Empiric Switching of Gadolinium-Based Contrast Agents in Patients With History of Previous Immediate Hypersensitivity Reaction to GBCA: A Prospective Single-Center, Single-Arm Efficacy Trial

CAR/CSACI Practice Guidance for Contrast Media Hypersensitivity

Contrast media, including iodinated contrast media and gadolinium-based contrast agents, are commonly administered pharmaceuticals with excellent safety profiles. However, a minority of the population may experience a hypersensitivity reaction following intravenous administration. Hypersensitivity reactions can be immediate or delayed, and range from mild, such as urticaria, to severe, including anaphylaxis. There is emerging evidence that longstanding pretreatment protocols, such as diphenhydramine and corticosteroids, are ineffective and have the potential for side effects and other harms. Moreover, the evidence for efficacy on which this practice is based is weak and outdated. A joint collaborative working group of representatives from the Canadian Association of Radiologists and the Canadian Society of Allergy and Clinical Immunology was assembled to inform medical professionals and hospital policies regarding hypersensitivity reactions to contrast media. The objectives of the working group were to provide an overview of the epidemiology, physiology, risk factors, and types of hypersensitivity reactions; to synthesize the evidence for pretreatment strategies that minimize the risk of a breakthrough reaction for both iodinated contrast media and gadolinium-based contrast agents; to review the allergy investigations used to evaluate patients with a history of severe hypersensitivity reaction; and to provide an overview of existing guidelines. Following appraisal of the evidence, the working group established recommendations based on consensus in this practice guidance.

Hypersensitivity reactions after diagnostic nonvascular administration of iodine-based contrast media and gadolinium-based contrast agents and the role of the drug allergy specialist

The risk of hypersensitivity reactions (HSR) following nonvascular administration of contrast media (CM) for diagnostic studies is very low, likely due to minimal absorption into the systemic circulation. Most published individual cases of HSR after nonvascular CM administration are immediate reactions caused by ionic high-osmolar CM, few by nonionic low-osmolar CM, and none by gadolinium-based contrast agents. Measures to prevent recurrent HSR following nonvascular administration are similar to those recommended to prevent HSR after intravascular CM administration. Premedication as preventive measure has been abandoned, while switching to an alternative CM, preferably based on the results of an allergological analysis, is increasingly advocated. In selected scenarios, preventive measures may be minimized.

Iodine and Gadolinium Contrast Reactions: What Is the Risk and Role of Premedication, Abbreviated Protocols, Prior History of Reactions, and Cross-Reactivity?

Immediate hypersensitivity reactions to iodinated contrast media and gadolinium-based contrast media can be life-threatening. While corticosteroid premedication or agent-switching may mitigate risk, evidence is largely indirect and based on historical studies; recent literature refutes the efficacy. Guidance on premedication varies between organizations worldwide. No strategy eliminates reactions, and indirect consequences of premedication are substantial. Accelerated regimens are often used for emergencies, but are of questionable efficacy. Identifying "high-risk" patients is complex, but a history of reactions (to the same contrast class) is the biggest risk factor.

Relationship Between Patient-Friendly Audiovisual Systems and MRI Contrast Agent to Adverse Reactions

BACKGROUND

Patient-friendly audiovisual (AV) systems in head MRI examinations can potentially reduce patient anxiety and contrast-enhanced MRI (CE-MRI) adverse reactions to gadolinium.

PURPOSE

To evaluate whether a patient-friendly AV system reduces the rate of adverse reactions to gadolinium-based contrast agents.

STUDY TYPE

Retrospective.

POPULATION

Four thousand eight hundred thirty-two outpatients (2462 female) attending for clinical CE-MRI studies. (Gadoteridol: 1971, Meglumine gadoterate: 2733, Gadobutrol: 128.) FIELD STRENGTH/SEQUENCE: Routine CE-MRI of head and neck using a 1.5 T or 3 T scanner with or without a patient-friendly AV system.

ASSESSMENT

One thousand one hundred fifty-nine patients were scanned on MRI machines equipped with patient-friendly AV systems (AV group) and 3673 on MRI machines without AV systems (control group). Adverse reaction rate and symptoms were reviewed by referring to the system database and electronic medical records and compared between the two groups. Adverse reactions were defined as physiological reactions, such as vomiting and allergic-like reactions, such as urticaria, occurring within 1 hour of contrast injection. We compare patient backgrounds, adverse reaction rate, adverse reactions symptoms and the severity between the two groups.

STATISTICAL TESTS

Adverse reaction rate with and without a patient-friendly AV system were compared using Fisher's exact test. The relationship between patient-friendly AV systems and the occurrence of adverse reactions was evaluated with logistic regression. Statistical significance was set at P < 0.05.

RESULTS

Of the 4832 patients enrolled, 65 (1.35%) experienced adverse reactions. The most common adverse reactions in both groups were urticaria and pruritus. Adverse reaction rate was significantly lower in the AV group than in the control group (0.7% vs. 1.6%). No significant difference was observed in the severity (P = 1.000) of adverse reactions and symptoms (allergic-like reaction: P = 0.08, physiologic reaction: P = 1.000) between the two groups.

DATA CONCLUSION

The patient-friendly AV system significantly reduce adverse reaction occurrence to gadolinium-based contrast agents.

EVIDENCE LEVEL

4 TECHNICAL EFFICACY: Stage 1.

Severity of Flare Reactions in Diethylenetriamine Pentaacetate Chelations: Report on Different Immune Dampening Strategies in Clinical Practice

PURPOSE

The aim of this study was to report early clinical experience with various forms of immune dampening to mitigate the expected flare reaction in patients suffering from gadolinium deposition disease (GDD) receiving DTPA chelation.

MATERIALS AND METHODS

All patients were clinical subjects, and no prospective research was performed on them. The study included 31 consecutive patients (21 women; age, 46.2 ± 12.5 years). The diagnosis of GDD was clinically made. The severity of the flare over the week after each chelation session was rated on a scale from 1 to 10 (where 1 is negligible, 10 is intolerably severe). Patients were followed for up to 5 chelation sessions. Four immune dampening strategies were used: (1) no concurrent treatment; (2) antihistamine plus montelukast (AH); (3) steroid/antihistamine taper postchelation (SAHT); and (4) steroid/antihistamine extending from prechelation to 5 days postchelation (extended hypersensitivity medication regimen; EHMR). The data were analyzed with generalized linear mixed models and with linear regression.

RESULTS

A total of 102 flare scores were obtained at different time points. Ten patients underwent 5 chelations. The severity of the flare after the first chelation was significantly higher in cases of no concurrent therapy (8.4 ± 2.6) and AH (7 ± 1.4) compared with SAHT (6 ± 1.3) and EHMR (5 ± 1.1). Patients who underwent SAHT and EHMR experienced less severity of flare after the first chelation (P = 0.0049 and P = 0.0005, respectively). Considering all time points, the results were also significantly better with SAHT and EHMR.

CONCLUSION

Based on early clinical experience, EHMR seems to manage flare reactions in DTPA chelation well. This strategy may represent the first standard therapy in patients with GDD.

Prevention of Drug Hypersensitivity Reactions: Prescreening and Premedication

Drug hypersensitivity reactions (DHR) are heterogeneous in their pathomechanisms, clinical presentation, severity, and outcomes. Novel DHR mechanisms, phenotypes, and endotypes have been described. The key to prevention from further exposure to the culprit drugs involves correct identification of the putative drug through a combination of in vitro and/or in vivo tests, accurate drug allergy labeling and reporting, and electronic decision support systems within electronic medical records to prevent future accidental prescribing. Prescreening and premedication, the focus of this review, may be a useful adjunct to preventive measures in certain situations. After an index immediate drug hypersensitivity reaction, prescreening may be useful in perioperative anaphylaxis, and iodinated (ICM) and gadolinium-based contrast media (GCM) where the culprit and potential alternative agents are skin tested. In certain nonimmediate DHR, pharmacogenomic prescreening may be used before prescribing high-risk drugs (eg, carbamazepine and allopurinol) where specific human-leukocyte antigen genotypes are associated with severe cutaneous adverse reactions. Premedication with antihistamine and systemic corticosteroids is another therapeutic strategy to prevent infusion reactions for certain biologicals and chemotherapeutic agents, in cases of perioperative anaphylaxis, ICM and GCM DHR, and clonal mast cell disorders. Rapid drug desensitization may also be used to induce temporary tolerance in situations where there are limited alternative drugs.