Classifying ADRs--does dose matter?

Interleukin (IL)-1/IL-6-Inhibitor-Associated Drug Reaction With Eosinophilia and Systemic Symptoms (DReSS) in Systemic Inflammatory Illnesses

BACKGROUND

After introducing IL-1/IL-6 inhibitors, some patients with Still and Still-like disease developed unusual, often fatal, pulmonary disease. This complication was associated with scoring as DReSS (drug reaction with eosinophilia and systemic symptoms) implicating these inhibitors, although DReSS can be difficult to recognize in the setting of systemic inflammatory disease.

OBJECTIVE

To facilitate recognition of IL-1/IL-6 inhibitor-DReSS in systemic inflammatory illnesses (Still/Still-like) by looking at timing and reaction-associated features. We evaluated outcomes of stopping or not stopping IL-1/IL-6 inhibitors after DReSS reaction began.

METHODS

In an international study collaborating primarily with pediatric specialists, we characterized features of 89 drug-reaction cases versus 773 drug-exposed controls and compared outcomes of 52 cases stopping IL-1/IL-6 inhibitors with 37 cases not stopping these drugs.

RESULTS

Before the reaction began, drug-reaction cases and controls were clinically comparable, except for younger disease-onset age for reaction cases with preexisting cardiothoracic comorbidities. After the reaction began, increased rates of pulmonary complications and macrophage activation syndrome differentiated drug-reaction cases from drug-tolerant controls (P = 4.7 × 10-35 and P = 1.1 × 10-24, respectively). The initial DReSS feature was typically reported 2 to 8 weeks after initiating IL-1/IL-6 inhibition. In drug-reaction cases stopping versus not stopping IL-1/IL-6-inhibitor treatment, reaction-related features were indistinguishable, including pulmonary complication rates (75% [39 of 52] vs 76% [28 of 37]). Those stopping subsequently required fewer medications for treatment of systemic inflammation, had decreased rates of macrophage activation syndrome, and improved survival (P = .005, multivariate regression). Resolution of pulmonary complications occurred in 67% (26 of 39) of drug-reaction cases who stopped and in none who continued inhibitors.

CONCLUSIONS

In systemic inflammatory illnesses, recognition of IL-1/IL-6-inhibitor-associated reactions followed by avoidance of IL-1/IL-6 inhibitors significantly improved outcomes.

Effectiveness of direct delabelling of allergy labels in type A adverse drug reactions to penicillin: a multicentre hospitalwide prospective cohort study

BACKGROUND

Patient-reported penicillin allergy labels (PALs) are associated with adverse patient outcomes and inappropriate antibiotic prescribing. Removal of PALs via direct oral challenge (DOC) is associated with increased penicillin utilization post removal.

OBJECTIVES

To assess the impact of direct delabelling (allergy label removal via medical reconciliation alone) of type A adverse drug reaction (ADR) PALs on inpatient prescribing.

METHODS

From January 2019 to December 2022 at two tertiary hospitals in Melbourne, patients aged ≥18 years with type A ADR PALs, as defined by the validated Antibiotic Allergy Assessment Tool, were offered direct delabelling or single-dose DOC. The primary endpoint was antibiotic use pre- and post-assessment (during index admission and 90 days post assessment). The secondary endpoint was the proportion of patients delabelled in the direct delabelling and DOC cohorts in the electronic medical record at 90 days post assessment.

RESULTS

Allergy labels (n = 4108) were assessed for 488 participants, with 490 individual type A ADR PAL assessments included. Three hundred and thirty-seven patients were directly delabelled, 69 underwent DOC and 84 were not delabelled. There was increased use of any penicillin following direct delabelling (OR 19.19, 95% CI 2.48-148.36) and DOC (OR 56.98, 95% CI 6.82-476.19) during the index admission, higher in the DOC group compared with direct delabelling (OR 2.97, 95% CI 1.39-6.37). Relabelling at 90 days was low with no statistically significant difference between direct delabelling (5/337; 1.5%) and DOC (0/69; 0%).

CONCLUSIONS

Both direct delabelling and DOC of type A ADR PALs increased penicillin usage; however, the impact was greatest with DOC. Most patients remain delabelled at 90 days.

How to manage drug-virus interplay underlying skin eruptions in children

The majority of viral rashes occurring during an antibiotic therapy are considered as a drug hypersensitivity reaction (DHR). Differentiating a viral rash versus a DHR is difficult or even impossible. In delayed DHRs the interplay between viruses and drugs is summarized according to the recent literature. The question is if the same reaction will again occur in case of drug re-exposure in absence of the concomitant viral infection because of persistent immune reactivity. Epstein Barr Virus (EBV) and Human Herpes virus 6 (HHV-6) models are analyzed in case of maculopapular exanthemas (MPEs) and drug reaction with eosinophilia and systemic symptoms (DRESS) over a course of drug therapy. MPEs are the most common skin manifestation during a viral infection and a concomitant drug therapy. In type IVb reactions to drugs a hapten/pro-hapten mechanism and a pharmacological interaction (p-i mechanism) are described as the 2 major ways to make T cells response functional. Rarely the altered repertoire model is involved. The Human Leukocyte Antigen (HLA) predisposition is an additional essential factor that can facilitate DHR. In MPEs rarely a DHR is confirmed by allergy testing. Severity and duration of MPEs, the presence of eosinophilia and systemic symptoms make more reliable the persistent nature of the reaction. Research on this topic is needed in order to provide the clinicians with instruments to decide when to suspect future reactions upon drug re-exposure even in the absence of a viral infection, because those patients should be investigated by a complete drug allergy work up.

Toxic Epidermal Necrolysis and Stevens - Johnson Syndrome Following Sintilimab Administration in a Non-Small Cell Lung Cancer Patient: A Case Report

Immune checkpoint inhibitors such as monoclonal antibodies have been used recently with greater effect for the management of non-small cell lung cancer (NSCLC). Sintilimab, a fully human IgG4 monoclonal antibody is specific for the immune checkpoint protein programmed cell death receptor-1 (PD-1). It is a common medication adopted for treating Hodgkin's lymphoma and NSCLC. The adverse effects associated with the use of monoclonal antibodies should be closely monitored and in the current report, the use of sintilimab for treating NSCLC led to skin-associated adverse effects such as Stevens-Johnson syndrome and toxic epidermal necrolysis. Genetic testing showed that genes such as KRAS, CREBBP, NTRK1, RAF1, and TP53 were mutated. Initial visible symptom included the formation of a vesicular rash on the skin that had spread to the upper limbs, chest, and dorsum 1 week after the administration of sintilimab. The patient received anti-inflammatory agents to prevent worsening of the rashes and further infections. When the vesicles in back and limbs enlarged and the neck skin began to desquamate, the patient was diagnosed with Stevens-Johnson syndrome and sintilimab-induced toxic epidermal necrolysis. Toxic epidermal necrolysis was diagnosed via clinical symptoms and physical examination. The patient also reported the symptoms of oral mucositis. As soon as the dose of sintilimab was reduced to 20 mg/day, the skin-associated condition of the patient began to improve. Although the lump in the lungs decreased considerably 45 days after initial administration of sintilimab, the medication was stopped from use as soon as the skin-related symptoms improved after its withdrawal. This report suggests that close monitoring, personal care, and proper use of medications such as sintilimab should be implemented to avoid such rare skin-associated toxicities as an adverse effect.

Tools for Etiologic Diagnosis of Drug-Induced Allergic Conditions

Drug hypersensitivity reactions are a serious concern in clinical practice because they can be severe and result in lifelong sequelae. An accurate diagnosis and identification of the culprit drug is essential to prevent future reactions as well as for the identification of safe treatment alternatives. Nonetheless, the diagnosis can be challenging. In vivo and in vitro tests can be helpful, although none are conclusive; therefore, the tests are not usually performed in isolation but as part of a diagnostic algorithm. In addition, some in vitro tests are only available in research laboratories, and standardization has not been fully accomplished. Collaborating research is needed to improve drug hypersensitivity reaction diagnosis. In this review, we update the current available in vivo and in vitro tools with their pros and cons and propose an algorithm to integrate them into clinical practice.

Pharmacometric modeling of drug adverse effects: an application of mixture models in schizophrenia spectrum disorder patients treated with clozapine

Clozapine has superior efficacy to other antipsychotics yet is underutilized due to its adverse effects, such as neutropenia, weight gain, and tachycardia. The current investigation aimed to introduce a pharmacometric approach to simultaneously model drug adverse effects, with examples from schizophrenia spectrum patients receiving clozapine. The adverse drug effects were represented as a function of time by incorporating a mixture model to describe individual susceptibility to the adverse effects. Applications of the proposed method were presented by analyzing retrospective data from patients' medical records in Psychiatric Clinic, Penang General Hospital. Tachycardia, weight gain, and absolute neutrophils count (ANC) decrease were best described by an offset, a piecewise linear, and a transient surge function, respectively. 42.9% of the patients had all the adverse effects, including weight gain (0.01 kg/m² increase every week over a baseline of 24.7 kg/m² until stabilizing at 279 weeks), ANC decrease (20% decrease from 4540 cells/µL week 12-20.8), and tachycardia (14% constant increase over a baseline of 87.9 bpm for a clozapine maintenance dose of 450 mg daily). 32.5% of the patients had only tachycardia, while the remaining 24.6% had none of the adverse effects. A new pharmacometric approach was proposed to describe adverse drug effects with examples of clozapine-induced weight gain, ANC drop, and tachycardia. The current approach described the longitudinal time changes of continuous data while assessing patient susceptibility. Furthermore, the model revealed the possible co-existence of ANC drop and weight gain; thus, neutrophil monitoring might predict future changes in body weight.

Population pharmacogenomics: an update on ethnogeographic differences and opportunities for precision public health

Both safety and efficacy of medical treatment can vary depending on the ethnogeographic background of the patient. One of the reasons underlying this variability is differences in pharmacogenetic polymorphisms in genes involved in drug disposition, as well as in drug targets. Knowledge and appreciation of these differences is thus essential to optimize population-stratified care. Here, we provide an extensive updated analysis of population pharmacogenomics in ten pharmacokinetic genes (CYP2D6, CYP2C19, DPYD, TPMT, NUDT15 and SLC22A1), drug targets (CFTR) and genes involved in drug hypersensitivity (HLA-A, HLA-B) or drug-induced acute hemolytic anemia (G6PD). Combined, polymorphisms in the analyzed genes affect the pharmacology, efficacy or safety of 141 different drugs and therapeutic regimens. The data reveal pronounced differences in the genetic landscape, complexity and variant frequencies between ethnogeographic groups. Reduced function alleles of CYP2D6, SLC22A1 and CFTR were most prevalent in individuals of European descent, whereas DPYD and TPMT deficiencies were most common in Sub-Saharan Africa. Oceanian populations showed the highest frequencies of CYP2C19 loss-of-function alleles while their inferred CYP2D6 activity was among the highest worldwide. Frequencies of HLA-B*15:02 and HLA-B*58:01 were highest across Asia, which has important implications for the risk of severe cutaneous adverse reactions upon treatment with carbamazepine and allopurinol. G6PD deficiencies were most frequent in Africa, the Middle East and Southeast Asia with pronounced differences in variant composition. These variability data provide an important resource to inform cost-effectiveness modeling and guide population-specific genotyping strategies with the goal of optimizing the implementation of precision public health.

Tackling the Patient with Multiple Drug "Allergies": Multiple Drug Intolerance Syndrome

As populations age, the prevalence of reported drug "allergy" increases, often leading to suboptimal care and increased morbidity because of unnecessary avoidance of safe and effective medications. Evaluation by a drug allergy specialist is often warranted when a patient has more than 2 unrelated drug "allergies" listed in the medical record. In this commentary, we clarify and propose standard terminology to use when evaluating patients with multiple drug allergy labels including and more specifically when diagnosing multiple drug intolerance syndrome and the much rarer multiple drug hypersensitivity syndrome. We review epidemiology and key features of multiple drug intolerance syndrome and multiple drug hypersensitivity syndrome. We summarize the methodologic and practical diagnostic workup and management of individuals with MDIS to assist with the accurate delabeling of drug "allergies" in the electronic health record.

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.

An Updated Review of the Diagnostic Methods in Delayed Drug Hypersensitivity

Delayed drug hypersensitivity reactions are clinically diverse reactions that vary from isolated benign skin conditions that remit quickly with no or symptomatic treatment, drug discontinuation or even continued drug treatment, to the other extreme of severe cutaneous adverse reactions (SCARs) that are associated with presumed life-long memory T-cell responses, significant acute and long-term morbidity and mortality. Diagnostic "in clinic" approaches to delayed hypersensitivity reactions have included patch testing (PT), delayed intradermal testing (IDT) and drug challenges for milder reactions. Patch and IDT are, in general, performed no sooner than 4-6 weeks after resolution of the acute reaction at the maximum non-irritating concentrations. Functional in vitro and ex vivo assays have largely remained the province of research laboratories and include lymphocyte transformation test (LTT) and cytokine release enzyme linked ImmunoSpot (ELISpot) assay, an emerging diagnostic tool which uses cytokine release, typically IFN-γ, after the patient's peripheral blood mononuclear cells are stimulated with the suspected drug(s). Genetic markers such as human leukocyte antigen have shown recent promise for both pre-prescription screening as well as pre-emptive and diagnostic testing strategies.

Global Frequencies of Clinically Important HLA Alleles and Their Implications For the Cost-Effectiveness of Preemptive Pharmacogenetic Testing

Immune-mediated drug hypersensitivity reactions are an important source of iatrogenic morbidity and mortality. Human leukocyte antigen (HLA)-B*57:01, HLA-B*15:02, HLA-A*31:01, and HLA-B*58:01 constitute established risk factors and preemptive genotyping of these HLA alleles in patients prior to the initiation of abacavir, carbamazepine, and allopurinol-based therapies can prevent toxicity and improve patient outcomes. However, the cost-effectiveness of preemptive HLA testing has only been evaluated in the United States and few countries in Europe and Asia. In this study, we consolidated HLA genotypes from 3.5-6.4 million individuals across up to 74 countries and modeled the country-specific cost-effectiveness of genetic testing. We find major ethnogeographic differences in risk allele prevalence, which translated into pronounced differences in the number of patients needed to test to prevent one case of severe hypersensitivity reactions between countries and populations. At incremental cost-effectiveness ratio thresholds of $40,000, testing of HLA-B*57:01 in patients initiating abacavir was cost-effective in the majority of countries with potential exceptions of East Asia, Saudi Arabia, Ghana, and Zimbabwe. For carbamazepine, preemptive genotyping of HLA-B*15:02 is only cost-effective across most of East and South Asia, whereas HLA-A*31:01 testing is likely to be cost-effective globally. Testing of HLA-B*58:01 is more likely to be cost-effective throughout Africa and Asia compared with Europe and the Americas. We anticipate that this data set can serve as an important resource for clinicians and health economists to guide clinical decision making and inform public healthcare strategies.

New Insights in Computational Methods for Pharmacovigilance: E-Synthesis, a Bayesian Framework for Causal Assessment

Today's surge of big data coming from multiple sources is raising the stakes that pharmacovigilance has to win, making evidence synthesis a more and more robust approach in the field. In this scenario, many scholars believe that new computational methods derived from data mining will effectively enhance the detection of early warning signals for adverse drug reactions, solving the gauntlets that post-marketing surveillance requires. This article highlights the need for a philosophical approach in order to fully realize a pharmacovigilance 2.0 revolution. A state of the art on evidence synthesis is presented, followed by the illustration of E-Synthesis, a Bayesian framework for causal assessment. Computational results regarding dose-response evidence are shown at the end of this article.

Pharmacogenomics in Papua New Guineans: unique profiles and implications for enhancing drug efficacy while improving drug safety

Papua New Guinea (PNG) can be roughly divided into highland, coastal and island peoples with significant mitochondrial DNA differentiation reflecting early and recent distinct migrations from Africa and East Asia, respectively. Infectious diseases such as tuberculosis, malaria and HIV severely impact on the health of its peoples for which drug therapy is the major treatment and pharmacogenetics has clinical relevance for many of these drugs. Although there is generally little information about known single nucleotide polymorphisms in the population, in some instances, their frequencies have been shown to be higher than anywhere worldwide. For example, CYP2B6*6 is over 50%, and CYP2C19*2 and *3 are over 40 and 25%, respectively. Conversely, CYP2A6*9, 2B6*2, *3, *4 and *18, and 2C8*3 appear to be much lower than in Whites. CYP2D6 known variants are unclear, and for phase II enzymes, only UGT2B7 and UGT1A9 data are available, with variant frequencies either slightly lower than or similar to Whites. Although almost all PNG people tested are rapid acetylators, but which variant(s) define this phenotype is not known. For HLA-B*13:01, HLA-B*35:05 and HLA-C*04:01, the frequencies show some regioselectivity, but the clinical implications with respect to adverse drug reactions are not known. There are minimal phenotype data for the CYPs and nothing is known about drug transporter or receptor genetics. Determination of genetic variants that are rare in Whites or Asians but common in PNG people is a topic of both scientific and clinical importance, and further research needs to be carried out. Optimizing the safety and efficacy of infectious disease drug therapy through pharmacogenetic studies that have translation potential is a priority.

Antibiotic allergy labels in hospitalized and critically ill adults: A review of current impacts of inaccurate labelling

Antibiotic allergy labels (AALs) are reported by approximately 20% of hospitalized patients, yet over 85% will be negative on formal allergy testing. Hospitalized patients with an AAL have inferior patient outcomes, increased colonization with multidrug-resistant organisms and frequently receive inappropriate antimicrobials. Hospitalized populations have been well studied but, to date, the impact of AALs on patients with critical illness remains less well defined. We review the prevalence and impact of AALs on hospitalized patients, including those in in critical care.

Genetic Basis of Delayed Hypersensitivity Reactions to Drugs in Jewish and Arab Populations

Genetic variation can affect drug pharmacokinetics and pharmacodynamics and contribute to variability between individuals in response to medications. Specifically, differences in allele frequencies among individuals and ethnic groups have been associated with variation in their propensity to develop drug hypersensitivity reactions (HSRs). This article reviews the current knowledge on the genetic background of HSRs and its relevance to Jewish and Arab populations. The focus is on human leukocyte antigen (HLA) alleles and haplotypes as predictive markers of HSRs ("immunopharmacogenetics"), but other genes and alleles are described as well. Also discussed is the translation of the pharmacogenetic information to practice recommendations.

Antibiotic Allergy in Pediatrics

The overlabeling of pediatric antibiotic allergy represents a huge burden in society. Given that up to 10% of the US population is labeled as penicillin allergic, it can be estimated that at least 5 million children in this country are labeled with penicillin allergy. We now understand that most of the cutaneous symptoms that are interpreted as drug allergy are likely viral induced or due to a drug-virus interaction, and they usually do not represent a long-lasting, drug-specific, adaptive immune response to the antibiotic that a child received. Because most antibiotic allergy labels acquired in childhood are carried into adulthood, the overlabeling of antibiotic allergy is a liability that leads to unnecessary long-term health care risks, costs, and antibiotic resistance. Fortunately, awareness of this growing burden is increasing and leading to more emphasis on antibiotic allergy delabeling strategies in the adult population. There is growing literature that is used to support the safe and efficacious use of tools such as skin testing and drug challenge to evaluate and manage children with antibiotic allergy labels. In addition, there is an increasing understanding of antibiotic reactivity within classes and side-chain reactions. In summary, a better overall understanding of the current tools available for the diagnosis and management of adverse drug reactions is likely to change how pediatric primary care providers evaluate and treat patients with such diagnoses and prevent the unnecessary avoidance of antibiotics, particularly penicillins.

The 3 Cs of Antibiotic Allergy-Classification, Cross-Reactivity, and Collaboration

Antibiotic allergy labeling is highly prevalent and negatively impacts patient outcomes and antibiotic appropriateness. Reducing the prevalence and burden of antibiotic allergies requires the engagement of key stakeholders such as allergists, immunologists, pharmacists, and infectious diseases physicians. To help address this burden of antibiotic allergy overlabeling, we review 3 key antibiotic allergy domains: (1) antibiotic allergy classification, (2) antibiotic cross-reactivity, and (3) multidisciplinary collaboration. We review the available evidence and research gaps of currently used adverse drug reaction classification systems, antibiotic allergy cross-reactivity, and current and future models of antibiotic allergy care.

Severe Delayed Cutaneous and Systemic Reactions to Drugs: A Global Perspective on the Science and Art of Current Practice

Most immune-mediated adverse drug reactions (IM-ADRs) involve the skin, and many have additional systemic features. Severe cutaneous adverse drug reactions (SCARs) are an uncommon, potentially life-threatening, and challenging subgroup of IM-ADRs with diverse clinical phenotypes, mechanisms, and offending drugs. T-cell-mediated immunopathology is central to these severe delayed reactions, but effector cells and cytokines differ by clinical phenotype. Strong HLA-gene associations have been elucidated for specific drug-SCAR IM-ADRs such as Stevens-Johnson syndrome/toxic epidermal necrolysis, although the mechanisms by which carriage of a specific HLA allele is necessary but not sufficient for the development of many IM-ADRs is still being defined. SCAR management is complicated by substantial short- and long-term morbidity/mortality and the potential need to treat ongoing comorbid disease with related medications. Multidisciplinary specialist teams at experienced units should care for patients. In the setting of SCAR, patient outcomes as well as preventive, diagnostic, treatment, and management approaches are often not generalizable, but rather context specific, driven by population HLA-genetics, the pharmacology and genetic risk factors of the implicated drug, severity of underlying comorbid disease necessitating ongoing treatments, and cost considerations. In this review, we update the basic and clinical science of SCAR diagnosis and management.

Pharmacogenomics of off-target adverse drug reactions

Off-target adverse drug reactions (ADRs) are associated with significant morbidity and costs to the healthcare system, and their occurrence is not predictable based on the known pharmacological action of the drug's therapeutic effect. Off-target ADRs may or may not be associated with immunological memory, although they can manifest with a variety of shared clinical features, including maculopapular exanthema, severe cutaneous adverse reactions (SCARs), angioedema, pruritus and bronchospasm. Discovery of specific genes associated with a particular ADR phenotype is a foundational component of clinical translation into screening programmes for their prevention. In this review, genetic associations of off-target drug-induced ADRs that have a clinical phenotype suggestive of an immunologically mediated process and their mechanisms are highlighted. A significant proportion of these reactions lack immunological memory and current data are informative for these ADRs with regard to disease pathophysiology, therapeutic targets and biomarkers which may identify patients at greatest risk. Although many serious delayed immune-mediated (IM)-ADRs show strong human leukocyte antigen associations, only a small subset have successfully been implemented in screening programmes. More recently, other factors, such as drug metabolism, have been shown to contribute to the risk of the IM-ADR. In the future, pharmacogenomic targets and an understanding of how they interact with drugs to cause ADRs will be applied to drug design and preclinical testing, and this will allow selection of optimal therapy to improve patient safety.

A web resource for mining HLA associations with adverse drug reactions: HLA-ADR

Human leukocyte antigens (HLA) are an important family of genes involved in the immune system. Their primary function is to allow the host immune system to be able to distinguish between self and non-self peptides—e.g. derived from invading pathogens. However, these genes have also been implicated in immune-mediated adverse drug reactions (ADRs), presenting a problem to patients, clinicians and pharmaceutical companies. We have previously developed the Allele Frequency Net Database (AFND) that captures the allelic and haplotype frequencies for these HLA genes across many healthy populations from around the world. Here, we report the development and release of the HLA-ADR database that captures data from publications where HLA alleles and haplotypes have been associated with ADRs (e.g. Stevens–Johnson Syndrome/toxic epidermal necrolysis and drug-induced liver injury). HLA-ADR was created by using data obtained through systematic review of the literature and semi-automated literature mining. The database also draws on data already present in AFND allowing users to compare and analyze allele frequencies in both ADR patients and healthy populations. The HLA-ADR database provides clinicians and researchers with a centralized resource from which to investigate immune-mediated ADRs.

Database URL: http://www.allelefrequencies.net/hla-adr/.

Antimicrobial allergy 'labels' drive inappropriate antimicrobial prescribing: lessons for stewardship

BACKGROUND

The presence of antimicrobial allergy designations ('labels') often substantially reduces prescribing options for affected patients, but the frequency, accuracy and impacts of such labels are unknown.

METHODS

The National Antimicrobial Prescribing Survey (NAPS) is an annual de-identified point prevalence audit of Australian inpatient antimicrobial prescribing using standardized definitions of guideline compliance, appropriateness and indications. Data were extracted for 2 years (2013-14) and compared for patients with an antimicrobial allergy label (AAL) and with no AAL (NAAL).

RESULTS

Among 21 031 patients receiving antimicrobials (33 421 prescriptions), an AAL was recorded in 18%, with inappropriate antimicrobial use significantly higher in the AAL group versus the NAAL group (OR 1.12, 95% CI 1.05-1.22, P < 0.002). Patterns of antimicrobial use were significantly influenced by AAL, with lower β-lactam use (AAL versus NAAL; OR 0.47, 95% CI 0.43-0.50, P < 0.001) and higher quinolone (OR 2.07, 95% CI 1.83-2.34, P < 0.0001), glycopeptide (OR 1.59, 95% CI 1.38-1.83, P < 0.0001) and carbapenem (OR 1.74, 95% CI 1.43-2.13, P < 0.0001) use. In particular, among immunocompromised patients, AAL was associated with increased rates of inappropriate antimicrobial use (OR 1.68, 95% CI 1.21-2.30, P = 0.003), as well as increased use of quinolones (OR 1.88, 95% CI 1.16-3.03, P = 0.02) and glycopeptides (OR 1.82, 95% CI 1.17-2.84, P = 0.01).

CONCLUSIONS

AALs are common and appear to be associated with higher rates of inappropriate prescribing and increased use of broad-spectrum antimicrobials. Improved accuracy in defining AALs is likely to be important for effective antimicrobial stewardship (AMS), with efforts to 'de-label' inappropriate AAL patients a worthwhile feature of future AMS initiatives.

The prevalence and impact of antimicrobial allergies and adverse drug reactions at an Australian tertiary centre

Background

The prevalence and impact of antimicrobial “allergy” labels and Adverse Drug Reactions (ADRs) on antibiotic usage and antimicrobial stewardship initiatives is ill defined. We sought to examine the rate of antimicrobial “allergy labels” at our tertiary referral centre and impacts on antimicrobial usage and appropriateness.

Methods

Two inpatient antimicrobial prevalence surveys were conducted over a 1-week period in November 2013 and 2014 as part of the prospective National Antimicrobial Prescribing Survey (NAPS). Post survey, patients recorded in the NAPS database were assigned to two groups based upon recorded antimicrobial “allergy label” and ADR: (i) Antimicrobial Allergy/ADR (AA) or (ii) No Antimicrobial Allergy/ADR (NAA). Antimicrobial usage and antimicrobial appropriateness were compared between AA and NAA groups.

Results

From 509 identified patients the prevalence of an antimicrobial allergy or ADR was 25 %. The prevalence of “allergy labels”/ADR was 10 % (51/509) for penicillin V/G, 5 % (24/509) cephalosporins, 4 % (22/509) trimethroprim-sulfamethoxazole and 3 % (17/509) aminopenicillins. One thousand and seventy antimicrobials were prescribed during the study periods, the median antimicrobial duration was longer in the AA versus NAA group (6 days vs. 4 days; p = 0.018), and proportion of inappropriate antimicrobial prescribing higher in the AA group compared with NAA (29 %; 35/120 vs. 23 %; 86/367, p = 0.22). Oral antimicrobial administration was higher in the NAA than AA group (60 %; 177/297 vs. 46 %; 356/793, p = 0.0001). The proportion of patients that received a β-lactam was lower in the AA versus NAA group (60 % vs. 79 %, p = 0.0001).

Conclusions

In an Australian tertiary referral centre an antimicrobial “allergy” or ADR label was found to significantly impacted on rate of oral antimicrobial administration, beta-lactam usage, antimicrobial duration and antimicrobial appropriateness.