Re-exposure to low osmolar iodinated contrast media in patients with prior moderate-to-severe hypersensitivity reactions: A multicentre retrospective cohort study

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.

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.

Substituting with alternative iodinated contrast medium to prevent recurrent adverse drug reactions associated with its use: a meta-analysis

OBJECTIVES

To systematically review and meta-analyze the recurrent rate of iodinated contrast medium (ICM)-associated adverse drug reactions (ADRs) and the preventive effect of using alternative ICM lacking a common carbamoyl side chain.

MATERIALS AND METHODS

A systematic literature search was conducted in the MEDLINE and EMBASE databases to identify studies that investigated the recurrence rate of ICM-associated ADRs or hypersensitivity reactions (HSRs). Studies that included patients who subsequently underwent contrast-enhanced computed tomography scans after their index reactions were included, while studies with overlapping cohorts were excluded. The first search was conducted on November 10, 2023. The pooled recurrence rate of ICM-associated ADR was determined using the DerSimonian-Laird random-effects model. Subgroup analyses were also conducted based on the substitution of ICM, with particular consideration given to the N-(2,3-dihydroxypropyl) carbamoyl side chain.

RESULTS

A total of ten original articles were included in the analysis, collectively spanning from June 2001 to March 2021. The pooled recurrence rate of ICM-associated ADR was not significantly different from that of ICM-associated HSR (16.6% [95% CI, 7.8-31.9%] vs. 15.5% [95% CI, 10.8-21.8%], p = 0.87). In the subgroup analyses, the pooled odds ratio for ICM-associated recurrent ADR when using a different ICM compared with using the same ICM was 0.31 (95% CI, 0.21-0.45), which means a 69% reduction. Moreover, the pooled odds ratio for ICM-associated recurrent ADR when substituting ICMs with different side chains compared with substituting with common side chains was 0.65 (95% CI, 0.52-0.82), which means an additional 35% reduction.

CONCLUSION

Substituting with an alternative ICM led to a 69% reduction in recurrent ADRs, with an additional 35% reduction observed when using ICM lacking a common carbamoyl side chain.

KEY POINTS

Question No standardized guidelines exist for replacing previously used iodinated contrast medium (ICM) to prevent recurrent adverse reactions. Findings Using alternative contrast medium with a different carbamoyl side chain prevents adverse drug reactions effectively. Clinical relevance This study advocates using alternative ICM without a common carbamoyl side chain to prevent recurrent adverse drug reactions in patients with a history of such events.

N-(2,3-dihydroxypropyl) carbamoyl side chain: a potentially significant factor for recurrent iodinated contrast medium-related adverse drug reactions

PURPOSE

To determine whether switching to contrast media based on the sharing of N-(2,3-dihydroxypropyl) carbamoyl side chain reduces the recurrence of iodinated contrast media (ICM)-associated adverse drug reactions (ADRs).

MATERIALS AND METHODS

This single-center retrospective study included 2133 consecutive patients (mean age ± SD, 56.1 ± 11.4 years; male, 1052 [49.3%]) who had a history of ICM-associated ADRs and underwent contrast-enhanced CT examinations. The per-patient and per-exam-based recurrence ADR rates were compared between cases of switching and non-switching the ICM from ICMs that caused the previous ADRs, and between cases that used ICMs with common and different carbamoyl side chains from ICMs that caused the previous ADRs. Downgrade rates (no recurrence or the occurrence of ADR less severe than index ADRs) were also compared. Propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) analysis were additionally performed.

RESULTS

In per-patient analysis, switching of ICM showed a lower recurrence rate (switching, 10.4% [100/965] vs. non-switching, 28.4% [332/1168]), with the adjusted odds ratio (OR) of 0.27 (95% CI: 0.21, 0.34; p < 0.001). The result was consistent in PSM (OR, 0.29 [95% CI: 0.22, 0.39]; p < 0.001), IPTW (OR, 0.28 [95% CI: 0.22, 0.36]; p < 0.001), and in per-exam analysis (5.5% vs. 13.8%; OR, 0.32 [95% CI: 0.27, 0.37]; p < 0.001). There was lower per-exam recurrence (5.0% [195/3938] vs. 7.8% [79/1017]; OR, 0.63 [95% CI: 0.47, 0.83]; p = 0.001) and higher downgrade rates (95.6% [3764/3938] vs. 93.3% [949/1017]; OR, 1.51 [95% CI: 1.12, 2.03]; p = 0.006) when using different side chain groups.

CONCLUSION

Switching to an ICM with a different carbamoyl side chain reduced the recurrent ADRs and their severity during subsequent examinations.

CLINICAL RELEVANCE STATEMENT

Switching to an iodinated contrast media with a different carbamoyl side chain reduced the recurrent adverse drug reactions and their severity during subsequent examinations.

Relationship between fasting prior to contrast-enhanced CT and adverse reaction in patients with allergies history

AIM

To examine the relationship between fasting prior to contrast-enhanced CT (CECT) and adverse reaction (AR) in patients with allergies history.

MATERIALS AND METHODS

Patients with allergies history who underwent CECT from January 2014 to December 2020 (713 cases with iodinated contrast media (ICM)-related allergy history and 27045 cases with unrelated allergies history) were retrospectively analyzed. The occurrence of ICM-related AR and patient information were recorded. The relationship between fasting and AR and emetic complications was analyzed.

RESULTS

There was no statistical difference in the overall incidence of AR and emetic complications between fasting group and non-fasting group (P>0.05) and fasting was not an influence factor for overall AR occurrence in patients with both ICM-related and unrelated allergies history. However, the incidence of severe AR in fasting group was higher than that in non-fasting group (P=0.01) in patients with unrelated allergies history. The AR incidence in fasting group was higher than that in non-fasting group (P=0.022) when receiving abdominal examinations in patients with unrelated allergies history. There was no statistical difference in the incidence of AR with different occurrence time between fasting group and non-fasting group (P>0.05) in patients with both ICM-related and unrelated allergies history.

CONCLUSIONS

Fasting was associated with higher incidence of severe AR and was associated with higher AR incidence when receiving abdominal examinations in patients with unrelated allergies history. Fasting did not have effects on the occurrence time of AR in patients with allergies history. These provided new guidance for usage of ICM in patients with allergies history.

Adverse reactions after intravascular iodinated contrast media administration and their management

Endovascular interventions and diagnostic examinations using iodinated contrast media (ICM) are standard of care in current vascular medicine. Although ICM use is generally considered safe, it may be associated with adverse reactions, vary from minor disturbances to rare, but severe life-threatening complications. This position paper of European Society of Vascular Medicine integrates current knowledge and summarizes the key information related to the use of intravascular ICM, serving as recommendation on prevention and management of acute, late, and very late adverse reactions. It should help the health professionals in all fields of vascular medicine to make decisions in daily practice for safe use of contrast media.

Preventing post-contrast acute kidney injury and hypersensitivity reactions: UK national audit

AIM

To audit UK radiology departmental protocols related to the prevention of Iodine-based contrast media (ICM) adverse drug reactions (ADRs) and to assess their compliance with the Royal College of Radiologists (RCR) endorsed Royal Australian and New Zealand College of Radiologists' 2018 Iodinated Contrast Guidelines.

MATERIALS AND METHODS

Questionnaires were sent to all UK acute National Health Service (NHS) providers treating adult patients with an audit lead registered with the RCR (162 providers encompassing 211 hospital radiology departments). The questionnaire included three main sections: renal function screening, renal protection regimens, and hypersensitivity reactions prevention and follow-up. Data collection was conducted between April and July 2022.

RESULTS

Sixty-one per cent (129/211) of departments responded, representing 67% of eligible providers. An independent imaging services provider supplied one additional set of data (n=130 overall). Of the responding departments, for post-contrast acute kidney injury (PC-AKI), 41% and 56% had the recommended risk assessment for inpatients and outpatients, respectively. Renal function testing was often over-utilised, and their results were applied improperly. Sixty-eight per cent of departments used the advised threshold for considering renal protection. For hypersensitivity reactions, 9% of departments had the correct risk assessment. Thirty-six per cent of departments had the correct risk mitigation protocol for identified high-risk patients. The documentation and follow-up for hypersensitivity reactions were similarly inadequate.

CONCLUSION

Local protocols on preventing ICM ADRs were largely non-compliant with RCR guidelines. Departments need to update their protocols in line with current evidence to avoid iatrogenic morbidity or unnecessary tests and over-precaution.

Substitution with Low-Osmolar Iodinated Contrast Agent to Minimize Recurrent Immediate Hypersensitivity Reaction

Background The recurrence of hypersensitivity reaction (HSR) to low-osmolar iodinated contrast media (LOCM) remains challenging despite premedication and substitution of the LOCM. Purpose To determine the optimal practical preventive strategy for LOCM substitution in patients with a history of prior immediate HSR to LOCM. Materials and Methods In a retrospective study, patients with an immediate HSR to LOCM before February 2020 and who underwent subsequent exposure to LOCM until March 2021 were enrolled in five tertiary referral hospitals in South Korea. The association of recurrence of an HSR after subsequent LOCM exposures was assessed using multivariate general estimating equation analysis according to age, sex, the severity of the index HSR, premedication, and substituting LOCM based on common carbamoyl side chains, including the N-(2,3-dihydroxypropyl)-carbamoyl and N-(2,3-dihydroxypropyl)-N-methyl-carbamoyl moieties. Results The evaluation included 3800 subsequent LOCM exposures in 1066 patients (mean age, 56.2 years ± 13.5 [SD]; 567 [53%] female and 499 [47%] male patients). The general estimating equation analysis, using 1:1 propensity score matched data for age, sex, HSR severity, and LOCM selection, showed that premedication with corticosteroids significantly reduced recurrent HSR (odds ratio [OR], 0.72; 95% CI: 0.52, 1.00; P = .049). The change to another LOCM with a common side chain had a similar recurrence rate as using the same LOCM (OR, 0.98; 95% CI: 0.64, 1.50; P = .93), whereas the use of a different LOCM without a common side chain significantly lowered HSR recurrence (OR, 0.51; 95% CI: 0.37, 0.69; P < .001) in multivariate general estimating equation analysis. Substitution of an LOCM without a common side chain was effective regardless of the index HSR severity but was more pronounced in moderate-to-severe reactions (OR, 0.30; 95% CI: 0.16, 0.55; P < .001). Conclusion For patients with a previous immediate HSR of any severity to LOCM, alternative LOCM without a common carbamoyl side chain reduced recurrent HSR during subsequent exposures. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by McDonald in this issue.

Clinical outcomes and management of contrast hypersensitivity in patients requiring repeated computed tomography imaging

Introduction

In collaboration with the Department of Rheumatology, Allergy and Immunology, our study aims to review the outcomes of and propose an improved workflow for the management of patients with prior hypersensitivity reactions to iodinated contrast media (ICM).

Method

Outpatients coming for contrast-enhanced computed tomography (CECT) were stratified into 3 categories (definite, unconfirmed and inaccurate) based on likelihood of their contrast hypersensitivity label. Patients could be offered a different ICM, receive the same ICM, or be referred to an allergist for further evaluation. There were 4 outcomes: (1) alternative ICM tolerated; (2) same ICM tolerated again; (3) patient developed a hypersensitivity reaction to either alternative or original ICM; and (4) CECT was deferred until assessment by an allergist. Comparison was made pre- and post-intervention to see if patient outcomes were improved.

Results

There were 132 patients who made a total of 154 visits (90.3% had documented contrast hypersensitivity). Post-intervention, the number of visits postponed for premedication decreased (81.0% to 34.7%). There was a reduction in hypersensitivity reactions (from 42.9% to 14.3%). Of the 12 patients assessed by the allergist, 6 could continue using the same or alternative ICM, 4 were advised to abstain from further contrast administration and 2 were pending testing with a third agent.

Conclusion

Active intervention by the radiologist can decrease the number of postponed, converted or cancelled CECT studies as well as reduce the number of adverse allergic-like events. Direct collaboration between radiologist and allergist for specific cases may be helpful in patients who will likely need future/repeated CECTs.

Contrast Agent Selection to Prevent Recurrent Severe Hypersensitivity Reaction to Iodinated Contrast Media Based on Nationwide Database

OBJECTIVE

To investigate the incidence of severe iodinated contrast media (ICM)-related hypersensitivity reaction (HSR) and to find the optimal alternative ICM to reduce the risk of severe HSR recurrence.

METHODS

We retrospectively reviewed 23,383,183 cases of ICM administration between January 2015 and December 2019 from the nationwide health insurance database. We classified ICMs based on generic profiles and the presence of N-(2,3-dihydroxypropyl) carbamoyl side chains. The incidence of severe and recurrent severe HSRs was calculated, and χ2 tests were performed to compare the prevalence of severe HSR according to ICM groups. In addition, logistic regression analyses were used to assess differences between ICM groups.

RESULTS

The incidence of severe HSRs was 1.92% (450,067 of 23,282,183). Among 1,875,245 individuals who received ICM twice on different days, severe HSR occurred in 40,850 individuals, and severe HSR recurred in 3319 individuals (8.12%). The risk of recurrence significantly decreased when the ICM changed (9.24% vs 7.08%, P < 0.001), especially when the ICM changed to one with a different side chain (6.74%, P < 0.001). In addition, compared with the reuse of the culprit agent, using combinations of iobitridol/iohexol (odds ratio [OR], 0.696; P = 0.04), iohexol/iopamidol (OR, 0.757; P = 0.007), iopamidol/iohexol (OR, 0.447; P < 0.001), and ioversol/iohexol (OR, 0.683; P = 0.04) reduced the risk of recurrence of severe HSR.

CONCLUSIONS

Changing the culprit ICM to that with a different side chain can reduce severe HSR recurrence. The optimal choice of an alternative ICM depends on the causative agent.

American Society of Regional Anesthesia and Pain Medicine contrast shortage position statement

The medical field has been experiencing numerous drug shortages in recent years. The most recent shortage to impact the field of interventional pain medicine is that of iodinated contrast medium. Pain physicians must adapt to these changes while maintaining quality of care. This position statement offers guidance on adapting to the shortage.

Indian College of Radiology and Imaging Consensus Guidelines on Interventions in Pancreatitis

Acute pancreatitis (AP) is one of the common gastrointestinal conditions presenting as medical emergency. Clinically, the severity of AP ranges from mild to severe. Mild AP has a favorable outcome. Patients with moderately severe and severe AP, on the other hand, require hospitalization and considerable utilization of health care resources. These patients require a multidisciplinary management. Pancreatic fluid collections (PFCs) and arterial bleeding are the most important local complications of pancreatitis. PFCs may require drainage when infected or symptomatic. PFCs are drained endoscopically or percutaneously, based on the timing and the location of collection. Both the techniques are complementary, and many patients may undergo dual modality treatment. Percutaneous catheter drainage (PCD) remains the most extensively utilized method for drainage in patients with AP and necrotic PFCs. Besides being effective as a standalone treatment in a significant proportion of these patients, PCD also provides an access for percutaneous endoscopic necrosectomy and minimally invasive necrosectomy. Endovascular embolization is the mainstay of management of arterial complications in patients with AP and chronic pancreatitis. The purpose of the present guideline is to provide evidence-based recommendations for the percutaneous management of complications of pancreatitis.

Differences in the Recurrence Rate of Immediate Adverse Drug Reactions According to the Components of Alternative Contrast Media: Analysis of Repetitive Computed Tomography Cases in a Single Tertiary Hospital

INTRODUCTION

The recurrence rates of immediate adverse drug reactions (ADRs) to the alternative radiocontrast media (RCM) are not well known. Previous studies suggest selection of alternative RCM considering carbamoyl side chains; however, its usefulness for preventing the recurrence of ADRs has not been clearly verified.

OBJECTIVE

The aim of this study was to verify the recurrence rate of immediate ADRs according to the alternative RCM.

METHOD

This retrospective study analyzed 6420 contrast-enhanced computed tomography (CT) cases of 2009 patients registered in the ADR system from 861,664 CT cases in a single tertiary hospital between 2015 and 2020. Iohexol, iopromide, iobitridol, and iopamidol were used for CT. According to the carbamoyl side chains present, iohexol belongs to group 1, iopromide belongs to groups 1 and 2, iobitridol belongs to group 2, and iopamidol belongs to group 3.

RESULTS

Replacing iobitridol with iopamidol (odds ratio [OR] 2.595, 95% confidence interval [CI] 1.48-4.550) or iopromide (OR 3.354, 95% CI 1.420-7.926) as the subsequent RCM was associated with increased recurrence, while replacing iopamidol with iobitridol (OR 0.506, 95% CI 0.282-0.908) and iopromide with iohexol (OR 0.355, 95% CI 0.177-0.711) was associated with decreased recurrence. Other changes did not influence the recurrence of ADRs.

CONCLUSIONS

The recurrence of immediate ADRs increased in certain RCM combinations of preceding and subsequent CT scans, and the RCMs did not show cross-reactivity. Therefore, the clinical benefit of the alternative RCM considering cross-reactivity is limited. This result suggests that the side chains of RCM do not have an important role in the recurrence of immediate ADRs.

Successful Adrenal Vein Sampling Using Dexamethasone Premedication in Patients With Iodine Contrast Media Allergy

Context

Preparation of patients with iodine contrast media (ICM) allergy who require adrenal vein sampling (AVS) to establish source of aldosterone excess of their confirmed primary aldosteronism (PA) is controversial. Usual premedication with high-dose prednisone can interfere with cortisol determinations, possibly altering the aldosterone to cortisol ratios for the identification of lateralized aldosterone excess.

Objective

We aimed to evaluate the efficacy and safety of premedication with high-dose dexamethasone to perform AVS in patients with ICM.

Methods

One hundred and seventy-seven consecutive patients with confirmed PA who underwent bilateral simultaneous basal and post-ACTH bolus AVS at our center between January 2010 and December 2020 were retrospectively analyzed for history of ICM allergy. A total of 7 patients (4%) with previous allergic reactions to ICM were prepared with 3 doses of 7.5 mg dexamethasone premedication rather than the usual 50 mg of prednisone.

Results

No breakthrough allergic reactions were reported in the 7 patients. Despite adequate serum cortisol suppression following dexamethasone, the basal and post-ACTH selectivity index were respectively &gt; 2 and &gt; 5 bilaterally in all patients, confirming adequate cannulation of both adrenal veins. Four patients had lateralized ratios (A/C ratio &gt; 2 basally and &gt; 4 post-ACTH), while 3 had bilateral source during AVS study. In the 3 patients undergoing unilateral adrenalectomy for lateralized source and contralateral suppression and adequate follow-up data, cure of PA was achieved at mean 58 months postoperatively.

Conclusion

AVS using dexamethasone premedication is safe and accurate for diagnosing the source of aldosterone excess in patients with PA and ICM allergy.

Implementation of a Semistructured Clinical Event Documentation Tool for Acute Adverse Contrast Reactions

PURPOSE

To improve the efficiency and accuracy of clinicians documenting acute clinical events related to contrast agent administration using a web browser-based semistructured documentation support tool.

METHODS

A new tool called CISaR (Contrast Incident Support and Reporting) was developed to enable radiologists responding to contrast reactions to document inciting contrast class, type of event, severity of contrast reaction, and recommendation for future contrast use. Retrospective analysis was conducted of all CT and MRI examinations performed between February 2018 and December 2019 across our hospital system with associated contrast reaction documentation. Time periods were defined as before tool deployment, early adoption, and steady-state deployment. The primary outcome measure was the presence of event documentation by a radiologist. The secondary outcome measure was completeness of the documentation parameters.

RESULTS

A total of 431 CT and MRI studies with reactions were included in the study, and 50% of studies had radiologist documentation during the pre-CISaR period. This increased to 66% during the early adoption period and 89% in the post-CISaR period. It took approximately 9 months from the introduction of CISaR to reach full adoption and become the main method for adverse contrast reaction documentation. The percentage of radiologist documentation that detailed provoking contrast agent class, severity of reaction, reaction type, and future contrast agent recommendation all significantly increased (P < .0001), with greater than 95% inclusion of each element.

CONCLUSION

The implementation of a semistructured electronic application for adverse contrast reaction reporting significantly increased radiologist documentation rate and completeness of the documentation.

Diagnosis and Prevention of Hypersensitivity Reactions to Iodinated Contrast Media

Iodinated contrast media (ICM) have become one of the major causes of drug hypersensitivity reactions (HSRs) related to increasing numbers of ICM-based radiological imaging procedures. Strategies for diagnosing and preventing ICM-induced HSRs have not been uniformly standardized yet. However, advances have been made based on the results of recent research. A previous history of hypersensitivity to ICM is the most significant risk factor for developing HSR by ICM. Avoidance of culprit agents and premedication is the main strategy to prevent recurrences of HSRs in high-risk patients. In addition, we strongly recommend identifying sensitized ICM using skin tests to determine immunoglobulin E-mediated or delayed-type allergy and to guide the choice of an alternative contrast agent. ICM provocation test procedures have been established and are helpful in selected cases. In this paper, we review how to evaluate patients who have experienced immediate or delayed HSRs caused by ICM to minimize the risk of recurrence and discuss unmet needs that require further research.

Clinical implication of detecting sensitization to iodinated radiocontrast media in the basophil activation test by flow cytometry

The use of iodinated radiocontrast media is necessary for visualization. A number of patients have adverse effects of various nature and severity when these drugs are administered. Routine allergy tests do not provide adequate diagnosis of reactions to drugs in this group. The aim of this work is to assess the capabilities of the basophil activation test to confirm sensitization to non-ionic iodinated radiocontrast media, as well as to select a safe alternative drug in patients with a burdened history. Basophil activation test by flow cytometry was performed in 184 patients The Nikiforov Russian Centre of Emergency and Radiation Medicine» EMERCOM of Russia and 32 volunteers using ultravist, omnipack, and optiray. The presence of sensitization was assessed based on the basophil activation index, as well as spontaneous and anti-IgE antibody-induced activation of basophils and the population of T-lymphocytes type 2 immune response. The volunteers showed no sensitization to iodinated radiocontrast media. In patients with a medium degree of hypersensitivity reaction in vivo, in vitro sensitization to drugs was detected 4 times more often than in patients with a mild degree (51% versus 13.5%). In patients with systemic reactions to the administration of a known drug, in vitro sensitization was confirmed in 86% of cases, while the frequency of detection of sensitization to drugs did not differ. Spontaneous activation of basophils in patients and type 2 T-lymphocytes were 2 times higher than in volunteers. Patients were more likely to have low (less than 30%) activation of basophils for anti-IgE antibodies. The specificity of the basophil activation test with iodinated radiocontrast media was 100% with a sensitivity of 94.1%. Most patients were able to select a non-sensitizing contrast. Inclusion in the algorithm of spontaneous and anti-IgE antibody-induced activation of basophils and a population of T-lymphocytes type 2 immune response will allow the doctor to carry out a personalized approach to the management of patients with a burdened history.

Shelling the myth: allergies to Iodine containing substances and risk of reaction to Iodinated contrast media

PURPOSE

In excess of 100 million procedures using iodinated radio-contrast media are conducted each year. There is a common misunderstanding regarding the links between allergy to iodinated substances and the risk of allergic reaction to intravenous iodinated contrast agents. These perceived risks are managed via administration of corticosteroids or avoidance of iodinated contrast altogether.

METHODS

An extensive review of published literature on scientific databases and international guidelines was conducted in order to inform the research question. A questionnaire was formulated and distributed to hospital doctors in four tertiary centres. Within this questionnaire, hospital doctors were presented with six different scenarios of bona fide allergy to iodinated substances (e.g. shellfish) and asked to select the treatment response option which they deemed to be the most suitable from a choice of three (standard contrast scan/delay scan with pre-medication/change to non-contrast scan).

RESULTS

Eighty-seven questionnaire responses were received. Contrast (standard protocol) was the most appropriate regimen in the setting of all the listed allergies. This was identified correctly by 76%, 69%, 44%, 32%, 18% and 14% for kiwi, fish, poly-food, shellfish, betadine and tincture of iodine allergies, respectively.

CONCLUSIONS

There is a lack of understanding amongst local junior medical staff regarding administration of iodinated contrast media to patients with a history of allergy to iodinated substances. These misconceptions may potentiate the unnecessary usage of pre-medication and ordering of non-contrast scans in the setting of a gold-standard enhanced scan. Findings from this study suggest that there is a need for future education efforts targeted during the basic specialty training stage.

Adrenal Vein Sampling in a Patient With Primary Hyperaldosteronism and Severe Contrast Allergy

We report on a case of a 50-year-old female patient with primary hyperaldosteronism, in whom adrenal venous sampling was required to differentiate between unilateral and bilateral disease. Because of a history of severe allergy to iodinated contrast media, premedication with glucocorticoids was indicated. Exogenous glucocorticoids, however, can affect measurements of serum cortisol. To avoid this potential confounding effects on the cortisol assay, we decided to use dexamethasone instead of prednisolone or hydrocortisone. A high-dose adrenocorticotropin (ACTH) stimulation test with the simultaneous use of dexamethasone revealed an adequate adrenal cortisol response. ACTH-stimulated adrenal venous sampling showed reliable results, which provided a solid basis for further clinical decision-making.

Diagnosing and Managing Patients with Reactions to Radiocontrast Media

Purpose of the review

Iodinated radio contrast media (RCM) belong to the most common elicitors of drug hypersensitivity reactions (HR). Urticaria or anaphylaxis may occur ≤ 1(−6) hour(s) (immediate HR) and exanthems (non-immediate HR) develop > 6 h after application of RCM. Evidence for an immunologic mechanism of RCM HR against the different RCM benzene ring molecules and the benefit of allergological testing in patients with previous hypersensitivity reactions is progressively increasing.

Recent findings

Positive skin tests can confirm allergy in patients with previous reactions to RCM and help to select alternative better tolerated RCMs. Severe hypersensitivity reactions are mainly caused by an allergic mechanism, whereas the majority of non-severe reactions appear to be non-allergic. Skin testing is highly recommended to help identify allergic hypersensitivity reactions and to select alternatives. Using structurally different RCM is more effective than premedication for the prevention of future reactions. Drug provocation tests to RCM have been increasingly used, but are not yet standardized among different centers.

Summary

In patients with previous severe hypersensitivity reactions to RCM, skin testing is recommended. For future RCM-enhanced examinations in patients with previous reactions, structurally different, skin test-negative preparations should be applied. Drug provocation tests do confirm or exclude RCM hypersensitivity or may demonstrate tolerability of alternative RCMs.

Patients have very limited knowledge of their contrast allergies

PURPOSE

To quantify patients' knowledge of their iodinated contrast allergies; and to compare this data to literature estimates of patient knowledge of other medication allergies.

METHODS

Using a key word search of 15,715 patients undergoing a total of 19,043 CT studies over a six-month period, a cohort of 307 adult patients claiming prior allergic reaction to iodinated intravenous contrast was identified. A patient questionnaire with the CT studies inquired about the specifics of their contrast allergy, including the symptoms of their prior allergic reaction; when and where the reaction occurred; and if patients could name the contrast agent to which they claim to be allergic.

RESULTS

In the cohort of 307 patients claiming a prior allergic reaction to iodinated contrast, 86.6% could describe their prior allergic reaction symptoms. Only 36.8% could provide an approximate year of the reaction, with an additional 6.5% claiming that their reactions were remote, for a total of 43.3% providing some information when their reaction occurred. 56.7% provided no information on the year of their reaction. 40.7% named either the facility or the city where the reaction occurred, while 59.3% could not. Only 5 of 307 (1.6%, p < 0.00001) could name the contrast agent to which they believed they were allergic.

CONCLUSION

Other studies have reported inconsistencies, limited documentation, and limited ability to confirm patients' pharmacologic allergies, estimating that patients prior to pharmacist consultation are approximately 60-70% accurate in listing their drug allergies by name. Nevertheless, patients' knowledge of their iodinated contrast allergies is markedly more limited when compared to expected patient knowledge of medication allergies in general.

Prevention of Allergic-like Reactions at Repeat CT: Steroid Pretreatment versus Contrast Material Substitution

Background It is unclear whether steroid premedication is an effective means of preventing repeat allergic-like reactions in high-risk patients with a previous allergic-like reaction to iodinated contrast material (ICM). Purpose To compare the effectiveness of ICM substitution (ie, using iohexol in a patient with a previous iopromide reaction) with 12- and 2-hour steroid premedication for preventing repeat acute allergic-like reactions in high-risk patients. Materials and Methods This retrospective study identified all high-risk (ie, having a previous allergic-like reaction) adult and pediatric patients who underwent a contrast-enhanced CT examination at the institution from June 1, 2009, to May 9, 2017. Prophylactic treatments and repeat reactions were identified using chart review. The effectiveness of prophylactic treatments on repeat reaction rates was examined with multivariable regression models that used generalized estimating equations. Results A total of 1973 high-risk patients who underwent 4360 subsequent ICM-enhanced CT examinations were included. Of the 4360 examinations, a total of 280 allergic-like reactions occurred (6%) in 224 of the 1973 patients (11% of patients), with only 19 of 280 reactions (7%) that were more severe than the previous reaction being demonstrated. After adjustment, patients who received a different ICM with and without steroid premedication had a significantly lower rate of repeat reactions than did patients who received steroid premedication and the same ICM (same ICM and steroid premedication: 80 of 423 examinations [19%]; different ICM and no steroid premedication: 10 of 322 examinations [3%]; odds ratio [OR], 0.14 [95% CI: 0.06, 0.33]; P < .001; different ICM and steroid premedication: five of 166 patients [3%]; OR, 0.12 [95% CI: 0.04, 0.36]; P < .001). When examining the first scan only, patients who received the same ICM had a similar risk of repeat reactions regardless of whether they received steroid premedication (steroid premedication: 44 of 172 patients [26%] vs no premedication: 73 of 298 patients [25%]; OR, 1.00 [95% CI: 0.64, 1.57]; P = .99). Conclusion In this cohort, using an iodinated contrast material (ICM) substitution was more effective for preventing repeat allergic-like reactions than using steroid premedication and the same ICM that caused the previous reaction. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Davenport and Weinstein in this issue.

Finding the Optimal Alternative for Immediate Hypersensitivity to Low-Osmolar Iodinated Contrast

OBJECTIVES

Avoiding culprit agents is recommended for subjects who have had previous hypersensitivity reaction (HSR) to low-osmolar contrast media (LOCM). However, the guidelines for choosing optimal alternatives have not been determined. We investigated the outcomes of reexposure in patients with previous immediate HSRs to provide a safe option.

MATERIALS AND METHODS

The outcomes of reexposure were assessed in a cohort with previous LOCM-associated HSR based on skin testing results and the presence of a common N-(2,3-dihydroxypropyl) carbamoyl side chain.

RESULTS

Among 482 skin tests, 38.7% (31/80), 45.8% (99/216), and 64.0% (119/186) of mild, moderate, and severe index HSRs showed positivity to at least 1 LOCM, of which 62.8% showed positivity to at least 2 different LOCM. The overall recurrent HSRs were reduced from 43.8% upon reexposure to the culprit LOCM to 12.3% upon using nonculprit skin test negative LOCM (P = 0.004); those with severe index HSRs exhibited a significant reduction (11.3% vs 100%), but those with non-severe HSRs to LOCM did not. In subjects with severe index HSRs, the skin test cross-reactivity between LOCM was associated with sharing the common side chain (20.7% vs 11.5%, P = 0.003), and the recurrence rate of HSRs was effectively reduced by avoiding the common side chain (24.0% vs 7.8%, P = 0.039). However, these differences were not observed in those with non-severe index HSRs.

CONCLUSIONS

In patients who experienced a severe index HSR to LOCM, skin test negative LOCM without a common side chain could be suggested as an option for safe reexposure.

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.

Mortality rate of birds following intravenous administration of iodinated contrast medium for computed tomography

OBJECTIVE

To identify potential risk factors for death following IV or intraosseous (IO) administration of contrast medium in birds undergoing CT scans.

ANIMALS

120 birds that underwent 134 contrast-enhanced CT scans.

PROCEDURES

Medical records of birds of any species that underwent a CT scan which included administration of nonionic iodinated contrast medium from June 2013 to February 2020 were included. Information on birds and use of contrast medium was extracted from the medical records as well as information on deaths following IV or IO administration of contrast medium.

RESULTS

6 birds died shortly following administration of contrast medium. Necropsies were performed in 3 birds (2 cockatiels and 1 macaw), and all had lesions associated with the respiratory tract. When body weight was used as a binary variable to compare odds of death between small birds (≤ 150 g [0.33 lb]) and large birds (> 150 g), small birds had a 97-fold increased odds (OR, 97.5; 95% CI, 9.8 to 966.0) of dying following contrast medium administration. Following 131 CT scans with contrast medium administration (3 scans were excluded because of perivascular or subcutaneous leakage of contract medium), small birds had a mortality rate of 45.4% (5/11), compared with a mortality rate of 0.8% (1/120) for large (> 150 g) birds. Other variables (ie, sex, age, anesthesia or sedation, sedation protocol, and type of contrast medium) were not significantly associated with death after contrast medium administration.

CONCLUSIONS AND CLINICAL RELEVANCE

Although the administration of contrast medium cannot be conclusively confirmed as the cause of death in these birds, the high mortality rate for small birds coupled with the temporality of the event following contrast medium administration justifies the cautious use of contrast medium in small sick psittacine birds.

Acute Urticaria in Inpatients Undergoing Non-emergent Coronary Angiography With Corticosteroid Prophylaxis: A Retrospective Study

Background and Aims: Acute urticaria (AU) is the most frequently reported immediate hypersensitivity reaction in skin by administration of iodinated contrast media (ICM). We aimed to establish the pattern and identify the risk factors of AU among inpatients undergoing non-emergent coronary angiography (CAG) with prophylactic corticosteroids in China.

Methods: Medical records of 19,326 adult inpatients undergoing non-emergent CAG with prophylactic methylprednisolone in 2013–2019 were retrospectively investigated. AU was identified within 1 h post-ICM administration, and diffuse involvement was defined when wheals occur in two or more body parts, including the back, abdomen, chest, and extremities. Age- and sex-matched inpatients (1:4) without AU were randomly selected for assessment of risk factors.

Results: Approximately 0.8% of CAG inpatients had AU, including 101 diffuse and 64 limited form. The diffuse AU was more common in settings of non-diagnostic CAG, iohexol used, average ICM injection≥3 ml/min, recurrent CAG, and past history of immediate hypersensitivity to ICM. Inpatients with preexisting allergies, decreased evaluated glomerular filtration rate, and increased high sensitivity C reactive protein or neutrophil-to-lymphocyte ratio prior to CAG had a higher probability of AU (odds ratio >1, P < 0.05 for all variables). All AU inpatients complained of pruritus, and mild itching predominated. AU dissipated in several days under treatment of ebastine or levocetirizine 10 mg/daily, but ebastine showed superiority.

Conclusions: ICM-induced AU is not uncommon in non-emergent CAG inpatients with prophylactic methylprednisolone. Preexisting allergies, renal dysfunction, and mild inflammation are high-risk factors, and antihistamine monotherapy is a favorable candidate for ICM-related AU.

Iodine allergy: Common misperceptions

Disclaimer

In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

Purpose

The current evidence regarding iodine-containing compounds and iodine allergy cross-reactivity is reviewed.

Summary

Iodine is an essential human nutrient found in the thyroid gland. It is used in the synthesis of the thyroid hormones thyroxine and triiodothyroxine. Patients who report having adverse reactions to iodine-containing substances are often labelled as having an “iodine allergy,” which can result in delays in care or patients being denied essential ICM or other iodine-containing drugs. A literature review was conducted to evaluate the evidence regarding iodine allergy and iodine-containing drugs. Of 435 articles considered potentially appropriate for full review (plus 12 additional articles included on the basis of references from the eligible articles), 113 could not be obtained. After exclusion of 353 articles that did not meet all inclusion criteria, the remaining 81 articles were included in the review. The results of the literature review indicated that iodine has not been shown to be the allergen responsible for allergic reactions to iodinated contrast media, amiodarone, povidone-iodine, and other iodine-containing compounds.

Conclusion

There is a lack of evidence to support cross-reactivity between iodine-containing compounds in so called iodine-allergic individuals.

The Use of Contrast Agents in Interventional Pain Procedures: A Multispecialty and Multisociety Practice Advisory on Nephrogenic Systemic Fibrosis, Gadolinium Deposition in the Brain, Encephalopathy After Unintentional Intrathecal Gadolinium Injection, and Hypersensitivity Reactions

This Practice Advisory presents a comprehensive and evidence-based set of position statements and recommendations for the use of contrast media in interventional pain procedures. The advisory was established by an international panel of experts under the auspices of 11 multinational and multispecialty organizations based on a comprehensive review of the literature up to December 31, 2019. The advisory discusses the risks of using gadolinium-based contrast agents. These include nephrogenic systemic fibrosis, gadolinium brain deposition/retention, and encephalopathy and death after an unintentional intrathecal gadolinium injection. The advisory provides recommendations on the selection of a specific gadolinium-based contrast agent in patients with renal insufficiency, those who had multiple gadolinium-enhanced magnetic resonance imaging examinations, and in cases of paraspinal injections. Additionally, recommendations are made for patients who have a history of mild, moderate, or severe hypersensitivity reactions to contrast medium.

Fidelity of Electronic Documentation for Reactions Prompting Premedication to Iodinated Contrast Media

PURPOSE

The aims of this study were to assess the fidelity of electronic health record documentation prompting premedication to iodinated contrast media and to determine the appropriateness of administered premedication on the basis of that documentation.

METHODS

In this retrospective quality assurance cohort study, medication adverse events recorded in electronic health records between January 1, 2018, and August 31, 2019, to "iodine," "iodine-containing products," and "iodinated contrast media" were identified (N = 4,309); entries missing documentation (n = 1,651) and breakthrough reactions (n = 22) were excluded. Reaction description, severity, and free-text comments were used to categorize each entry as concordant (documentation matches recorded severity per the ACR Manual on Contrast Media version 10.3), discordant (description-severity mismatch, agent unrelated to iodinated contrast media, not a hypersensitivity reaction), or unclear. A subset of patients undergoing premedication was identified, and premedication was categorized as appropriate, inappropriate, or unsure on the basis of the index reaction using the aforementioned framework. Descriptive statistics were calculated.

RESULTS

There were 2,636 adverse event entries in 2,441 patients: 59.9% (1,578 of 2,636) were classified as concordant, 30.2% (797 of 2,636) as discordant (n = 377 not a hypersensitivity reaction, n = 317 description-severity mismatch, and n = 103 unrelated agent), and 9.9% (n = 261) as unclear documentation. For the premedicated subset, concordance classification was feasible for 202 unique patients premedicated 335 times. Premedication was appropriate in 72% (240 of 335) and inappropriate in 22% (73 of 335); 17% of premedication events (56 of 335) were inappropriately administered for a prior physiologic reaction.

CONCLUSIONS

Premedication prompts in the electronic health record are often erroneous because of inaccurate coding, incomplete data, and reaction misclassification. These errors result in inappropriate premedication for a substantial minority of patients.

Safety Analysis of Iobitridol as a Nonionic Contrast Medium: A Postmarketing Multicenter Surveillance Study With 94,960 Patients Almost 20 Years After Introduction

OBJECTIVES

Our study sought to reevaluate the safety and diagnostic efficacy of iobitridol as a nonionic contrast medium after almost 20 years of use.

MATERIALS AND METHODS

This noninterventional postmarketing surveillance noncontrolled, multicenter (168 centers in Germany) study enrolled 94,960 patients receiving intravenous or intra-arterial iobitridol. The majority of the adjusted population (n = 92,550, 98.2%) underwent either computed tomography examination (n = 46,502, 49.3%) or intravenous urography (n = 46,048, 48.8%). A standardized questionnaire was used to ascertain patient's information, known risk factors, renal function status, premedication, type of examination, injection of contrast agent, imaging quality, diagnostic value, and safety.

RESULTS

A total of 469 patients (0.49%) experienced an adverse event (AE), and 24 patients (0.025%) reported a serious AE (SAE). All patients recovered and no fatal event occurred. The prevalence of AE was significantly higher in patients with at least one risk factor, with premedication, with a history of AE, in female and patients younger than 60 years old (P < 0.05). Presence of at least one risk factor is the only predictive factor for the prevalence of SAE (P = 0.042). In patients with a history of AE, premedication did not significantly lower the AE rate (P = 0.737). No statistically significant difference in the prevalence of AE between the different combination of cortisone and/or antihistamines as pretreatment was found.

CONCLUSIONS

Iobitridol is a safe contrast medium with a high tolerability and efficacy. Presence of risk factors such as cardiovascular diseases, allergies, or asthma was the only significant predictive factor for an AE and an SAE. Premedication did not significantly lower the occurrence of an AE and an SAE.

SIRM-SIAAIC consensus, an Italian document on management of patients at risk of hypersensitivity reactions to contrast media

Hypersensitivity reactions (HRs) to contrast media (CM) can be distinguished in immune-mediated (including allergic reactions) and non-immune-mediated reactions, even if clinical manifestations could be similar. Such manifestations range from mild skin eruptions to severe anaphylaxis, making it important for radiologists to know how to identify and manage them. A panel of experts from the Società Italiana di Radiologia Medica e Interventistica (SIRM) and the Società Italiana di Allergologia, Asma e Immunologia Clinica (SIAAIC) provided a consensus document on the management of patients who must undergo radiological investigations with CM. Consensus topics included: the risk stratification of patients, the identification of the culprit CM and of a safe alternative by an allergy workup, as well as the use of premedication and the correct procedure to safely perform an elective (i.e., scheduled) or urgent examination. The most important recommendations are: (1) in all patients, a thorough medical history must be taken by the prescribing physician and/or the radiologist to identify at-risk patients; (2) in patients with hypersensitivity reactions to CM, the radiologist must consider an alternative, non-contrast imaging study with a comparable diagnostic value, or prescribe a different investigation with another class of CM; (3) if such options are not feasible, the radiologist must address at-risk patients to a reference centre for an allergy evaluation; (4) if timely referral to an allergist is not viable, it is recommended to use a CM other than the responsible one, taking into account cross-reactivity patterns; in the case of patients with histories of severe reactions, the presence of an anesthesiologist is also recommended and a premedication is suggested.

Shared functional neural substrates in Parkinson's disease and drug-induced parkinsonism: association with dopaminergic depletion

While drug-induced parkinsonism (DIP) is mainly caused by blockage of the dopaminergic pathway, multiple neurotransmitter systems besides the dopaminergic system are involved in Parkinson’s disease (PD). Therefore, alterations found in both DIP and PD might be manifestations of dopaminergic dysfunction. To prove this hypothesis, we aimed to define the areas commonly involved in DIP and PD and determine whether the overlapping areas were associated with the dopaminergic system. 68 PD patients, 69 DIP patients and 70 age-and sex-matched controls underwent resting-state functional MRI (rsfMRI). Regional homogeneity (ReHo), amplitude of low-frequency fluctuation (ALFF) and fractional ALFF were calculated and compared. Afterwards, we compared mean rsfMRI values extracted from the overlapping areas with uptake quantitatively measured on dopamine transporter (DAT) images and neuropsychological test results. Compared to the controls, both PD and DIP patients revealed altered rsfMRI values in the right insular cortex, right temporo-occipital cortex, and cerebellum. Among them, decreased ALFF in the right insular cortex and decreased ReHo in the right occipital cortex were correlated with decreased DAT uptake in the caudate as well as executive, visuospatial, and language function. Increased ReHo in the cerebellum was also correlated with decrease DAT uptake in the posterior and ventral anterior putamen, but not with cognitive function. In conclusion, the insular cortex, occipital cortex, and cerebellum were commonly affected in both PD and DIP patients and might be associated with altered dopaminergic modulation.

Preventive Effect of Changing Contrast Media in Patients With A Prior Mild Immediate Hypersensitivity Reaction to Gadolinium-Based Contrast Agent

OBJECTIVES

Currently, the prevention of recurrent immediate hypersensitivity reactions (HSRs) to contrast media (CM) requests premedication and changing the culprit contrast agent. However, strategies for the prevention of immediate HSRs to gadolinium-based magnetic resonance contrast agents (GBCAs) have not yet been established. This study aimed to evaluate the effectiveness of changing the contrast agent and single-dose premedication for HSR recurrence prevention in patients with a history of mild immediate HSR to GBCA.

MATERIALS AND METHODS

The outcomes of patients with mild immediate HSR to GBCA who subsequently underwent enhanced magnetic resonance imaging between October 2012 and July 2017 were analyzed. The institutional CM monitoring system was retrospectively reviewed, and data on the application of premedication and choice of CM were obtained. Gadolinium-based magnetic resonance contrast agents were classified into 3 classes according to their molecular structure (macrocyclic ionic, macrocyclic nonionic, and linear ionic). Intravenous chlorpheniramine 4 mg, 30 minutes before the GBCA administration, or intravenous methylprednisolone sodium succinate 40 mg plus chlorpheniramine 4 mg, 1 hour before the GBCA administration, was administrated as premedication regimen. Recurrence rates of immediate HSR were compared according to prevention strategies.

RESULTS

A total of 185 patients with a history of mild immediate HSR to GBCA were re-exposed to GBCA 397 times during the study period. The overall recurrence rate was 19.6% (78/397). Changing the culprit GBCA significantly reduced the recurrence rate, compared with reusing the culprit GBCA (6.9%, 9/130 and 25.8%, 69/267; P < 0.001). The recurrence rate was lowest when the GBCA was changed to a different molecular structure class from the culprit agent, followed by changing to CM with the same molecular structure and reusing the culprit GBCA (6.2%, 7/113 vs 11.8%, 2/17 vs 25.8%, 69/267; P < 0.001 with χ test for trend). Single-dose premedication demonstrated no significant prophylactic effect on recurrence (20.4%, 17/98 vs 17.3%, 61/299 with and without premedication, respectively; P = 0.509). Premedication in addition to changing CM also showed no additional prophylactic effect (7.2%, 7/97 and 6.1%, 2/33, respectively; P = 0.821).

CONCLUSIONS

Changing the CM from the culprit agent could reduce the chance of HSR recurrence in patients with prior mild immediate HSR to GBCA, especially when the CM was changed to one of a different molecular structure class. However, single-dose premedication administration did not show significant HSR recurrence rate difference.

Pharmacologic and non-pharmacologic interventions to prevent hypersensitivity reactions of non-ionic iodinated contrast media: a systematic review protocol

INTRODUCTION

Iodinated contrast media are commonly used in medical imaging and can cause hypersensitivity reactions, including rare but severe life-threatening reactions. Although several prophylactic approaches have been proposed for severe reactions, their effects remain unclear. Therefore, we aim to review systematically the preventive effects of pharmacologic and non-pharmacologic interventions and predictors of acute, hypersensitivity reactions.

METHODS AND ANALYSIS

We will search the PubMed, EMBASE and Cochrane Central Register of Controlled Trials databases from 1 January 1990 through 31 December 2019 and will examine the bibliographies of eligible studies, pertinent review articles and clinical practice guidelines. We will include prospective and retrospective studies of any design that evaluated the effects of pharmacological and non-pharmacological preventive interventions for adverse reactions of non-ionic iodinated contrast media. Two assessors will independently extract the characteristics of the study and intervention and the quantitative results. Two independent reviewers will assess the risk of bias using standard design-specific validity assessment tools. The primary outcome will be reduction in acute contrast media-induced hypersensitivity reactions. The secondary outcomes will include characteristics associated with the development of contrast media-induced acute hypersensitivity reactions, and adverse events associated with specific preventive interventions. Unique premedication regimens (eg, dose, drug and duration) and non-pharmacological strategies will be analysed separately. Average-risk and high-risk patients will be considered separately. A meta-analysis will be performed if appropriate.

ETHICS AND DISSEMINATION

Ethics approval is not applicable, as this will be a secondary analysis of publicly available data. The results of the analysis will be submitted for publication in a peer reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42019134003.

Anaphylaxis-a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis

Anaphylaxis is an acute, potential life-threatening systemic allergic reaction that may have a wide range of clinical manifestations. Severe anaphylaxis and/or the need for repeated doses of epinephrine to treat anaphylaxis are risk factors for biphasic anaphylaxis. Antihistamines and/or glucocorticoids are not reliable interventions to prevent biphasic anaphylaxis, although evidence supports a role for antihistamine and/or glucocorticoid premedication in specific chemotherapy protocols and rush aeroallergen immunotherapy. Evidence is lacking to support the role of antihistamines and/or glucocorticoid routine premedication in patients receiving low- or iso-osmolar contrast material to prevent recurrent radiocontrast media anaphylaxis. Epinephrine is the first-line pharmacotherapy for uniphasic and/or biphasic anaphylaxis. After diagnosis and treatment of anaphylaxis, all patients should be kept under observation until symptoms have fully resolved. All patients with anaphylaxis should receive education on anaphylaxis and risk of recurrence, trigger avoidance, self-injectable epinephrine education, referral to an allergist, and be educated about thresholds for further care.

Drug hypersensitivity reactions in Asia: regional issues and challenges

There are geographical, regional, and ethnic differences in the phenotypes and endotypes of patients with drug hypersensitivity reactions (DHRs) in different parts of the world. In Asia, aspects of drug hypersensitivity of regional importance include IgE-mediated allergies and T-cell-mediated reactions, including severe cutaneous adverse reactions (SCARs), to beta-lactam antibiotics, antituberculous drugs, nonsteroidal anti-inflammatory drugs (NSAIDs) and radiocontrast agents. Delabeling of low-risk penicillin allergy using direct oral provocation tests without skin tests have been found to be useful where the drug plausibility of the index reaction is low. Genetic risk associations of relevance to Asia include human leucocyte antigen (HLA)-B*1502 with carbamazepine SCAR, and HLA-B*5801 with allopurinol SCAR in some Asian ethnic groups. There remains a lack of safe and accurate diagnostic tests for antituberculous drug allergy, other than relatively high-risk desensitization regimes to first-line antituberculous therapy. NSAID hypersensitivity is common among both adults and children in Asia, with regional differences in phenotype especially among adults. Low dose aspirin desensitization is an important therapeutic modality in individuals with cross-reactive NSAID hypersensitivity and coronary artery disease following percutaneous coronary intervention. Skin testing allows patients with radiocontrast media hypersensitivity to confirm the suspected agent and test for alternatives, especially when contrasted scans are needed for future monitoring of disease relapse or progression, especially cancers.

Recent developments and highlights in drug hypersensitivity

Drug hypersensitivity reactions (DHRs) are nowadays the third cause of allergy after rhinitis and asthma with a significant increase in prevalence in both adults and paediatric population with new drugs included as culprit. For this, DHRs represent not only a health problem but also a significant financial burden for affected individuals and health systems. Mislabelling DHRs is showing to be a relevant problem for both, false label of drug allergic and false label of nonallergic. All this reinforces the need to improve accurate diagnostic approaches that allow an appropriate management. Moreover, there is a need for training both, nonallergist stakeholders and patients to improve the reaction identification and therefore decrease the mislabelling. The use of allergy cards has shown to be relevant to avoid the induction of DHRs due to the prescription of wrong medication. Recent developments over the last 2 years and highlights about risk factors, diagnostic approaches, mechanisms involved as well as prevention actions, and management have been reviewed. In these papers, it has been outlined the need for correct diagnosis and de-labelling of patients previously false-reported as allergic, which will improve the management and treatment of patients with DHRs.

Relationship between Lower Dose and Injection Speed of Iodinated Contrast Material for CT and Acute Hypersensitivity Reactions: An Observational Study

BackgroundThere are few data on the relationship between acute hypersensitivity reactions and the dose and injection rate of iodinated contrast material for CT.PurposeTo determine the relationship between lower dose and injection speed of iodinated contrast material for CT and the rate of acute hypersensitivity reactions.Materials and MethodsThis retrospective study included adults (age ≥18 years) undergoing nonionic iodinated contrast material-enhanced abdominal CT between August 2016 and January 2017 (control period) and between August 2017 and January 2018 (intervention period); all examinations were conducted in an outpatient setting. Compared with CT during the control period, CT during the intervention period involved a reduced dose of contrast material achieved by lowering the CT tube voltage. CT examinations in the control period were performed with 120 kVp, a contrast material dose of 2 mL/kg (maximum, 150 mL), and an injection speed of 3 or 4 mL/sec. CT examinations in the intervention period were performed with 100 kVp, a contrast material dose of 1.5 mL/kg (maximum, 130 mL), and an injection speed of 2.5 or 3 mL/sec. Per-examination rates of acute hypersensitivity reactions to iodinated contrast material were compared between the control and intervention periods with use of a multivariable Poisson regression model, the parameters of which were estimated by using generalized estimating equations with an independence correlation structure.ResultsA total of 21947 adults (mean age ± standard deviation, 59 years ± 12; 8797 women [40%]) underwent 25119 CT examinations during the control period; 23019 adults (mean age, 59 years ± 12; 9538 women [41%]) underwent 26491 CT examinations during the intervention period. The rate of acute hypersensitivity reactions was 1.42% (376 of 26491 examinations; 95% confidence interval [CI]: 1.28%, 1.57%) in the intervention period and 1.86% (468 of 25119 examinations; 95% CI: 1.70%, 2.04%) in the control period, with a multivariable-adjusted relative risk of 0.85 (95% CI: 0.74, 0.99; P = .03).ConclusionReduction in the dose and injection speed of iodinated contrast material for CT was associated with a lower rate of acute hypersensitivity reactions to iodinated contrast material.© RSNA, 2019Online supplemental material is available for this article.