Drug provocation tests (DPTs) of contrast media: Useful or not useful? - A narrative review.

Drug provocation tests (DPTs) are also used in some patients with a history of a contrast medium (CM)-hypersensitivity reaction. Since the use of contrast agents requires special knowledge that is present in radiology but not necessarily in allergology, this overview should close the knowledge gaps. The literature, and the package inserts of the industry dealing with DPTs in contrast hypersensitivity reactions was analyzed and the results presented. Historical analyses revealed that provocation tests were already done in the past, and called pre-testing. Due to disadvantages, this diagnostic tool was abandoned. A few years later, DPT was introduced as an innovative diagnostic procedure. The DPT has the 3 main disadvantages: a missing standardization, patients at risk (such as compromised renal function) are rarely taken into account, and a negative DPT does not exclude a subsequent CM reaction. DPTs (formerly called pre-testing) are a well-known method for diagnosing CM-related hypersensitivity reactions. Since the disadvantages of this diagnosis outweigh the advantages, we propose replacing DPT with routine contrast-enhanced imaging examination in radiology.

Immediate hypersensitivity reactions to iodinated contrast media despite drug prophylaxis-a comparative retrospective cohort study of breakthrough reactions in Bern (Switzerland) and Seoul (South Korea).

Background: Although several studies deal with breakthrough reactions (BTRs) in patients with contrast media (CM) hypersensitivity reactions, the phenomenon is still unclear. Therefore, this study aimed to analyse in depth patients with BTR in two countries. Methods: We retrospectively analysed the electronic medical records of in- and outpatients (random sample enrolment) from two academic hospitals of tertiary care (Seoul/South Korea, with a special monitoring system exclusively for CM hypersensitivity, and Bern/Switzerland, manually operated) with respect to basic epidemiological data, number of BTRs per patient, and severity grades of severity in follow-up analyses. The study period lasted from 2013 (2000 Bern) to 2017. Results: We identified 445 BTR-patients (91.5% from Seoul) with 691 BTRs (94.5% from Seoul). Most reactions were mild, 11% moderate and 3.9% severe. In Seoul, we found patients with up to 10 BTRs, and in Bern, there were only patients with one BTR. Fatal reactions or deaths did not occur. In most cases, the severity of the BTRs and of the index reactions were identical (80.8%). Mild index reactions remained constant in 90.6%. In contrast, in moderate index reactions the severity decreased/remained identically in 86.8% and increased in 13.2%. In severe index reactions, 55.6% of BTR reactions were severe again, in 44.4% the severity decreased. In 158 BTRs (22.9%) the culprit iodinated contrast medium (ICM) of the index reaction induced the BTR. In the other 482 BTRs (69.8%) the culprit ICM was changed to another non-culprit ICM. Conclusions: To the best of our knowledge, this is the largest study on patients with BTRs, and the first study showing BTRs in two centers in two countries of two continents. The main differences between the two centers result from the different hospital size, the number of patients, and the different documentation [manual (Bern) vs. electronical screening (Seoul)]. BTRs are no contraindications for further ICM-application. We recommend performing an allergy skin test as basis for the decision-making process of the next contrast-enhanced image-guided examination.

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.

Shortage of iodinated contrast media: Status and possible chances - A systematic review.

PURPOSE: Covid-19 related lockdowns have resulted in a shortage of iodinated contrast media (ICM) in 2022. Health care providers have reacted with implementing conservation strategies to stay operational without compromising patient care. Although articles describing the implemented Interventions have been published, possible chances of the shortage have not yet been mentioned in the literature. METHODS: We conducted a literature search in PubMed and Google Scholar, and analysed the background, interventions, and possible benefits of low-dose ICM regimens. RESULTS: We included 22 articles dealing with "ICM shortage" for the analysis. The delivery bottlenecks in the USA and Australia led to two different countermeasures, 1. reduction of the number of contrast-enhanced image-guided examinations and 2. reduction of the (single) ICM dose. Interventions from both groups have resulted in significant reduction of ICM usage; however, group 1 has contributed more to overall ICM reduction. As benefit of the ICM reduction, we revealed an increased safety for patients at risk (e.g. hypersensitivity reactions, contrast-induced acute kidney injury, thyroid toxic effects). CONCLUSION: The ICM shortage of 2022 has forced health care providers to implement conservation strategies to stay operational. Although there were already proposals for dose reduction before the corona pandemic and the associated supply bottlenecks, this situation led to the use of a reduced amount of contrast agent on a large scale. This presents a good opportunity to reconsider protocols and the use of contrast-enhanced imaging in general for future practice as it offers chances and advantages regarding costs, environmental impact, and patient safety.

Delayed hypersensitivity reaction after oral intake of non-ionic iodinated contrast medium.

Following intravenous contrast medium (CM) injection, a small proportion of patients acquires hypersensitivity reactions that occur either immediately or non-immediately (delayed). Although it is now claer that even oral applied CMs are able to cause adverse reactions, many radiologists as well as physicians of other disciplines, still believe that CM-application via the gastrointestinal route does not induce hypersensitivity reactions. Since this kind of misinterpretation may harm the patient, education on this topic is still necessary. Therefore, we describe a case who acquired a delayed hypersensitivity reaction following the oral intake of a non-ionic iodinated CM.

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.