rochester, MN, 55905, USA, kolbe.amy@mayo.edu.
authors.forename: Amy B
authors.initials: AB
authors.lastname: Kolbe
authors.forename: Robert P
authors.initials: RP
authors.lastname: Hartman
authors.forename: Tanya L
authors.initials: TL
authors.lastname: Hoskin
authors.forename: Rickey E
authors.initials: RE
authors.lastname: Carter
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Maddox
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Hunt
authors.forename: Gina K
authors.initials: GK
authors.lastname: Hesley
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage / Q000009:adverse effects*; D004155:Diphenhydramine / Q000627:therapeutic use*; D003875:Drug Eruptions / Q000209:etiology* / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007455:Iodine / Q000008:administration & dosage / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D011292:Premedication; D012189:Retrospective Studies; D012720:Severity of Illness Index
chemical_list: D000305:Adrenal Cortex Hormones; D003287:Contrast Media; D004155:Diphenhydramine; D007455:Iodine