Iodinated contrast media-induced acute generalized exanthematous pustulosis confirmed by delayed skin tests

Intradermal testing of iodinated contrast media: Should we test up to pure or with diluted compounds only?

BACKGROUND

Intradermal testing (IDT) with iodinated contrast media (ICMs) is an established diagnostic tool in patients with ICM hypersensitivity. Currently, it is unclear which test concentration is the more useful one, up to pure or up to 1:10 diluted ICMs.

METHODS

We searched the literature database PubMed for eligible papers dealing with ICM allergy and their IDT results. We analyzed the data presented by the papers and compared the pooled groups tested with diluted and undiluted ICMs.

RESULTS

We identified 29 eligible original papers, and extracted data of 1137 patients that formed the study population. Although in the cohort tested with diluted ICMs the number of tested ICMs was greater, the percentage of positive tests was significantly less (9.0% vs. 24.7%; P < 0.0001; OR 0.30 [0.26-0.34]). The frequency of positive tested culprit ICMs was also lesser in the group tested with diluted ICMs (31.0% vs. 72.5%; P < 0.0001; OR 0.17 [0.12-0.23]). The number of drug provocation tests (DPTs) was greater in patients with diluted IDTs (374 vs. 89; P < 0.0001; OR 2.54 [1.93-3.36]). We detected an increased sensitivity in patients with undiluted tests (0.774 vs. 0.282) and a nearly identical specificity in both groups (1 vs. 0.983).

CONCLUSIONS

For the first time, we show that IDT up to pure ICM concentrations is superior to using diluted ICMs only. Possibly, we can reduce the number of DPTs when performing IDTs with pure ICMs. In the undiluted group, there were no hints for skin irritations or unspecific test reactions.

Changing patterns in the epidemiology of drug allergy

Drug allergy (DA) remains a complex and unaddressed problem worldwide that often deprives patients of optimal medication choices and places them at risk for life-threatening reactions. Underdiagnosis and overdiagnosis are common and due to the lack of standardized definitions and biomarkers. The true burden of DA is unknown, and recent efforts in data gathering through electronic medical records are starting to provide emerging patterns around the world. Ten percent of the general population engaged in health care claim to have a DA, and the most common label is penicillin allergy. Up to 20% of emergency room visits for anaphylaxis are due to DA and 15%-20% of hospitalized patients report DA. It is estimated that DA will increase based on the availability and use of new and targeted antibiotics, vaccines, chemotherapies, biologicals, and small molecules, which are aimed at improving patient's options and quality of life. Global and regional variations in the prevalence of diseases such as human immunodeficiency virus and mycobacterial diseases, and the drugs used to treat these infections have an impact on DA. The aim of this review is to provide an update on the global impact of DA by presenting emerging data on drug epidemiology in adult and pediatric populations.

Results of patch testing in Acute generalized exanthematous pustulosis (AGEP): a literature review

The literature on positive patch test results in acute generalized exanthematous pustulosis (AGEP) is reviewed. 93 drugs were identified that have together caused 259 positive patch tests in 248 patients suffering from AGEP. The drug classes causing the highest number of reactions are beta-lactam antibiotics (25.9%), other antibiotics (20.8%), iodinated contrast media (7.3%) and corticosteroids (5.4%), together accounting for nearly 60% of all reactions. The highest number of reactions to individual drugs was to amoxicillin (n=36), followed by pristinamycin (n=25), diltiazem (n=14), amoxicillin-clavulanic acid (n=13), clindamycin (n=11) and iomeprol (n=8); 59 of the 93 drugs each caused a single case only. The "Top-10" drugs together caused over 50% of all reactions. The sensitivity of patch testing (percentage of positive reactions) in patients with AGEP is largely unknown, but may generally be around 50%, which also applies to pristinamycin. Patch testing in AGEP appears to be safe, although mild recurrence of AGEP skin symptoms or other rashes may occur occasionally. Clinical aspects of AGEP, including epidemiology, etiology and pathophysiology, clinical features, histology, treatment, and prognosis are briefly presented, as are diagnosing the disease and identifying the culprit drugs with patch tests, intradermal tests, in vitro tests, and challenge tests. This article is protected by copyright. All rights reserved.

The Role of Patch Testing in Evaluating Delayed Hypersensitivity Reactions to Medications

Confirming drug imputability is an important step in the management of cutaneous adverse drug reactions (CADR). Re-challenge is inconvenient and in many cases life threatening. We review the literature on ideal patch testing technique for specific CADRs. Testing should be performed approximately 3 months after the resolution of the eruption using standard patch testing techniques. Commercially available patch test preparations are available for a minority of drugs, so in most cases, testing should be performed with the drug at various recommended concentrations and in different vehicles. Testing to all known excipients, such as dyes, vehicles and preservatives is also important. Immunosuppressive medications should be discontinued or down titrated to the lowest tolerable dose to decrease the risk of false negative reactions. We provide an overview of expert recommendations and extant evidence on the utility of patch testing for identifying the culprit drug in common CADRs and for specific drug or drug classes. Overall, there appears to be significant variability in the patch test positivity of different drugs, which is likely the result of factors intrinsic to the drug such as dermal absorption (as a function of lipophilicity and molecular size) and whether the drug itself or a downstream metabolite is implicated in the immune reaction. Drugs with high patch test positivity rates include beta-lactam antibiotics, aromatic anticonvulsants, phenytoin, and corticosteroids, among others. Patch testing positivity varies both as a function of the drug and type of CADR. The sum of the evidence suggests that patch testing in the setting of morbilliform eruptions, fixed drug eruption, acute generalized exanthematous pustulosis, and possibly also drug-induced hypersensitivity syndrome, photoallergic and eczematous reactions may be worthwhile, although utility of testing may vary on the specific drug in question for the eruption. It appears to be of limited utility and is not recommended in the setting of other complex CADR, such as SJS/TEN and leukocytoclastic vasculitis.

Drug Triggers and Clinic of Acute Generalized Exanthematous Pustulosis (AGEP): A Literature Case Series of 297 Patients

Acute generalized exanthematous pustulosis (AGEP) is a rare skin reaction, commonly caused by drugs. Available evidence mostly relies on small studies or case reports. We collected published AGEP case reports and, subsequently, described the patient characteristics, suspect and concomitant drugs, time to onset, disease management, and clinical prognosis. This study included 297 AGEP patients (64.3% women) obtained from 250 published case reports or case series with individual patient data. AGEP affected patients of all ages, but the majority of patients (88.2%) were ≥25 years old. The most frequently reported suspect drugs were anti-infectives for systemic use (36.5%), particularly antibacterials for systemic use (31.0%), and especially beta-lactam antibacterials (18.3%) and macrolides (4.3%). Other frequent suspect drugs were antineoplastics (12.2%), and anti-inflammatory/anti-rheumatic products (5.2%) plus hydroxychloroquine (12.8%). Mean time to onset was 9.1 days (standard deviation SD 13.94). Some patients developed fever (64.3%) and systemic involvement (18.9%), and most patients (76.4%) received pharmacological treatment for AGEP. Seven patients died, although five of them were already critically ill prior to AGEP. In conclusion, antibiotics remain the most common suspected cause of AGEP. While case mortality rate may be up to 2.5%, disentangling the role of AGEP on the fatal outcome from the role of the preexisting health conditions remains challenging.

Cross-reactivity among iodinated contrast agents: should we be concerned?

Background

Although several papers deal with "cross-reactivity" in patients with iodinated contrast medium (ICM) hypersensitivity reactions (HSRs), there is no in-depth knowledge of this phenomenon. To define ICM-groups as potential reaction partners and to identify any potential clinical relevance in patients with ICM-HSRs.

Methods

The literature database PubMed was searched for eligible papers dealing with ICM-allergy and "cross-reactivity". The data presented by the papers was analyzed and individual patient data was extracted for re-evaluation based on a definition for both 'polyvalent reactivity' and 'cross-reactivity' as well as for chemical structure-dependent ICM-groups.

Results

Twenty-five original papers (with n=340 extracted patients) formed the study population. Incidences of polyvalent reactivity were non-significantly higher than incidences of cross-reactivity (both range from 0% to 100%). Crossover evaluation in reaction pairings (culprit ICM A with ICM B versus culprit ICM B with ICM A) showed concordance of only 30%. Data support rather non-cross-reactivity (individual reaction pattern) than cross-reactivity constellations.

Conclusions

The obtained results favour an individual reaction pattern, rather than a reactivity driven by chemical structures and so-called cross-reactivity.

DRESS and AGEP Reactions to Iodinated Contrast Media: A French Case Series

BACKGROUND

Drug reactions with eosinophilia and systemic symptoms (DRESSs) and acute generalized exanthematous pustulosis (AGEP) are potentially severe cutaneous adverse drug reactions.

OBJECTIVE

To describe the clinical findings and sensitization profiles of DRESS and AGEP patients who had been administered iodinated contrast media (ICM).

METHODS

All adult patients in the dermatologist's French Investigators for Skin Adverse Reactions to Drugs (FISARD) network diagnosed with a DRESS or AGEP highly suspected to have been caused by an ICM were included retrospectively.

RESULTS

Thirteen DRESS patients and 19 AGEP patients who had been administered ICM were included, and the median delay in DRESS and AGEP occurrence after ICM administration was short, 4 and 1 days, respectively. Five AGEP patients had systemic involvement. A high cosensitization rate (46%) was observed among the DRESS patients, mainly with beta-lactam antibiotics. Overall, 77% of our patients were sensitized to several ICM. Patch tests identified the suspected ICM for 21 cases (72%). The retrospective nature, the limited number of subjects, the absence of a control group of healthy individuals, and the lack of detailed information on previous exposure to sensitizing drugs are limitations of this study.

CONCLUSIONS

We report a large series of DRESSs and AGEPs related to ICM administration. Skin tests appear useful for diagnosis and potentially to identify alternative ICM.

Adverse reactions during procedures: Hypersensitivity to contrast agents and dyes

OBJECTIVE

This review provides an overview of the literature on hypersensitivity reactions during procedures to commonly used contrast agents and dyes. A synthesis of current knowledge on clinical symptoms, epidemiology and risk factors, pathomechanism, and management of hypersensitivity reactions to these substances is presented.

DATA SOURCES

A literature search was conducted through Medline. Included were peer-reviewed articles written in English between 2000 and 2019.

STUDY SELECTIONS

Relevant clinical studies, experimental studies, and review articles have been selected. Additionally, case reports have been included if they carried significant information about rare clinical forms of hypersensitivity reactions, disease mechanisms, or therapy.

RESULTS

An allergological workup is only indicated for patients with a history of immediate (IHR) and nonimmediate hypersensitivity reactions (NIHR) but not for toxic or unrelated adverse events. Skin tests with or without experimental cellular laboratory tests in patients with previous reactions can provide evidence for an allergic mechanism. Positive skin tests indicating allergy are more common in severe reactions. If the adverse event was allergic, skin testing of alternatives is helpful for the selection of other contrast agents for future procedures. Premedication alone may be insufficient in these cases, and breakthrough reactions occur. For nonallergic reactions, change of contrast agent and premedication is often but not always sufficient to suppress reactions.

CONCLUSION

Patients with previous NIHR or IHR, especially moderate and severe IHR, needing potential re-administration of contrast agents should be skin tested to identify an allergic mechanism as well as alternative agents to be used for future procedures.