Persistence of Sensitization to Contrast Media (PersensPC)

Evolution of IgE-mediated Sensitization to Contrast Media in Allergic Patients Diagnosed by Positive Skin Tests

The study aims to evaluate the persistence of IgE-mediated allergy to contrast media (CM) after a second exposure in patients who tested positive at both the first and second evaluations for CM allergy. It also aims to analyze the risk factors associated with the persistence of IgE-mediated sensitization after the second allergological assessment.

Study Overview

• Status: Not yet recruiting
• Conditions: Contrast Media Allergy
• Intervention / Treatment: Diagnostic test: Skin testing; Other: Baseline serum tryptase measurement

Detailed Description

Drug allergy is often overdiagnosed, as only about 25% of cases labeled as allergic are confirmed. IgE-mediated drug allergy, responsible for immediate reactions up to anaphylaxis, carries inherent risks and relies primarily on in vivo testing, supplemented by in vitro assays in selected cases. In vivo assessment includes skin tests (ST), which, when positive, detect drug-specific IgE bound to mast cells, and drug provocation tests (DPT), which involve controlled re-exposure to the suspected drug.

When IgE-mediated allergy is confirmed, drugs with positive ST are strictly contraindicated for life. Drugs with negative ST are generally considered safe, and tolerance is often verified through DPT performed in specialized settings using stepwise dose escalation up to near-therapeutic doses. In some cases, drugs are reintroduced directly in real-life conditions without prior DPT.

Contrast media (CM) can trigger systemic reactions even at very low doses. In such cases, in vitro testing should ideally precede DPT to minimize systemic exposure. However, its use is limited by the small number of commercially available drug allergens, the need for specialized expertise for techniques such as the basophil activation test, and variable sensitivity depending on the drug, which remains largely unknown for CM. Skin testing for CM allergy has a very high negative predictive value (>95%), indicating that most patients with negative ST tolerate subsequent CM exposure. As a result, many centers do not systematically perform DPT after negative ST.

Evidence suggests that IgE-mediated drug allergy, including CM allergy, may decline over time, with conversion from positive to negative ST occurring after several years. However, it is unclear whether this reflects a true loss of clinical allergy, as documented re-exposures are rare and mostly anecdotal. Clinical experience shows that allergy may either resolve or persist despite negative follow-up tests.

Finally, the severity of drug-induced allergic reactions may be increased in patients with mast cell activation syndrome or mastocytosis, conditions characterized by elevated mast cell burden or reactivity and often suspected in the presence of elevated baseline serum tryptase levels.

• Study Type: Observational
• Enrollment (Estimated): 100

Contacts and Locations

• Study Contact: Name: Dr CHIRIAC; Phone Number: +33 04 67 33 61 07; Email: a-chiriac@chu-montpellier.fr

Study Locations

• France
  • Montpellier, France
    • CHU Montpellier
    • Contact: CHIRIAC, Dr; Phone Number: +33 4 67 33 6107; Email: a-chiriac@chu-montpellier.fr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Drug Allergy and Hypersensitivity Database of the Allergy Exploration Unit, Montpellier University Hospital (CHU Montpellier).

Description

Inclusion Criteria:

- Adult patients (≥18 years) with confirmed IgE-mediated allergy to contrast media products after a first exposure.

Exclusion Criteria:

• Patients receiving H1 antihistamines for an allergic condition at the time of evaluation.
• Patients with active eczema and/or uncontrolled asthma.
• Pregnant or breastfeeding women, or women who have recently given birth.
• Individuals under legal protection (e.g., guardianship).
• Individuals deprived of liberty or involved in judicial proceedings.
• Individuals without health insurance coverage.
• Absence of clear, written informed consent.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

IgE-dependent allergy to contrast media; Skin testing using the prick method, involving gentle skin pricking at the site of allergen application, or intradermal testing (IDT) with 0.02-0.05 mL of allergenic solution will be performed in patients with a clinical history of hypersensitivity to contrast media. Baseline serum tryptase measured in blood samples will also be used as an indicator of hypersensitivity to contrast media, with values higher than 11 µg/L considered elevated.

Diagnostic test: Skin testing; Commercial contrast media will be used to perform skin prick testing or intradermal testing with 0.02-0.05 mL of allergenic solution. If not previously performed, a standard panel of prick tests with environmental allergens will be used to assess atopic status. Positive (histamine 10 mg/mL) and negative (saline) controls will be included. Skin testing will begin with prick tests, starting at the dilution that was positive during the initial evaluation. If negative, testing will proceed with intradermal injections using increasing concentrations until a positive response is observed. Once a positive result is obtained, skin testing for that contrast medium will be discontinued. A prick test will be considered positive if a wheal ≥3 mm with erythema and pruritus appears after 15 minutes. An intradermal test will be considered positive if a wheal ≥3 mm with erythema and pruritus appears after 20 minutes.; Other: Baseline serum tryptase measurement; Seven milliliters of venous blood will be collected for baseline serum tryptase measurement.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Prevalence of IgE-mediated allergy to contrast media after the first exposure	A skin prick test is considered positive if, after 15 minutes, a wheal measuring at least 3 mm appears, associated with erythema and pruritus. An intradermal test is considered positive if, after 20 minutes, a wheal measuring at least 3 mm appears, associated with erythema and pruritus	Inclusion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Risk factors of patients with IgE-mediated hypersensitivity to contrast media	The presence of risk factors will be determined by analyzing the association between data extracted from the Drug Allergy and Hypersensitivity Database (DAHD) (i.e., sociodemographic characteristics, initial reaction to contrast media, results of the first allergy tests, and the presence of other allergic factors) and the persistence of reactivity to contrast media in patients with serum tryptase levels higher than 11 µg/L.	Inclusion

Collaborators and Investigators

• Sponsor: University Hospital, Montpellier
• Investigators: Principal Investigator: Dr CHIRIAC, University Hospital, Montpellier

Study record dates

Study Major Dates

• Study Start (Estimated): February 1, 2026
• Primary Completion (Estimated): February 1, 2028
• Study Completion (Estimated): February 1, 2028

Study Registration Dates

• First Submitted: January 29, 2026
• First Submitted That Met QC Criteria: February 10, 2026
• First Posted (Actual): February 13, 2026

Study Record Updates

• Last Update Posted (Actual): February 13, 2026
• Last Update Submitted That Met QC Criteria: February 10, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Allergy; Contrast Media; IgE; Skin test
• Additional Relevant MeSH Terms: Immune System Diseases; Hypersensitivity; Investigative Techniques; Clinical Laboratory Techniques; Diagnostic Techniques and Procedures; Diagnosis; Immunologic Techniques; Immunologic Tests; Skin Tests
• Other Study ID Numbers: RECHMPL22_0320

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No