Single-step direct drug provocation testing is safe for delabelling selected non-low-risk penicillin allergy labels

Challenging dogmas: Intravenous versus oral beta-lactam antibiotic provocation tests

Background

Drug provocation tests (DPT) are considered the gold standard procedure to ascertain the diagnosis of beta-lactam (BL) allergy. Regarding route of administration, current recommendations prioritize oral challenges, considering them safer, and reserving the intravenous route for drugs for which this is the only formulation.

Objective

To compare in terms of tolerance and safety two protocols of BL DPT, using an oral protocol (OR-DPT) and an intravenous protocol (IV-DPT).

Methods

A descriptive, retrospective study was performed, including adult patients who underwent IV-DPT or OR-DPT for suspected immediate or delayed hypersensitivity to BL antibiotics, over a period of 4 years (between January 2018 and December 2021). Demographical data, index hypersensivity reactions' characteristics and tolerance to DPT were reviewed.

Results

A total of 1036 patients underwent DPT, mean age of 56.8 (standard deviation, SD, 17.8) years, 655 were women (63.2%). Immediate drug hypersensitivity reactions (DHR) had occurred in 564 of patients (54.4%). OR-DPT were performed in 439 (42.4%) and IV-DPT in 597 (57.6%). The frequency of reactions during DPT, regardless of the route used, was low (3.6%): only 16 (3.6%) in OR-DPT and 21 (3.5%) in IV-DPT. From IV-DPT, 16 out 21 DHR during DPT were immediate compared with 4 out of 16 in OR-DPT. Adjusted relative risk of developing a hypersensitivity reaction during IV-DPT versus OR-DPT was 1.13 (95% confidence interval (CI)0.57-2.22).

Conclusion

The results suggest that OR-DPT and IV-DPT are both safe procedures when adequately performed. However, IV-DPT protocols showed a higher rate of immediate DHR during DPT probably due to the selection of basal high-risk patients to undergo IV-DPT. In conclusion, IV-DPT may be considered as an option for challenges in drug-allergy studies, entailing a precise administration.

EAACI/ENDA position paper on drug provocation testing

In drug hypersensitivity, drug provocation testing (DPT), also called drug challenge, is the gold standard for investigation. In recent years, risk stratification has become an important tool for adjusting the diagnostic strategy to the perceived risk, whilst still maintaining a high level of safety for the patient. Skin tests are recommended before DPT but may be omitted in low-risk patients. The task force suggests a strict definition of such low-risk patients in children and adults. Based on experience and evidence from studies of allergy to beta-lactam antibiotics, an algorithm on how to adjust DPT to the risk, and when to omit skin tests before DPT, is presented. For other antibiotics, non-steroidal anti-inflammatory drugs and other drugs, skin tests are poorly validated and DPT is frequently necessary. We recommend performing DPT with chemotherapeutics and biologicals to avoid unnecessary desensitization procedures and DPT with skin tests negative contrast media. We suggest DPT with anesthetics only in highly specialized centers. Specifics of DPT to proton pump inhibitors, anticonvulsants and corticosteroids are discussed. This position paper provides general recommendations and guidance on optimizing use of DPT, whilst balancing benefits with patient safety and optimizing the use of the limited available resources.

Is a Prolonged Drug Provocation Test Better Than a Single-Day Drug Provocation Test? A Systematic Review and Meta-Analysis

BACKGROUND

There is currently no standardized duration of drug provocation test (DPT) for confirming/delabeling beta-lactam hypersensitivity reaction (BL-HSR).

OBJECTIVES

This meta-analysis and systematic review aimed to investigate the added diagnostic value of extended-day over single-day DPT for confirming/delabeling BL-HSR in adults and children.

METHODS

The MEDLINE, EMBASE, Web of Science, and CINAHL online databases were searched from inception to March 15, 2023, for studies that performed extended-day DPT to confirm/delabel BL-HSR. Risk difference and risk ratio were used to compare the proportions of patients with confirmed BL-HSR by single-day or extended-day DPT.

RESULTS

A total of 10,371 DPTs from 42 studies were included. Extended-day DPTs ranged from 2 to 7 days, or as long as index reactions were reported (maximum 10 days). The overall prevalence of confirmed BL-HSR was 6.96% (3.31% during the first-day DPT, and 3.65% during extended-day DPT). Approximately half of the positive reactions during extended-day DPT occurred during the second/third day. The increased detected pool prevalence of confirmed BL-HSR yielded by extended-day DPT was 0.03 (95% CI, 0.02%-0.04%; I2 = 57.69%; P < .001), and the risk ratio of positive reactions between extended-day and single-day DPT was 1.94 (95% CI, 1.62-2.33; I2 = 36.26%; P < .001). The risk difference increased per 1% increase in prevalence of BL-HSR by 0.6% (95% CI, 0.4%-0.7%; P < .001). Twenty-three severe reactions occurred during DPT, and only 2 severe reactions (0.02%) occurred during extended-day DPT. An additional 28 extended-day DPTs were needed to identify 1 mild reaction.

CONCLUSIONS

The increased prevalence of confirmed BL-HSR observed during extended-day DPT could be attributed to the first-day DPT. As a result, our findings do not conclusively support the use of extended-day DPT over single-day DPT. Further studies, incorporating a washout period, are required to comprehensively compare these 2 approaches.

Safety of Direct Drug Provocation for the Evaluation of Penicillin Allergy in Low-Risk Adults

BACKGROUND

About 10% of patients have a penicillin allergy label, but less than 5% of them are actually allergic. Unnecessary penicillin avoidance is associated with serious medical consequences. Given the growing number of these labels, it is imperative that our diagnostic strategy for penicillin allergy be as efficient as possible. The validity of traditionally used skin tests (STs) has been questioned, whereas drug provocation testing (DPT), the criterion standard, without previous ST appears very safe in most cases.

OBJECTIVE

To evaluate the safety of direct DPT without consideration for ST results and the validity of ST in the diagnosis of penicillin allergy.

METHODS

In this prospective cohort study without a control group, we recruited patients consulting an allergist for penicillin allergy. Patients underwent ST followed by DPT regardless of ST results. Patients with anaphylaxis to penicillin within the past 5 years or a severe delayed reaction were excluded, as were those with significant cardiorespiratory comorbidity.

RESULTS

None of the 1002 recruited patients had a serious reaction to DPT. Ten (1.0%) had a mild immediate reaction, of whom only 1 (0.1%) was considered likely IgE-mediated. The positive and negative predictive values of ST for an immediate reaction were 3.6% and 99.1%, respectively.

CONCLUSIONS

In a low-risk adult population reporting penicillin allergy, ST has very poor positive predictive value. Direct DPT without ST is safe and appears to be an ideal diagnostic strategy to remove penicillin allergy labels that could be implemented in first-line practice.

Low-risk penicillin allergy delabeling: a scoping review of direct oral challenge practice, implementation, and multi-disciplinary approaches

INTRODUCTION

Penicillin allergy is common, and there is increased clinician interest in direct oral challenge (DOC) as a testing strategy for low-risk penicillin allergy. To aid wider implementation of DOC, consensus definitions of low-risk penicillin allergy phenotypes, and standardized approaches to assessment, DOC procedures, and evaluation, are required.

AREAS COVERED

This review systematically reviews studies that have utilized penicillin DOC in healthcare settings to identify heterogeneity in implementation approaches and synthesize low-risk definitions, procedures, and evaluation.

EXPERT OPINION

Opportunity exists to standardize penicillin DOC procedures in patients with a low-risk penicillin allergy to optimize antimicrobial prescribing and reduce the burden of penicillin allergy. Standardizing the definitions of 'low-risk' and 'positive challenge,' and improving the evaluation of patient safety, alongside the development of a unified approach to the structure of undertaking an oral challenge, is likely to increase uptake and confidence among non-allergist clinicians.

The Burden of Self-Reported Antibiotic Allergies in Health Care and How to Address It: A Systematic Review of the Evidence

BACKGROUND

Antibiotics are the first-line treatment for bacterial infections; however, overuse and inappropriate prescribing have made antibiotics less effective with increased antimicrobial resistance. Unconfirmed reported antibiotic allergy labels create a significant barrier to optimal antimicrobial stewardship in health care, with clinical and economic implications.

OBJECTIVE

A systematic review was conducted to summarize the impact of patient-reported antibiotic allergy on clinical outcomes and various strategies that have been employed to effectively assess and remove these allergy labels, improving patient care.

METHODS

The review was undertaken using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A critical appraisal was conducted on all studies and a narrative synthesis was performed to identify themes.

RESULTS

Four themes emerged: the prevalence of antibiotic allergy, impact of antibiotic allergy on antimicrobial prescribing, impact of antibiotic allergy on clinical outcomes, and delabeling strategies to improve clinical outcomes. Of the 32 studies, including 1,089,675 participants, the prevalence of reported antibiotic allergy was between 5% and 35%. Patients with a reported antibiotic allergy had poorer concordance with prescribing guidelines in 30% to 60% of cases, with a higher use of alternatives such as quinolone, tetracycline, macrolide, lincosamide, and carbapenem and lower use of beta-lactam antibiotics. Antibiotic allergy delabeling was identified as an intervention and recommendation to advance the state of the science.

CONCLUSIONS

There is substantial evidence within the literature that antibiotic allergy labels significantly impact patient clinical outcomes and a consensus that systematic assessment of reported antibiotic allergies, commonly referred to as delabeling, improves the clinical management of patients.

Follow-up of penicillin allergy labels 1 year after successful penicillin delabeling

BACKGROUND

Penicillin allergy delabeling confers many benefits, including reduced patient morbidity and mortality and improved health economics. Reports suggest that both patients and clinicians often remain hesitant to take and prescribe penicillins, respectively, after penicillin delabeling. However, follow-up of an individual's penicillin allergy label and incorporation of this into relevant health care records after delabeling have not been well studied in the Australian population.

OBJECTIVE

To evaluate the status of penicillin allergy labels in the community 1 year after penicillin delabeling at a tertiary hospital in Australia.

METHODS

A cross-sectional study was performed using follow-up interviews with patients and community primary care providers after 1 year from the date of patients' penicillin delabeling at a tertiary hospital in New South Wales, Australia. The main outcome measures that were evaluated included patient willingness to accept penicillin for future infections, patient self-reported receipt of penicillin-based antibiotics after delabeling, accuracy of penicillin allergy labels in the records of the primary care provider, and prescription of penicillin-based antibiotics by the general practitioner.

RESULTS

A total of 86 patients were included in this study. The percentage of patients with a correct penicillin allergy status at 1-year follow-up was 94% in the hospital electronic medical record but only 37% in primary care records. At 1-year follow-up, 14% of delabeled patients continued to reject penicillin prescriptions.

CONCLUSION

Better strategies are required to increase patient confidence in receiving penicillins after penicillin delabeling and to ensure that penicillin allergy labels are translated into the medical records at the primary care level.

Tools to improve the diagnosis and management of T-cell mediated adverse drug reactions

Delayed drug T-cell immune-mediated hypersensitivity reactions have a large clinical heterogeneity varying from mild maculopapular exanthema (MPE) to severe cutaneous adverse reactions (SCARs) such as acute generalized exanthematous pustulosis (AGEP), drug reaction with eosinophilia and systemic symptoms (DRESS) and severe skin necrosis and blistering as seen in Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Given the knowledge gaps related to the immunopathogenesis of these conditions, the absence of validated diagnostic tools and the significant associated morbidity and mortality, patients with SCARs often have limited drug choices. We performed a comprehensive review aiming to evaluate in vivo diagnostic tools such as delayed intradermal skin and patch testing and ex vivo/in vitro research assays such as the lymphocyte transformation test (LTT) and the enzyme-linked ImmunoSpot (ELISpot) assay. We searched through PubMed using the terms “drug allergy,” “in vivo” and “ex vivo” for original papers in the last 10 years. A detailed meticulous approach adapted to the various clinical phenotypes is recommended for the diagnostic and management of delayed drug hypersensitivity reactions. This review highlights the current diagnostic tools for the delayed drug hypersensitivity phenotypes.

Quality Improvement to Engage General Pediatrics in Reducing Inaccurate Penicillin Allergy Labels

OBJECTIVE

To remove inaccurate penicillin allergy labels in the general pediatric clinic setting.

METHODS

From October 2017 through December 2021, this collaborative, quality improvement project used education, feedback, electronic health record alerts, and the introduction of oral amoxicillin challenges in a general pediatric clinic setting with the primary aim of decreasing the proportion of penicillin allergy labeled patients. Control charts were used to track the relationship between interventions and improvements in referral rates to allergy clinic, removal of the allergy label at clinic visits and the overall proportion of clinic patients labeled as PCN allergic.

RESULTS

Referral rates to allergy clinic for penicillin allergy labeled patients increased from a baseline mean of 1.9% to 20.4%. The proportion of PCN allergy labeled patients who had the label removed during a pediatric clinic visit increased from a baseline of 1.1% to 6.6%. The overall proportion of penicillin allergy labeled clinic patients decreased from a baseline of 3.4% to 2.2%.

CONCLUSION

With adequate education and collaboration with allergists, general pediatric practitioners can play a significant role in removing inaccurate penicillin allergy labels. Pediatricians can remove some of the burden placed on allergists by evaluating low risk patients in the primary care setting while referring higher risk patients to the specialist.

Economic Viability of Penicillin Allergy Testing to Avoid Improper Clindamycin Surgical Prophylaxis

OBJECTIVE

Patients mislabeled with a penicillin allergy are often unnecessarily given prophylactic clindamycin. Thus, otolaryngologists may cause harm due to clindamycin's associated risk of Clostridioides difficile infections (CDI) and surgical site infections (SSI). The objective of this study was to determine the economic feasibility of penicillin allergy testing in preventing unnecessary clindamycin use among patients with an unconfirmed penicillin allergy prior to otolaryngologic surgery.

METHODS

A break-even analysis was performed using the average cost of penicillin allergy testing and a CDI/SSI to calculate the absolute risk reduction (ARR) in baseline CDI/SSI rate due to clindamycin required for penicillin testing to be economically sustainable. The binomial distribution was used to calculate the probability that current penicillin testing can achieve this study's ARR.

RESULTS

Preoperative penicillin testing was found to be economically sustainable if it could decrease the baseline CDI rate by an ARR of 1.06% or decrease the baseline SSI rate by an ARR of 1.34%. The probability of penicillin testing achieving these ARRs depended on the baseline CDI and SSI rates. When the CDI rate was at least 5% or the SSI rate was at least 7%, penicillin allergy testing was guaranteed to achieve economic sustainability.

CONCLUSION

In patients mislabeled with a penicillin allergy, preoperative penicillin allergy testing may be an economically sustainable option to prevent the unnecessary use of prophylactic clindamycin during otolaryngologic surgery. Current practice guidelines should be modified to recommend penicillin allergy testing in patients with an unconfirmed allergy prior to surgery.

LEVEL OF EVIDENCE

N/A Laryngoscope, 2022.