Guideline for the diagnosis of drug hypersensitivity reactions: S2K-Guideline of the German Society for Allergology and Clinical Immunology (DGAKI) and the German Dermatological Society (DDG) in collaboration with the Association of German Allergologists (AeDA), the German Society for Pediatric Allergology and Environmental Medicine (GPA), the German Contact Dermatitis Research Group (DKG), the Swiss Society for Allergy and Immunology (SGAI), the Austrian Society for Allergology and Immunology (ÖGAI), the German Academy of Allergology and Environmental Medicine (DAAU), the German Center for Documentation of Severe Skin Reactions and the German Federal Institute for Drugs and Medical Products (BfArM)

Safety evaluation of a buffer used in the lyophilization of canine platelets: type I hypersensitivity reaction in dogs caused by bovine serum albumin

Introduction

The present study was designed to evaluate the safety of substances generally used in the preparation of lyophilized platelet products (LPPs) because the possibility of an immune response to bovine serum albumin (BSA) was considered high when using previously described technology.

Methods

An intradermal skin test, followed by a drug provocation test, was conducted to observe adverse events and identify the substances responsible for an immune response. Five male beagles (2 years old) weighing 12-14 kg were used. The dogs were clinically healthy and had no history of medication use. An intradermal skin test was conducted with each substance [i.e., 4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid, sodium chloride, potassium chloride, sodium bicarbonate, theophylline, trehalose, and BSA] used in the conventional freeze-dry method.

Results

In the intradermal skin test, three dogs tested positive at the BSA injection site and showed clinical signs after the intradermal injection, including nausea and vomiting. For the drug provocation test, all dogs received two intravenous injections of an LPP buffer solution. The initial injection was devoid of BSA, whereas the subsequent injection contained BSA. The three dogs that had reacted to BSA in the intradermal skin test exhibited adverse events such as lethargy, vomiting, and nausea immediately after intravenous injection of the LPP buffer containing BSA. All dogs recovered uneventfully after symptomatic treatment in both tests.

Discussion

The high incidence and severity of type I hypersensitivity reactions observed in this study suggested that BSA is unsuitable as a component of canine LPP.

Drug-induced hypersensitivity reactions in a Lebanese outpatient population: A decade-long retrospective analysis (2012-2021)

Background

Drug hypersensitivity reactions (DHRs) are becoming more common as a result of increasing prevalence and case complexity. Allergists and clinical immunologists worldwide are challenged daily to adequately diagnose and manage these reactions. Data in the literature regarding DHR outpatient consultations are scarce worldwide, limited in the Middle East, and currently unavailable in Lebanon.

Objective

This retrospective study aimed to evaluate the characteristics of all reported DHRs over 10 years in a tertiary-care allergy clinic in Lebanon.

Methods

We conducted a decade-long (2012-21) retrospective analysis of the archived medical records of patients with a history of DHRs. Demographics, clinical history, diagnostic tools, and characteristics of the DHRs were collected and analyzed.

Results

A total of 758 patients experienced DHRs to therapeutic molecules provided for ambulatory care. Our results identified 72 medications. The most frequently implicated drug classes included β-lactam antibiotics (53.8%), followed closely by nonsteroidal anti-inflammatory drugs (48.9%). Of the 758 patients, 32.6% reported DHRs to multiple molecules, and 11.8% reported concomitant DHRs to 1 or several molecules provided in the perioperative setting. Of those, opioids and neuromuscular blocking agents were the 2 most common therapeutic classes. Furthermore, we evaluated the cross-reactivity between molecules of the same class. In neuromuscular blocking agents, rocuronium and cisatracurium were the most commonly cross-reactive, and for opioids, the most common association we recorded was with morphine and pethidine.

Conclusion

Our findings constitute the first step toward a more comprehensive evaluation of the clinical characteristics of DHRs in Lebanon.

Evaluation of accompanying allergic disease in children with proven drug allergies

Background/aim

Data on the prevalence of allergic diseases in children with proven drug allergies are limited. We aim to evaluate the frequency of allergic comorbidity in children with proven common drug allergies.

Materials and methods

Children with drug hypersensitivity confirmed by diagnostic allergy tests at our center between January 2010 and December 2020 were screened retrospectively. Patients with the most common drug allergies (due to antibiotics, nonsteroidal antiinflammatory drugs [NSAIDs], and antiepileptic drugs) were selected for analysis. Age, sex, the culprit drug, initial reaction characteristics, diagnostic test results, and the study physician who diagnosed concomitant allergic diseases were noted.

Results

A total of 168 patients (boys, 51.2%) with a median age of 12 years (IQR = 8-16.3) were included in the study. The culprit drug was an antibiotic in 63% (n = 106), NSAID in 25% (n = 42) and anticonvulsant in 11.9 % (n = 20) of the patients. Drug hypersensitivity reactions were immediate in 74.4 % (n = 125) and delayed in 25.6 % (n = 43) of the patients. Seventy-five patients (44.6 %) had at least one allergic disease, most commonly rhinitis (27.3 %, n = 46) or asthma (25 %, n = 42). Fifty-five patients underwent skin prick tests with aeroallergens, producing a positive result in 60% (n = 31). The prevalence of allergic disease was not differing according to the culprit drug. The frequency of developing at least one concomitant allergic disease was 47.2% (n = 50/106) for antibiotic hypersensitivity, 52.4% (n = 22/42) for NSAID hypersensitivity, and 15% (n = 3/20) for anticonvulsant hypersensitivity (p < 0.00).Immediate drug hypersensitivity reactions were more frequent in children who had allergic diseases (80 % vs. 64.5 %; p = 0.027).

Conclusion

Nearly half (44.6%) of the children with proven drug hypersensitivity had concomitant allergic diseases and immediate reactions were more common in this group. Children evaluated for drug hypersensitivity should be assessed for other allergic diseases.

Guideline for allergological diagnosis of drug hypersensitivity reactions: S2k Guideline of the German Society for Allergology and Clinical Immunology (DGAKI) in cooperation with the German Dermatological Society (DDG), the Association of German Allergologists (ÄDA), the German Society for Pediatric Allergology (GPA), the German Contact Dermatitis Research Group (DKG), the German Society for Pneumology (DGP), the German Society of Otorhinolaryngology, Head and Neck Surgery, the Austrian Society of Allergology and Immunology (ÖGAI), the Austrian Society of Dermatology and Venereology (ÖGDV), the German Academy of Allergology and Environmental Medicine (DAAU), and the German Documentation Center for Severe Skin Reactions (dZh)

Not available.

[Diagnostics of drug allergies and intolerances]

The prevalence of hypersensitivity reactions to drugs is increasing. Currently, this affects more than 7% of the world population. Nonsteroidal anti-inflammatory drugs (NSAID) and beta-lactam antibiotics (BLA) are by far the most common pharmaceutical preparations involved in hypersensitivity reactions to drugs. Misdiagnoses are frequent and BLA allergies present a danger that can lead to adverse health outcomes. Therefore, delabeling (exclusion of a suspected diagnosis) is paramount for those affected. Following the occurrence of uncomplicated maculopapular exanthemas, outpatient oral drug provocation can be safely considered in children without prior skin tests. Immediate perioperative reactions are rare. The approach to studying these complex reactions requires collaboration between allergologists and anesthesiologists to provide the best possible care for these patients.

[Principles of allergy diagnostics]

BACKGROUND

Allergies are frequent and approximately 30% of the general population in Germany are affected. The specific sensitization against an allergen is asymptomatic. On renewed allergen contact the symptoms are indicative of the underlying pathomechanism. A variety of different test procedures are available to identify allergic reactions.

OBJECTIVE AND AIM

In this review article the typical clinical symptoms of allergic reactions are assigned to mechanisms and possible test methods are presented and discussed. Current developments in recombinant serum diagnostics and cellular testing methods are presented.

A multidisciplinary approach to verify and de-label of drug allergic histories in a university hospital in Thailand: a retrospective descriptive study

BACKGROUND

Mislabeling of drug allergic histories causes avoidable negative impacts on patients and healthcare system. Although multidisciplinary adverse drug reaction (ADR) services to verify and de-label drug allergic histories have been operated in particular hospitals in Thailand, their performances have not been reported. This research aimed to examine the effectiveness of verification of drug allergic history and de-labeling (VD) services of the physician-led multidisciplinary ADR clinic.

METHODS

This research was a retrospective descriptive study. Medical charts of patients with at least one drug allergic history who received VD services at the multidisciplinary clinic between January 2017 to December 2018, were reviewed. Data on the history of drug allergy, VD services, and results were analyzed and presented using descriptive statistics.

RESULTS

Seventy patients' charts were reviewed, and 171 unconfirmed drug allergic histories were identified. 79.53% of the reported reactions involved skin and soft tissues. The most found adverse skin reactions were maculopapular rash, pruritic and erythematous rash, and angioedema. The remaining 20.47% were systemic reactions which included drug reaction with eosinophilia and systemic symptoms (DRESS), anaphylaxis, and nausea/vomiting was the most prevalent. Antituberculosis, beta-lactam antibiotics, and nonsteroidal anti-inflammatory drugs (NSAIDs) were the most reported suspected drugs. Drug allergic history reviewing by physicians or pharmacists could confirm and de-label for 3 and 20 reactions, respectively. Seven and one reactions were confirmed by enzyme-linked immunospot assay and patch test, respectively. The provocation tests with the suspected or alternative drug were conducted in 64 reactions. Twelve reactions were confirmed, and 45 reactions were de-labeled. Totally, 65/171 (38.01%) allergic histories were successfully de-labeled, 23/171 (13.45%) were confirmed, and 83/171 (48.53%) were inconclusive.

CONCLUSIONS

More than half of drug allergic histories were successfully confirmed or de-labeled by the multidisciplinary ADR team. The collaborative activities of various healthcare professionals, consisting of physicians, nurse, and pharmacists as presented in the study were effective in VD services and should be implemented in other healthcare settings.

Outcomes of a Undiluted, One-Bag Desensitization Protocol for Chemotherapeutic Agents

BACKGROUND

Hypersensitive reactions (HSRs) often require that the provoking medication be discontinued but chemotherapeutic drugs are often essential for the treatment of the disease. Rapid drug desensitization is a procedure that induces temporary tolerance to the drug allowing continuation of treatment in patients who have presented HSRs. Most of the desensitization protocols use 3 bags with sequential dilutions of the drug, which are infused in gradual steps. However, it has not been sufficiently investigated whether dilution is essential for successful desensitization.

OBJECTIVE

The objective of this study was to evaluate the efficacy and safety of a new one-bag desensitization protocol which uses a single solution of 1 mg/mL throughout the procedure allowing to reduce time and simplifying the desensitization procedure.

METHODS

Retrospective observational study was carried out in adult patients with HSRs to chemotherapy agents who received a new nondilution one-bag desensitization protocol between 2016 and 2021.

RESULTS

A total of 130 desensitization procedures with an undiluted one-bag protocol were performed on 17 patients with HSRs to chemotherapy. One hundred and seven (82.3%) were for desensitization to CBDCA, 15 (11.5%) for oxaliplatin, 4 (3.1%) for paclitaxel and 4 (3.1%) for brentuximab. All of the 130 procedures were successfully accomplished, and all patients could receive their target dose. No breakthrough reactions (BTRs) occurred in 77% (100/130) of desensitizations, and only mild reactions (grade 1) with skin symptoms were observed in 23% (30/130) of desensitizations.

CONCLUSION AND RELEVANCE

The undiluted one-bag desensitization protocol was safe and effective and has been adopted as the standard of care at our institution in treating patients with HSRs to chemotherapeutic drugs as it requires less time and simplifies the desensitization procedure, optimizing risk management.

Characterization of immunologically detectable T-cell sensitization, Immunohistochemical detection of pro-inflammatory cytokines, and clinical parameters of patients after allogeneic intraoral bone grafting procedures: a prospective randomized controlled clinical trial in humans

BACKGROUND

The null hypotheses were tested that intraoral bone augmentation using two different allogeneic materials has no impact on the patient's blood levels of material-specific lymphocytes and on the immunohistochemical detection of pro-inflammatory cytokines IL-1α, IL1ß and TNF-α and T-cell markers CD4, CD8 in biopsies of the test groups.

METHODS

In this prospective RCT, 60 systemically healthy participants were randomly assigned to two allogeneic test groups (1: Maxgraft®, freeze-dried, multiple donors, and 2: Puros®, solvent-dehydrated, single donor) and an autologous control group (10 patients). Plasma samples were collected pre-(T1) and postoperatively (2 weeks (T2) and 4 months (T3)). The Lymphocyte Transformation Test (LTT) was used for analyzing levels of transformed lymphocytes for type IV immune reactions by 3H-thymidine activity. Bone biopsies were harvested at T3 and immunohistochemically analyzed for IL-1α, IL1ß, TNF-α, CD4, CD8 and correlated with the immunological and clinical findings.

RESULTS

A statistically significant difference between the tested materials was observed for LTT measurements at T3 (p = 0.033). Furthermore, three groups were identified: Group A (LTT negative T1-T3, n = 48), group B (LTT positive T1-T3, n = 7), group C (developing positive LTT at T2, n = 5). A highly significant elevation of IL-1α, IL1ß, TNF-α in patients of group C (p = 0.0001) and a significant elevation of CD4+ cells in patients of group B (p = 0.005) was shown.

CONCLUSION

Our data show that following allogeneic bone grafting, local and systemic immunological reactions can be detected in some patients. These findings were statistically significant for the timepoint T3 between the tested materials as well as for the groups B and C correlated with group A for both tested materials. Therefore, the null hypotheses were rejected. A preoperative compatibility test for allogeneic materials in order to improve patient safety and the predictability of these materials would be desirable.

TRIAL REGISTRATION

Ethical commission of the Ärztekammer Hamburg, Germany (PV5211) as well as by the German Registry of Clinical Studies (DRKS00013010) on 30/07/2018 ( http://apps.who.int/trialsearch/ ).

Lymphocyte Transformation Test for drug allergy detection: when does it work?

BACKGROUND

The lymphocyte transformation test (LTT) is an in vitro test system for the detection of a sensitization in the context of allergies to drugs. Its reported sensitivity varies largely and seems to be affected by different parameters. In review articles, the average LTT performance was often calculated by combining overall mean sensitivities of various published studies, but without considering different patient characteristics or varying patient numbers per publication.

OBJECTIVE

This meta-analysis aims to investigate the impact of different patient-specific and methodical parameters on the sensitivity of the LTT based on data on the level of the individual patient extracted from single studies.

METHODS

We performed an advanced literature search in Pubmed and screened the identified publications according to previously defined inclusion criteria. In total, individual patient data from 721 patients were extracted from 30 studies. Random-effects meta-regression analyses were performed.

RESULTS

The analysis indicate that the ELISA-based read-out is more sensitive compared to the classical radioactivity method (ELISA: 80% vs. radioactivity: 66%;p=0.084). Interestingly, DRESS/DHISS is associated with a higher probability of a positive LTT test result compared to other investigated clinical phenotypes ("DRESS/DHISS" vs. "bullous reaction"; OR: 2.52;p-value=0.003). Our analysis also revealed an impact of the time to testing period after the occurrence of the allergic event ("<2 weeks" vs. "2 weeks-2 months"; OR: 2.12;p-value=0.034).

CONCLUSION

The read-out method and relevant clinical parameters affect the sensitivity of the LTT. These findings are based on a meta-analysis providing a higher level of evidence than a single study or previous reviews not considering individual patient data.

Immediate Hypersensitivity Reactions Induced by COVID-19 Vaccines: Current Trends, Potential Mechanisms and Prevention Strategies

As the world deals with the COVID-19 pandemic, vaccination remains vital to successfully end this crisis. However, COVID-19-vaccine-induced immediate hypersensitivity reactions presenting with potentially life-threatening systemic anaphylactic reactions are one of the reasons for vaccine hesitancy. Recent studies have suggested that different mechanisms, including IgE-mediated and non-IgE-mediated mast cell activation, may be involved in immediate hypersensitivity. The main culprits triggering hypersensitivity reactions have been suggested to be the excipients of vaccines, including polyethylene glycol and polysorbate 80. Patients with a history of allergic reactions to drugs, foods, or other vaccines may have an increased risk of hypersensitivity reactions to COVID-19 vaccines. Various strategies have been suggested to prevent hypersensitivity reactions, including performing skin tests or in vitro tests before vaccination, administering different vaccines for the primary and following boosters, changing the fractionated doses, or pretreating the anti-IgE antibody. This review discusses the current trends, potential mechanisms, and prevention strategies for COVID-19-vaccine-induced immediate hypersensitivity reactions.

Psychiatric comorbidity and quality of life in patients with drug hypersensitivity

Background: Compared with advances in a drug hypersensitivity diagnosis and management, little is known about the mental health status of patients with drug hypersensitivity and the impact of this psychological distress on their quality of life (QoL). Objective: The objectives were to evaluate anxiety, depression, and QoL levels in patients with drug hypersensitivity, assess how some related factors may affect them, and determine the impact of disease on their QoL. Methods: A total of 203 patients with drug hypersensitivity and 80 healthy controls were evaluated with the Beck Anxiety (BAI) and the Depression Inventory (BDI), and the short version of the World Health Organization Quality of Life (WHOQOL-BREF) scale. Results: The mean ± standard deviation (SD) BAI scores of the patients and the controls were 13.46 ± 11.78 and 1.94 ± 1.93, respectively (p < 0.0001). The mean ± SD BDI scores were higher in the patient group (9.23 ± 6.36) than in the control group (2.18 ± 2.02) (p < 0.0001). The patients had significantly increased risk of anxiety versus the controls (48.8% versus 7.5%) (odds ratio [OR] 11.74 [95% confidence {CI}, 4.88-28.20]; p < 0.0001) and depression versus the controls (31.5% versus 6.2%) (OR 6.90 [95% CI, 2.66-17.90]; p = 0.0001). The comparison of patients' BAI and BDI scores showed that those with more severe reactions had higher scores than those with moderate and mild reactions. A negative correlation was found among all WHOQOL-BREF scale domain scores and the BAI and BDI scores. Conclusion: Anxiety and depressive symptoms have a high prevalence in patients with confirmed drug hypersensitivity, which leads to a notable decrease in QoL. Self-administered psychological questionnaires were shown to be useful in the psychological examination and management of patients with drug hypersensitivity. Therefore, we found that psychological support is critical to reducing the negative outcomes of hypersensitivity reactions in patients.

Safety of Cefazolin Test Dose in Patients with Penicillin Allergy Just Prior Cardiac Device Implantation: A Single Center Experience

Background

Cephalosporins are the cornerstone of cardiac device infection prophylaxis. Owing to fears of cross-reactivity, penicillin-allergic patients are exposed to potentially more-toxic drugs, with decreased efficacy. We evaluated the safety of a cefazolin test dose (CTD) in self-reported penicillin-allergic patients.

Methods

In this single-centre study, we evaluated consecutive patients with chart documentation of penicillin allergy undergoing cardiac device implantation, over a 2-year period. A CTD was performed if no cephalosporin allergy or severe anaphylactic reaction to penicillin had been documented. Patients were given 2 doses of 100 mg IV cefazolin, and if no allergic reaction occurred after 5 minutes, the full dose (1800 mg) was administered in the electrophysiology laboratory just before the implantation procedure.

Results

A total of 2200 patients were included. The frequency of reported penicillin allergy was 9.3% (n = 204). In 80% of cases, the type of allergic reaction was not reported in medical notes or was unknown by the patient. A CTD was performed in 67.6% of patients with a penicillin allergy (n = 138). A total of 5 adverse events occurred (3.6% of patients [95% confidence interval, 1.1%-6.1%]) — 4 skin rashes and 1 tongue edema. These 5 patients became asymptomatic after antihistaminic and corticosteroid IV treatment. Even if the test dose was negative, 79% of patients also were administered vancomycin before the procedure, as it requires a 1-hour infusion prior to the CTD in the implantation procedure room.

Conclusion

A CTD in most penicillin-allergic patients appears to be safe and allows its use per recommended guidelines.

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.

Methods for Identifying Culprit Drugs in Cutaneous Drug Eruptions: A Scoping Review

BACKGROUND

Cutaneous drug eruptions are a significant source of morbidity, mortality, and cost to the healthcare system. Identifying the culprit drug is essential; however, despite numerous methods being published, there are no consensus guidelines.

OBJECTIVES

Conduct a scoping review to identify all published methods of culprit drug identification for cutaneous drug eruptions, compare the methods, and generate hypotheses for future causality assessment studies.

ELIGIBILITY CRITERIA

Peer-reviewed publications involving culprit drug identification methods.

SOURCES OF EVIDENCE

Medline, Embase, and Cochrane Central Register of Controlled Trials.

CHARTING METHODS

Registered PRISMA-ScR format protocol on Open Science Forum.

RESULTS

In total, 109 studies and 26 reviews were included comprising 656,635 adverse drug events, most of which were cutaneous. There were 54 methods of culprit drug identification published, categorized as algorithms, probabilistic approaches, and expert judgment. Algorithms had higher sensitivity and positive predictive value, but lower specificity and negative predictive value. Probabilistic approaches had lower sensitivity and positive predictive value, but higher specificity and negative predictive value. Expert judgment was subjective, less reproducible, but the most frequently used to validate other methods. Studies suggest that greater accuracy may be achieved by specifically assessing cutaneous drug eruptions and using combinations of causality assessment categories.

CONCLUSIONS

Culprit drug identification for adverse drug reactions remains a challenge. Many methods have been published, but there are no consensus guidelines. Using causality assessment methods specifically for cutaneous drug eruptions and combining aspects of the different causality assessment categories may improve efficacy. Further studies are needed to validate this hypothesis.

Preparations of exploration of immediate hypersensitivity to antineoplastic agents: An oncology pharmacy perspective

BACKGROUND

Cancer patients are being exposed to antineoplastic drugs more frequently and for longer periods, resulting in a higher risk of hypersensitivity reactions. The aim of this study was to assess the pharmaceutical time and direct cost of drug allergy explorations following immediate hypersensitivity reactions to antineoplastic agents.

METHODS

A micro-costing method was used to collect data on consumption of human and material resources for allergy exploration preparations. The monetisation was carried out on the basis of prices and hourly wage costs applied in 2018. The number and type of allergy explorations prepared by the pharmacy as well as nature of antineoplastic drugs tested, and the number of culprit drugs reintroductions were collected.

RESULTS

Almost 1.5 h is required to realise allergy tests for one patient including pharmacist time for prescription analysis and pharmacy technician's time for tests preparation. The mean manufacturing cost of these tests is estimated at €62.87 (€57.82-65.49) per culprit drug for one patient. Programming patients according to culprit drugs tested allows rationalising healthcare provider time and increasing efficiency. From January 2010 to December 2018, 277 patients were tested and 490 allergy explorations were performed, corresponding to more than 5000 preparations. Mostly, the culprit drug could be reintroduced (n = 383, 78.2%) allowing patients to receive the best possible treatment.

CONCLUSION

Management of hypersensitivity reactions is constantly progressing, as it contributes to improving patient care in oncology. This activity is time-consuming for the pharmacy team but allows patients with previous hypersensitivity reaction to continue effective treatment.

Management of Trichomoniasis in the Setting of 5-Nitroimidazole Hypersensitivity

ABSTRACT

Metronidazole and other 5-nitroimidazoles are the mainstay of Trichomonas vaginalis treatment, with few efficacious and safe treatment options available outside of this class. Patients with trichomoniasis and a history of a clinically confirmed hypersensitivity reaction to 5-nitroimidazoles present a management challenge for clinicians. The first step in managing such patients is metronidazole desensitization. In situations where this cannot be performed or tolerated, treatment with alternative regimens outside of the 5-nitroimidazole class, such as intravaginal boric acid or paromomycin, may be possible.

Is There an Increased Risk of Hepatotoxicity with Metamizole? A Comparative Cohort Study in Incident Users

INTRODUCTION

The analgesic metamizole, which has been withdrawn from the market in several countries due to the risk of agranulocytosis but is still available on the market in Germany and some other countries, has been associated with liver injury in published case reports; however, epidemiological studies on the risk of liver injury are limited.

OBJECTIVE

The aim of this study was to compare the risk of liver injury up to 270 days after the first start of treatment with metamizole with the corresponding risk in patients starting treatment with paracetamol, using a retrospective cohort incident user design.

METHODS

The first prescription for either metamizole or paracetamol in the Intercontinental Medical Statistics (IMS)^® Disease Analyzer Germany database during the study period (2009-2018) was identified in patients with at least 365 days of observation and no prior diagnosis of liver events, cancer or HIV, or treatment within the last 6 months with hepatotoxic drugs typically administered for chronic conditions. Each patient was followed for specific liver events for 90 days after the prescription. In case of a new prescription within 90 days, a new 90-day observation period started, up to a maximum of 270 days. Cox regression was used to compare the risk of liver injury in the two groups.

RESULTS

Metamizole was associated with a higher risk of liver injury compared with paracetamol (adjusted hazard ratio 1.69, 95% confidence interval 1.46-1.97). Sensitivity analyses were performed to evaluate the robustness of these findings. In all the sensitivity analyses, metamizole was still associated with a higher risk of liver injury, including an analysis where naproxen was used as a comparator instead of paracetamol.

CONCLUSIONS

Results from this study support previous studies suggesting that metamizole is associated with a significant risk of liver injury. Nevertheless, a possible impact of residual confounding cannot be excluded.

Detection of drug-specific immunoglobulin E (IgE) and acute mediator release for the diagnosis of immediate drug hypersensitivity reactions

The diagnosis of a drug hypersensitivity reaction (DHR) is complex. The first step after taking the clinical history is to look for a sensitization to confirm or exclude the diagnosis and to identify the culprit drug. Skin tests are the primary means of detecting sensitization in DHR, but are associated with a risk for a severe reaction and may be contraindicated. In vitro tests offer the potential to support or confirm a diagnosis of DHR and influence medical decision making. For immediate-type DHR, a few validated assays for measurement of specific IgE (sIgE) are commercially available to a limited number of drugs. In addition, several home-made sIgE radioimmunoassays have been used in other studies. The sensitivity of the sIgE assay is drug-dependant and generally low (0-85%) for betalactams and reported heterogeneous for other drugs ranging from 26% for chlorhexidine and 44% for suxamethonium to 92% for chlorhexidine. However, as all these studies included patients, in whom DHR was confirmed only by skin tests and not by provocation, the results have to be interpreted carefully and may be unreliable. Determination of mediators during an acute phase of a reaction may indirectly support the diagnosis of a DHR by demonstrating mast cell and basophil mediator release. Negative in vitro tests do not exclude a DHR or imputability of a drug, but a positive result may support causality and eliminate the necessity for a drug provocation test. Unfortunately, evidence is limited with a lack of well-controlled studies in larger numbers of well-phenotyped patients, which results in susceptibility for bias and a need for future multicenter studies.

Update on Type-1 Allergy Diagnostics

Diagnostics in type-1 allergy rely on medical history and clinical examination. Extent and severity of signs and symptoms can be documented by standardized scores and questionnaires. Both skin prick test and intradermal test are useful for search of immunoglobulin E-mediated sensitizations but the availability of commercially available diagnostic extracts has been markedly reduced during the last years. Investigation of total and of specific serum IgE is the most important in vitro diagnostic analyte in type-1 allergy. Identification of the individual molecules to which patients are sensitized, known as molecular or component-resolved diagnostics (CRD), has recently markedly improved management of type-1 allergy to pollen, food and hymenoptera venoms. Main features of CRD are increased analytic sensitivity, detection of cross-reactivity and determination of individual sensitization profiles which allow for risk assessment and facilitate decisions for or against allergen immunotherapy. Basophil activation test as well as determination of selected biomarkers (e.g. tryptase) may also be helpful in some cases. If any allergy test is positive, one will have to distinguish reactions, which are clinically relevant, from those, which are not. In vivo provocation tests (e.g. nasal provocation, oral drug or food challenge) may help to clarify the relevance of a sensitization.

Future perspectives on in-vitro diagnosis of drug allergy by the lymphocyte transformation test

This article aims to envisage future perspectives of the lymphocyte transformation test (LTT). We describe the select innovative techniques, which can be integrated at different stages of the LTT to potentially improve the sensitivity, specificity, or practicability of the LTT. We first focus upon the cell sorting techniques comprising immunomagnetic cell separation and flow cytometry, which can be implemented prior and after the LTT culturing step to concentrate and quantify specific immune cell types. Further, we elaborate upon three important omics techniques such as transcriptomics, proteomics, and metabolomics, which can be integrated downstream of the LTT to analyze molecular changes in specific immune cells following drug induced activation and proliferation. We also develop visions, how state of the art techniques used in other scientific fields, can be transferred and applied in the context of in-vitro detection of drug allergy.

Praktischer Umgang mit allergischen Reaktionen auf COVID-19-Impfstoffe

Hintergrund: Zur vorbeugenden Behandlung von COVID-19 (Coronaviruserkrankung 2019) wurden in einer beispiellosen weltweiten Forschungsanstrengung Sicherheit und Wirksamkeit neuer Impfstoffplattformen studiert, die noch nie zuvor am Menschen eingesetzt wurden. Weniger als ein Jahr nach der Entdeckung der SARS-CoV-2-Virussequenz (SARS-CoV-2, "severe acute respiratory syndrome coronavirus type 2") wurden diese in zahlreichen Ländern für den Einsatz zugelassen und es wurde mit Massenimpfungen begonnen. Die bislang in der Europäischen Union (EU) zugelassenen mRNA-Impfstoffe (mRNA, "messenger"-RNA) gegen SARS-CoV-2 BNT162b2 und mRNA-1273 basieren auf einer ähnlichen lipidbasierten Nanopartikelträgertechnologie; die Lipidkomponenten unterscheiden sich jedoch. Schwere allergische Reaktionen und Anaphylaxien nach COVID-19-Impfungen sind sehr seltene unerwünschte Nebenwirkungen, die aber aufgrund potenziell letaler Ausgänge viel Aufmerksamkeit erhalten und ein hohes Maß an Verunsicherung ausgelöst haben.

Methoden: Das aktuelle Wissen zu anaphylaktischen Reaktionen auf Impfstoffe und speziell zu den derzeit neuen mRNA-COVID-19-Impfstoffen wurde zusammengestellt mittels einer Literaturanalyse durch Recherchen in Medline, Pubmed sowie den nationalen und internationalen Studien- und Leitlinienregistern, der Cochrane Library und dem Internet unter besonderer Berücksichtigung offizieller Webseiten der World Health Oranization (WHO), der Centers for Disease Control and Prevention (CDC), der European Medicines Agency (EMA), des Robert-Koch-Instituts (RKI) und des Paul-Ehrlich-Instituts (PEI).

Ergebnisse: Basierend auf der internationalen Literatur und bisheriger Erfahrungen zu schweren allergischen Reaktionen im Kontext der COVID-19-Impfungen werden von einem Expertengremium Empfehlungen für Prophylaxe, Diagnostik und Therapie dieser allergischen Reaktionen gegeben.

Schlussfolgerung: Vor einer COVID-19-Impfung mit den derzeit zugelassenen Impfstoffen sind Allergietests für die allermeisten Allergiker nicht notwendig. Bei allergischer/anaphylaktischer Reaktion auf den verabreichten COVID-19-Impfstoff wird eine allergologische Abklärung empfohlen, wie auch für eine kleine potenzielle Risikopopulation vor der ersten Impfung. Die Evaluierung und Zulassung von Testverfahren sollten hierfür erfolgen.

Zitierweise: Klimek L, Bergmann K-C, Brehler R, Pfützner W, Zuberbier T, Hartmann K, Jakob T, Novak N, Ring J, Merk H; Hamelmann E, Ankermann T, Schmidt S, Untersmayr E, Hötzenecker W, Jensen-Jarolim E, Brockow K, Mahler V, Worm M. Practical Handling of Allergic Reactions to COVID-19 vaccines. A Position Paper from German and Austrian Allergy Societies AeDA, DGAKI, GPA and ÖGAI. Allergo J Int 2021;30:79-95

https://doi.org/10.1007/s40629-021-00165-7

Model Based Evaluation of Hypersensitivity Adverse Drug Reactions to Antimicrobial Agents in Children

Drug use in children is-in most cases-supported by extrapolation of data generated from clinical trials in adult populations. This puts children at higher risk of developing adverse drug reactions (ADRs) due to "off-label" use of drugs and dosing issues. Major types of ADRs are drug hypersensitivity reactions, an idiosyncratic type of ADRs that are largely unpredictable and can cause high morbidity and mortality in a hard-to-identify specific population of patients. Lack of a complete understanding of the pathophysiology of DHRs and their unpredictive nature make them problematic in clinical practice and in drug development. In addition, ethical and legal obstacles hinder conducting large clinical trials in children, which in turn make children a "therapeutic orphan" where clear clinical guidelines are lacking, and practice is based largely on the personal experience of the clinician, hence making modeling desirable. This brief review summarizes the current knowledge of model-based evaluation of diagnosis and management of drug hypersensitivity reactions (DHRs) to antimicrobial drugs in the pediatric population. Ethical and legal aspects of drug research in children and the effect of different stages of child development and other factors on the risk of DHRs are discussed. The role of animal models, in vitro models and oral provocation test in management of DHRs are examined in the context of the current understanding of the pathophysiology of DHRs. Finally, recent changes in drug development legislations have been put forward to encourage drug developers to conduct trials in children clearly indicate the urgent need for evidence to support drug safety in children and for modeling to guide these clinical trials.

Practical handling of allergic reactions to COVID-19 vaccines: A position paper from German and Austrian Allergy Societies AeDA, DGAKI, GPA and ÖGAI

BACKGROUND

For the preventive treatment of the 2019 coronavirus disease (COVID-19) an unprecedented global research effort studied the safety and efficacy of new vaccine platforms that have not been previously used in humans. Less than one year after the discovery of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral sequence, these vaccines were approved for use in the European Union (EU) as well as in numerous other countries and mass vaccination efforts began. The so far in the EU approved mRNA vaccines BNT162b2 and mRNA-1273 are based on similar lipid-based nanoparticle carrier technologies; however, the lipid components differ. Severe allergic reactions and anaphylaxis after COVID-19 vaccination are very rare adverse events but have drawn attention due to potentially lethal outcomes and have triggered a high degree of uncertainty.

METHODS

Current knowledge on anaphylactic reactions to vaccines and specifically the new mRNA COVID-19 vaccines was compiled using a literature search in Medline, PubMed, as well as the national and international study and guideline registries, the Cochrane Library, and the Internet, with special reference to official websites of the World Health Organization (WHO), US Centers for Disease Control and Prevention (CDC), Robert Koch Institute (RKI), and Paul Ehrlich Institute (PEI).

RESULTS

Based on the international literature and previous experience, recommendations for prophylaxis, diagnosis and therapy of these allergic reactions are given by a panel of experts.

CONCLUSION

Allergy testing is not necessary for the vast majority of allergic patients prior to COVID-19 vaccination with currently licensed vaccines. In case of allergic/anaphylactic reactions after vaccination, allergy workup is recommended, as it is for a small potential risk population prior to the first vaccination. Evaluation and approval of diagnostic tests should be done for this purpose.

In-Vitro Approaches to Predict and Study T-Cell Mediated Hypersensitivity to Drugs

Mitigating the risk of drug hypersensitivity reactions is an important facet of a given pharmaceutical, with poor performance in this area of safety often leading to warnings, restrictions and withdrawals. In the last 50 years, efforts to diagnose, manage, and circumvent these obscure, iatrogenic diseases have resulted in the development of assays at all stages of a drugs lifespan. Indeed, this begins with intelligent lead compound selection/design to minimize the existence of deleterious chemical reactivity through exclusion of ominous structural moieties. Preclinical studies then investigate how compounds interact with biological systems, with emphasis placed on modeling immunological/toxicological liabilities. During clinical use, competent and accurate diagnoses are sought to effectively manage patients with such ailments, and pharmacovigilance datasets can be used for stratification of patient populations in order to optimise safety profiles. Herein, an overview of some of the in-vitro approaches to predict intrinsic immunogenicity of drugs and diagnose culprit drugs in allergic patients after exposure is detailed, with current perspectives and opportunities provided.

Drug-specific history, skin and in vitro tests can reduce the need for drug provocation tests in betalactam-hypersensitivity

BACKGROUND

Many patients report questionable drug hypersensitivity reactions (DHR) to betalactam antibiotics. A workup is required for objectivation. Direct drug provocation tests (DPTs) omitting a prior allergy workup are increasingly recommended as the primary diagnostic approach. However, apart from the risk of severe side effects, DPTs often are a scarce resource in overloaded healthcare-systems. We investigated how many cases can be solved by drug-specific history, drug-specific IgE, and skin tests obviating the need for DPT.

METHODS

We conducted a chart review in a retrospective cohort of 932 patients in an allergy outpatient centre from 2016 to 2017. Patients had been submitted to drug-specific history and specific IgE-, skin prick-, intradermal- and patch-tests with early and late readings with a series of penicillins and cephalosporins but DPTs were no option.

RESULTS

Overall, positive in vitro and/or skin tests were found in 96/932 (10.3%) patients. Drug-specific IgE was detected in 40/932 (4.3%) patients, 61/787 (7.8%) patients had positive skin tests. In vitro tests to Pencillin V showed the highest rate of positivity 24/479 (5.0%) and early readings of ampicillin the highest amongst the skin tests (3/49, 6.1%). Immediate skin tests were more often positive than delayed ones (75:45). The combination of all parameters including drug-specific history solved 346/932 (37.1%) cases while 586/932 (62.9%) remained unresolved. Self-reported DHR could be less often confirmed in females and young children (p < 0.05).

CONCLUSIONS

Testing with betalactams applying simple, cheap, and safe skin and blood tests can solve a third of DHR-cases on a high throughput scale.

Lymphocyte transformation test: History and current approaches

Drug-induced hypersensitivity reactions encompass a variety of different clinical phenotypes ranging from harmless rashes to fatal reactions. They can be classified into allergic (i.e. drug allergy) and non-allergic reactions (i.e. non-allergic hypersensitivity). Drug allergies in turn can either be antibody (e.g. IgE) or T cell-mediated. One of the diagnostic tools for the in vitro detection of drug allergy is the lymphocyte transformation test (LTT) which is based on the activation and expansion of the drug-specific memory T cells following co-incubation of the patient's peripheral mononuclear cells (PMBC) with the suspected drug in vitro. The read-out parameter in the classical LTT is T cell proliferation which can be measured as counts per minute following the addition of radiolabeled thymidine to the cell culture. However, in the course of time different modifications of the classical LTT with regard to the read-out parameters and methods have been proposed. Likewise, variations of the LTT platform itself have been described in the literature. This review article describes the development of the classical LTT and its use in the context of drug allergy detection and summarizes the modifications which have been published over time.

Induction of penicillin tolerance during pregnancy: Allergological opinion on the recommendation of the current AWMF Guidelines on Diagnosis and Treatment of Syphilis (AWMF Registry No. 059-002)

Not available.

Does delayed urticaria induced by drug allergy exist?

With the help of a routine clinical case about delayed urticaria induced by drug, we have analyzed the scientific societies reports published during the last 5 years on this topic. We highlighted the differences between the EAACI consensus and documents on drug allergy, commenting their positions and some of their definitions on delayed urticaria. However, the question of disagreement between definitions of delayed urticaria can generate confusion. It would be beneficial to have more and "official" clearness about this topic because of its important clinical application to our patients.

Hypersensitivity reactions to non-steroidal anti-inflammatory drugs (NSAIDs) - a retrospective study

BACKGROUND

The aim of this study was to verify the validity of clinical history and oral provocation challenges of patients with NSAID hypersensitivity and to identify safe alternatives. The COX-2 inhibitor etoricoxib, in particular, was studied.

PATIENTS AND METHODS

In all, 104 patients with confirmed diagnoses of NSAID hypersensitivity treated at the Department of Dermatology, Frankfurt University Hospital, Germany between 2004 and 2012 were retrospectively studied.

RESULTS

The medical history and hypersensitivity symptoms during oral provocation testing (OPT) largely coincided and were mostly mild to moderate. Acetylsalicylic acid (ASA) was the most frequent trigger both anamnestically (27.9 %) and during OPT (47.8 %). Etoricoxib caused the fewest reactions during OPT (4.2 %). Acetaminophen led to reactions in only 6.7 % of the cases studied although it was named more often in clinical histories (14 %).

CONCLUSIONS

OPT should be the aim whenever possible as most symptoms are mild to moderate. To distinguish between selective and cross-hypersensitivity reactions, ASA should be part of the test protocol. Furthermore, the findings of this study indicate that etoricoxib and acetaminophen are safe treatment alternatives in case of NSAID hypersensitivity. However, these drugs should not be administered without prior OPT in an inpatient setting, as severe symptoms can occur.

Suspected penicillin allergy: risk assessment using an algorithm as an antibiotic stewardship project

Background

Beta-lactam antibiotics (BLA) are the treatment of choice for a large number of bacterial infections. Putative BLA allergies are often reported by patients, but rarely confirmed. Many patients do not receive BLA due to suspected allergy. There is no systematic approach to risk stratification in the case of a history of suspected BLA allergy.

Methods

Using the available stratification programs and taking current guidelines into account, an algorithm for risk stratification, including recommendations on the use of antibiotics in cases of compellingly indicated BLA despite suspected BLA allergy, was formulated by the authors for their maximum care university hospital.

Results

The hospital is in great need of recommendations on how to deal with BLA allergies. Patient-reported information in the history forms the basis for classifying the reactions into four risk categories: (1) BLA allergy excluded, (2) benign delayed reaction, (3) immediate reaction, and (4) severe cutaneous and extracutaneous drug reaction. Recommendations strictly depend on this classification and range from use of full-dose BLA or use of BLA under certain conditions (e.g., two-stage dose escalation, non-cross-reactive BLA only) to prohibiting all BLA and the use of alternative non-BLA. In case of suspected immediate or delayed allergic reactions, there is an additional recommendation regarding subsequent allergy testing during a symptom-free interval.

Conclusion

Triage of patients with suspected BLA is urgently required. While allergy testing, including provocation testing, represents the most reliable solution, this is not feasible in all patients due to the high prevalence of BLA allergies. The risk stratification algorithm developed for the authors’ hospital represents a tool suitable to making a contribution to rational antibiotic therapy.

S3 guidelines: Epicutaneous patch testing with contact allergens and drugs - Short version, Part 1

Epicutaneous patch testing is the diagnostic standard for the detection of allergic contact dermatitis. The present guidelines are aimed at residents and board-certified physicians in the fields of dermatology and allergology as well as other medical specialties involved in establishing the indication for patch testing and its execution in patients with contact dermatitis and other forms of delayed-type hypersensitivity. The target audience also includes other health care providers and insurance funds. Based on a systematic literature search and a formal consensus process (S3), the guidelines were developed by dermatologists in collaboration with pediatricians, occupational medicine physicians, nursing staff as well as patient representatives. The systematic methodological approach and appraisal of evidence upon which the recommendations are based are outlined in a separate method report that also contains evidence tables. The guidelines address general aspects of patch testing as well as medicolegal issues. The recommendations given relate to topics such as the indication for patch testing, informed patient consent, as well as the choice of test substances, test chambers and test site, duration of exposure, reading times and interpretation of test reactions. Furthermore, recommendations are provided with respect to endogenous and exogenous factors, specific patient groups (children, pregnant women, immunosuppressed individuals) as well as possible risks and adverse events associated with patch testing using contact allergens. Note: This publication is part 1 of the short version of the S3 guidelines for "Epicutaneous patch testing using contact allergens and drugs" (registry no. 013 - 018; date: March 20, 2019; valid until December 31, 2021). Part 2 of the short version will be published in the next issue. The long version of these guidelines can be accessed at www.awmf.org. The method report is available as online publication (https://www.awmf.org/leitlinien/detail/ll/013-018.html) and contains the evidence tables in its appendix.

Eosinophil/Neutrophil/Platelet-to-Lymphocyte Ratios in Various Types of Immediate Hypersensitivity to NSAIDs: A Preliminary Study

BACKGROUND

The eosinophil/neutrophil/platelet-to-lymphocyte ratios (ELR, NLR, and PLR) have been used as clinical markers of systemic inflammation. However, they have not yet been tested in various subtypes of immediate hypersensitivity to nonsteroidal anti-inflammatory drugs (NSAIDs).

OBJECTIVES

To assess the ELR, NLR, and PLR in various types of hypersensitivity to NSAIDs.

MATERIALS AND METHODS

A retrospective analysis of complete blood cell count and the ELR, NLR, and PLR was performed. Appropriate types of hypersensitivity to NSAIDs were diagnosed based on the anamnesis and drug provocation tests. The analysis covered 97 patients. Twenty were diagnosed with NERD (NSAID-exacerbated respiratory disease), 20 with NECD (NSAID-exacerbated cutaneous disease), 38 with NIUA (NSAID-inducted urticaria/angioedema), and 19 with SNIUAA (single-NSAID-induced urticaria/angioedema or anaphylaxis). Two controls groups were included: the first covered 15 patients with bronchial asthma and the second 28 patients with chronic spontaneous urticaria without NSAID hypersensitivity.

RESULTS

The NLR did not differ significantly between the NSAID hypersensitivity types. The ELR was significantly higher in NERD patients, and the PLR was significantly lower in NECD patients than in patients with other types of NSAID hypersensitivity and in controls.

CONCLUSIONS

The ELR and PLR may be useful in differentiating various types of immediate hypersensitivity to NSAIDs. Moreover, the ELR may be helpful in differentiating patients with bronchial asthma with and without NSAID hypersensitivity and PLR in differentiating patients with chronic spontaneous urticaria from NECD.

Azathioprine Hypersensitivity Syndrome during Treatment of Severe Interstitial Lung Disease with Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis

Azathioprine is used to treat anti-neutrophil cytoplasmic antibody- (ANCA-) associated vasculitis. Azathioprine hypersensitivity syndrome is often missed. An 81-year-old man undergoing treatment for interstitial pneumonia developed a high fever and was diagnosed with ANCA-associated vasculitis based on an elevated myeloperoxidase- (MPO-) ANCA titer and renal biopsy findings. After induction therapy, his clinical symptoms improved, but his MPO-ANCA remained elevated (>300 U·L⁻¹) and hematuria persisted. Prednisolone plus azathioprine was administered as maintenance therapy. Three exacerbations of the inflammatory response occurred during the subsequent 3 months. In each instance, we suspected opportunistic infection or a flare-up of vasculitis. The first exacerbation was treated with an increased prednisolone dose and antibiotics. At the onset of the second exacerbation, which was accompanied by systemic erythema, we stopped azathioprine and administered antibiotics. The third exacerbation, which occurred the day after restarting azathioprine, involved a fever with chills and an acute inflammatory reaction; we therefore suspected an azathioprine allergy. A drug provocation test was performed, and a hyperinflammatory response was observed. The patient received prednisolone (15 mg·day⁻¹) monotherapy; no further fever was observed during the subsequent 2 months. We therefore diagnosed azathioprine hypersensitivity syndrome. Under treatment with prednisolone (5 mg·day⁻¹) and mycophenolate mofetil (1 g·day⁻¹) (replacing the azathioprine), no signs of relapse or infection have occurred for more than two years. Renal function and the pulmonary lesions are stable, although the high MPO-ANCA titer and hematuria persist. The diagnosis of azathioprine hypersensitivity is often delayed because of the difficulty in identifying the relationship between immunosuppressive agents and hypersensitivity and in distinguishing this from infection or relapse of the primary disease. The misdiagnosis of azathioprine hypersensitivity leads to unnecessary treatment; thus, clinicians should consider allergic reactions specific to azathioprine when switching from induction to maintenance therapy.

Role of in vivo and in vitro Tests in the Diagnosis of Severe Cutaneous Adverse Reactions (SCAR) to Drug

Severe cutaneous adverse reactions (SCAR) are life-threatening conditions including acute generalized exanthematous pustulosis (AGEP), Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN) and drug reaction with eosinophilia and systemic symptoms (DRESS). Diagnosis of causative underlying drug hypersensitivity (DH) is mandatory due to the high morbidity and mortality upon re-exposure with the incriminated drug. If an underlying DH is suspected, in vivo test, including patch tests (PTs), delayed-reading intradermal tests (IDTs) and in vitro tests can be performed in selected patients for which the suspected culprit drug is mandatory, or in order to find a safe alternative treatment. Positivity of in vivo and in vitro tests in SCAR to drug varies depending on the type of reaction and the incriminated drugs. Due to the severe nature of these reactions, drug provocation test (DPT) is highly contraindicated in patients who experienced SCAR. Thus, sensitivity is based on positive test results in patients with a suggestive clinical history. Patch tests still remain the first-line diagnostic tests in the majority of patients with SCAR, followed, in case of negative results, by delayed-reading IDTs, with the exception of patients with bullous diseases where IDTs are still contra-indicated. In vitro tests have shown promising results in the diagnosis of SCAR to drug. Positivity is particularly high when the lymphocyte transformation test (LTT) is combined with cytokines and cytotoxic markers measurement (cyto-LTT), but this still has to be confirmed with larger studies. Due to the rarity of SCAR, large multi-center collaborative studies are needed to better study the sensitivity and specificity of in vivo and in vitro tests.

β-Lactam allergy testing and delabeling-Experiences and lessons from Singapore

Background

β‐Lactam allergy is over‐reported and this leads to greater healthcare costs. Allergy testing has inherent risks, yet patients who test negative may continue avoiding β‐lactams.

Objective

To evaluate the safety and diagnostic value of β‐lactams allergy testing locally and usage of antibiotics following negative testing.

Methods

We performed a retrospective medical record review and follow‐up survey of patients who underwent β‐lactam testing between 2010 and 2016 at the National Skin Centre, Singapore.

Results

We reviewed the records of 166 patients, with a total of 173 β‐lactam allergy labels. Eighty (46.2%) labels were to penicillin, 75 (43.1%) to amoxicillin/amoxicillin‐clavulanic acid, 11 (6.4%) to cephalexin, and 5 (2.9%) to others. Skin tests were performed in 142 patients and drug provocation tests (DPTs) in 141 patients. Eleven (6.6%) patients defaulted DPTs after skin testing. Out of 166 patients, 22 (13.3%) patients were proven allergic by either skin tests (16) or DPTs (6). Patients who tested positive had nonsevere reactions.

Out of 155 patients who were conclusively evaluated, 133 (85.8%) were not allergic. Of these patients, 30 (22.6%) used the tested β‐lactam subsequently, with one reporting a mild reaction. Fifty‐one (38.3%) patients were uncontactable or uncertain if they consumed a β‐lactam since testing negative. Fifty‐two (39.1%) patients had no re‐exposure (35 had no indication, 17 were fearful of reactions).

Conclusion

Drug allergy testing was safe and removed inappropriate labels.

Clinical Implication

Allergy testing is efficacious, but fears of subsequent rechallenge should be addressed to maximize the effectiveness of allergy delabeling.