title: Patients with breakthrough reactions to iodinated contrast media have low incidence of positive skin tests.
abstract: BACKGROUND
  The term "breakthrough reactions" designates repeated hypersensitivity reactions to iodinated contrast media (ICM) despite premedication with glucocorticoids and antihistamines. We aimed to retrospectively evaluate the rate of positive skin test (STs) in our cohort of patients with previous breakthrough reactions to different ICMs.
  
  
  METHODS
  A series of 35 patients, who experienced at least one breakthrough reaction to ICM and who underwent STs within 6 months from the reaction were studied, and results were compared to a control group of patients with a first hypersensitivity reaction occurred without premedication. Skin prick tests (SPT), intradermal tests (IDT) and patch tests (PT) at different dilutions, with a set of three to four ICM were performed.
  
  
  RESULTS
  Of the 35 patients with prior breakthrough reactions, 57% had an immediate reaction (IR) and 43% had a non-immediate reaction (NIR). Patients who experienced the first hypersensitivity IR or NIR, later had one or more breakthrough IR or NIR, respectively. Overall, 29% (10/35) of patients with prior breakthrough reactions resulted positive to STs compared to 57% (16/28) of the control group (p < 0.05). No significant difference in allergy history, age, sex, other clinical / demographic features nor chronic use of ACE-inhibitor, beta-blockers or NSAIDs was observed.
  
  
  CONCLUSIONS
  This preliminary finding suggests that patients with prior breakthrough reactions have significantly lower immunologically proven ICM reactions (positive STs) if compared to non-breakthrough patients. According to that, a considerable number of breakthrough reactions seems to be non-allergic hypersensitivity reactions or reactions which could be mostly prevented by a proper, well-timed skin testing. Larger prospective studies are needed to confirm these results, with a more careful analysis of patients' risk factors, a laboratory assessment that includes an in vitro allergy diagnostics, and hopefully a drug provocation test for selected cases.
authors.affiliation: Vita-Salute San Raffaele University, Milan, Italy. Department of Allergy and Clinical Immunology, IRCCS San Raffaele Scientific Institute, Milan, Italy. Phone: +39 02 264 340 78 Fax: +39 02 2634 103 E-mail: berti.alvise@hsr.it.
authors.forename: A
authors.initials: A
authors.lastname: Berti
authors.affiliation: Vita-Salute San Raffaele University, Milan, Italy. Department of Allergy and Clinical Immunology, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Della-Torre
authors.affiliation: Department of Allergy and Clinical Immunology, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Mr
authors.initials: M
authors.lastname: Yacoub
authors.affiliation: Vita-Salute San Raffaele University, Milan, Italy. Department of Allergy and Clinical Immunology, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Tombetti
authors.affiliation: Vita-Salute San Raffaele University, Milan, Italy. Department of Allergy and Clinical Immunology, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Canti
authors.affiliation: Vita-Salute San Raffaele University, Milan, Italy. Department of Allergy and Clinical Immunology, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: M G
authors.initials: MG
authors.lastname: Sabbadini
authors.affiliation: Department of Allergy and Clinical Immunology, IRCCS San Raffaele Scientific Institute, Milan, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Colombo
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media / Q000008:administration & dosage*; D004342:Drug Hypersensitivity / Q000175:diagnosis* / Q000276:immunology / Q000517:prevention & control; D005260:Female; D005938:Glucocorticoids / Q000627:therapeutic use; D006633:Histamine Antagonists / Q000627:therapeutic use; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000139:chemically induced / Q000175:diagnosis* / Q000276:immunology / Q000517:prevention & control; D006969:Hypersensitivity, Immediate / Q000139:chemically induced / Q000175:diagnosis* / Q000276:immunology / Q000517:prevention & control; D007428:Intradermal Tests; D008297:Male; D008875:Middle Aged; D010328:Patch Tests; D011237:Predictive Value of Tests; D012008:Recurrence; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D003287:Contrast Media; D005938:Glucocorticoids; D006633:Histamine Antagonists
keywords: breakthrough reactions; hypersensitivity; intradermal tests; iodinated contrast media; skin tests