Penicillin Allergy Testing Is Cost-Saving: An Economic Evaluation Study

Penicillin Allergy: Mechanisms, Diagnosis, and Management

Allergy to penicillin can occur via any of the 4 types of Gel-Coombs hypersensitivity reactions, producing distinct clinical histories and physical examination findings. Treatments include penicillin discontinuation, and depending on the type of reaction, epinephrine, antihistamines, and/or glucocorticoids. Most beta-lactams may be safely used in penicillin-allergic patients, with the possible exception of first-generation and second-generation cephalosporins. Penicillin testing includes skin testing, patch testing, and graded challenge. The selection of the type of testing depends on the clinical setting, equipment availability, and type of hypersensitivity reaction. Desensitization may be used in some cases where treatment with penicillins is essential.

Promoting penicillin allergy de-labeling for children attending a hematology clinic

BACKGROUND

Up to 10% of children are reported to be allergic to penicillin, but many allergy labels are unverified and may require formal testing. Inaccurate drug allergy labels are associated with a range of adverse clinical outcomes. Patients with hematological disorders may experience frequent and severe infections; those who have been incorrectly labeled penicillin allergic may benefit from allergy de-labeling (ADL) efforts to facilitate access to beta-lactam antibiotics. We developed a multidisciplinary, pharmacist-driven process that enabled non-allergist trained providers to assess and de-label penicillin allergies in a pediatric hematology center.

METHODS

Volunteers, including physicians, advanced practice providers, nurses, and pharmacists, were trained in skin testing and oral challenge procedures. Patients were identified by review of electronic medical records for penicillin or penicillin-derivative allergy. Patient and family interviews were conducted in cases where a true penicillin allergy was deemed uncertain based on chart review. If allergy could not be de-labeled by chart review or interview alone, patients were offered skin and/or oral challenge testing.

RESULTS

Fifty-nine patients were initially labeled as penicillin allergic. Allergy labels of 11 (19%) were removed by chart review only, and 15 (25%) after conducting interviews. A total of two (3%) patients were ineligible due to contraindications, and five (9%) declined participation. Twenty-six patients (44%) underwent allergy testing (50% skin testing, 50% oral challenge) of which 23 (88%) were negative.

CONCLUSIONS

ADL was possible in most patients previously identified as penicillin allergic. Testing was well tolerated with no serious adverse effects.

The Cost of Developing and Implementing an Antepartum Referral Program for Penicillin Allergy Evaluation at a Single Academic Tertiary Care Hospital

OBJECTIVE

 Approximately 10% of pregnant individuals report a penicillin allergy, yet most are not truly allergic. Allergy verification during pregnancy is safe and recommended; however, many hospitals lack the infrastructure to execute testing. Our aim was to evaluate the cost of developing and implementing a penicillin allergy referral program for pregnant individuals at an academic institution and to compare costs of care between patients who were referred and not referred through the program.

STUDY DESIGN

 We conducted an economic analysis of our institution's antepartum penicillin allergy referral program. We prospectively collected detailed resource utilization data and conducted the analysis from the program's perspective, accounting for costs related to program development, allergy verification, antibiotic cost, and delivery hospitalization. Costs were compared between patients who were referred for evaluation versus patients who were not referred using bivariate tests as well as quantile regression adjusting for baseline differences. A sensitivity analysis was performed for allergy testing cost. All cost estimates were inflation adjusted to 2021 U.S. dollars.

RESULTS

 The startup cost of program development and educational initiatives was $19,920, or 86 per patient. The median allergy evaluation cost was $397 (interquartile range: $303-663). There was no significant difference in maternal (median: $13,579 vs. 13,999, p = 0.94) or neonatal (median: $3,565 vs. 3,577, p = 0.55) delivery hospitalization cost or antibiotic cost (median: $1.57 vs. 3.87, p = 0.10) between referred and nonreferred patients. Overall, the total cost per person did not differ significantly between study groups (median: $18,931 vs. 18,314, p = 0.69).

CONCLUSION

 The cost of developing a penicillin allergy referral program in pregnancy was modest and did not significantly alter short-term cost of care with potential for long-term cost benefit. Verification of a reported penicillin allergy is an integral part of antibiotic stewardship, and the pregnancy period should be utilized as an important opportunity to perform this evaluation.

KEY POINTS

· The cost of developing and implementing an antepartum penicillin allergy referral program is modest.. · Program cost did not significantly alter short-term cost with a potential for long-term cost benefit.. · Penicillin allergy verification is an important part of antibiotic stewardship and should be expanded..

β-Lactam allergy delabeling is safe and saves costs in Primary Care

OBJECTIVE

To determine whether the β-lactam allergy delabeling was safe and cost-saving in Primary Care (PC) patients.

DESIGN

We have conducted a retrospective chart review of PC patients with β-lactam allergy label evaluated in our Allergy Unit between 2017 and 2022. SITE: Allergy Department. Hospital Virgen del Rocio (Sevilla).

PARTICIPANTS

A total of 391 patients labeled for β-lactam allergy in PC were studied.

MAIN MEASUREMENTS

(a) Outcome evaluation of a β-lactam allergy delabeling procedure. (b) A ratio between the total e-prescribed antibiotic cost and the number of treatment days (the experimental daily antibiotic cost or EDAC) before and after delabeling was analyzed in delabeled and truly allergic patients.

RESULTS

The results of skin testing were positive in 9.2% of the reported cases (36 of 391 patients). The reactions to oral provocation challenge (OPC) occurred in 2.14% of the patients who underwent negative skin testing to offending β-lactam (in 15 of 699 OPC). A total of 307 patients (78.5%) were delabeled; 70 (17.9%) had a β-lactam selective response and 14 (3.59%) reacted to both penicillin and cephalosporin. The EDAC before and after the procedure in delabeled patients was significantly lower (0.88 € vs 0.62 €, p<10-3), than that observed in truly allergic group (0.87 € vs. 0.76 €, p=not significant).

CONCLUSION

To delabel β-lactam allergy in Primary Care patients is safe in most patients, cost-saving in antibioticotherapy, and allows identify the main clinical β-lactam allergy phenotypes that benefit from this procedure.

Delabeling of allergy to beta-lactam antibiotics in hospitalized patients: a prospective study evaluating cost savings

BACKGROUND

Patients with a penicillin allergy label are at risk of an associated increase in adverse antibiotic events and hospitalization costs.

AIM

We aimed to study the economic savings derived from the correct diagnosis and delabeling inpatients with suspected beta-lactam allergy, considering the acquisition cost of antimicrobials prescribed during a patient's hospital stay.

METHOD

We prospectively evaluated patients admitted to the University Hospital of Salamanca who had been labeled as allergic to beta-lactams and performed a delabeling study. Subsequently, cost differences between antibiotics administered before and after the allergy study and those derived from those patients who received alternative antibiotics during admission and those who switched to beta-lactams after the allergy study were calculated.

RESULTS

One hundred seventy-seven inpatients labeled as allergic to beta-lactams underwent a delabeling study; 34 (19.2%) were confirmed to have allergy to beta-lactams. Of the total number of patients, 136 (76.8%) received antibiotics during their hospitalization, involving a mean (SD) cost of €203.07 (318.42) and a median (IQR) cost of €88.97 (48.86-233.56). After delabeling in 85 (62.5%) patients, the antibiotic treatment was changed to beta-lactams. In this group of patients, the mean cost (SD) decreased from €188.91 (351.09) before the change to 91.31 (136.07) afterward, and the median cost (IQR) decreased from €72.92 (45.82-211.99) to €19.24 (11.66-168). The reduction was significant compared to the median cost of patients whose treatment was not changed to beta-lactams (p<0.001).

CONCLUSION

Delabeling hospitalized patients represents a cost-saving measure for treating patients labeled as allergic to beta-lactams.

A novel 2-step process for the management of inpatient beta-lactam allergy labels

BACKGROUND

Inpatient beta-lactam allergy labels may increase the unnecessary use of aztreonam and non-beta-lactam antibiotics, which can then lead to more adverse events and increased health care costs, OBJECTIVE: To assess the impact of a novel 2-step process (medication history review followed by risk stratification) on rates of beta-lactam delabeling, aztreonam use, and desensitizations on pediatric, adult, and obstetrics inpatients at a tertiary academic center.

METHODS

We prospectively collected data on 700 patients who received inpatient consultation from the Beta-Lactam Allergy Evaluation Service between August 2021 and July 2022. Patients were delabeled either by medication review alone, drug challenge alone if with a low-risk history, or penicillin skin test followed by drug challenge if with a high-risk history. Generalized linear regression modeling was used to compare aztreonam days of therapy in the intervention year with the 2 prior years. Drug desensitizations were assessed by electronic chart review.

RESULTS

Most of the patients (n = 656 of 700, 94%) had more than or equal to 1 beta-lactam allergy label removed, clarified, or both; 77.9% of these patients (n = 511 of 656) had 587 beta-lactam allergy labels removed. Nearly one-third (n = 149, 27.6%) had 162 allergy labels removed solely by medication history review. All 114 penicillin skin tests performed had negative results, and 98% (8 of 381) of the patients who underwent any drug challenge passed. Only 5.7% of the delabeled patients were relabeled. There was a 27% reduction in aztreonam use (P = .007). Beta-lactam desensitizations were reduced by 80%.

CONCLUSION

A full-time inpatient beta-lactam allergy service using medication history review and risk stratification can safely and effectively remove inpatient beta-lactam allergy labels, reduce aztreonam use, and decrease beta-lactam desensitizations.

Documented Penicillin Allergies on Antibiotic Selection at Pediatric Emergency Department Visits

BACKGROUND

Penicillin or amoxicillin are the recommended treatments for the most common pediatric bacterial illnesses. Allergies to penicillin are commonly reported among children but rarely true. We evaluated the impact of reported penicillin allergies on broad-spectrum antibiotic use overall and for the treatment of common respiratory infections among treat-and-release pediatric emergency department (ED) visits.

METHODS

Retrospective cohort study of pediatric patients receiving antibiotics during a treat-and-release visit at a large, pediatric ED in the northeast from 2014 to 2016. Study exposure was a reported allergy to penicillin in the electronic medical record. Study outcomes were the selection of broad-spectrum antibiotics and alternative (second-line) antibiotic therapy for the treatment of acute otitis media (AOM) and group A streptococcus (GAS) pharyngitis. We used unadjusted and adjusted generalized estimating equation models to analyze the impact of reported penicillin allergies on the selection of broad-spectrum antibiotics. We used unadjusted and adjusted logistic regression models to determine the probability of children with a documented penicillin allergy receiving alternative antibiotic treatments for AOM and GAS.

RESULTS

Among 12,987 pediatric patients, 810 (6.2%) had a documented penicillin allergy. Penicillin allergies increased the odds of children receiving a broad spectrum versus narrow spectrum antibiotic (adjusted odds ratio, 13.55; 95% confidence interval (CI), 11.34-16.18). In our adjusted logistic regression model, the probability of children with a documented penicillin allergy receiving alternative antibiotic treatment for AOM was 0.97 (95% CI, 0.94-0.99) and for GAS was 0.97 (95% CI, 0.92-0.99).

CONCLUSIONS

Antibiotic stewardship efforts in pediatric EDs may consider the delabeling of penicillin allergies particularly among children receiving antibiotics for an acute respiratory infection as a target for intervention.

Penicillin Allergy Testing and Delabeling for Patients Who Are Prescribed Penicillin: A Systematic Review for a World Health Organization Guideline

Secondary prevention with penicillin aims to prevent further episodes of acute rheumatic fever and subsequent development of rheumatic heart disease (RHD). Penicillin allergy, self-reported by 10% of the population, can affect secondary prevention programs. We aimed to assess the role for (i) routine penicillin allergy testing and the (ii) safety of penicillin allergy delabeling approaches in this context. We searched MEDLINE, Embase, CENTRAL, ClinicalTrials.gov, WHO ICTRP, ISRCTN, and CPCI-S to identify the relevant reports. We found 2419 records, but no studies addressed our initial question. Following advice from the WHO-Guideline committee and experts, we identified 6 manuscripts on allergy testing focusing on other populations showing that the prevalence of allergy confirmed by testing was low and the incidence of life-threatening reactions to BPG was very low (< 1-3/1000 individuals treated). A subsequent search addressed penicillin allergy delabeling. This found 516 records, and 5 studies addressing the safety of direct oral drug challenge vs. skin testing followed by drug administration in patients with suspected penicillin allergy. Immediate allergic reactions of minor severity were observed for a minority of patients and occurred less frequently in the direct drug challenge group: 2.3% vs. 11.5%; RR = 0.25, 95%CI 0.15-0.45, P < 0.00001, I2 = 0%. No anaphylaxis or deaths were observed. Severe allergic reactions to penicillin are extremely rare and can be recognized and dealt by trained healthcare workers. Confirmation of penicillin allergy diagnosis or delabeling using direct oral drug challenge or penicillin skin testing seems to be safe and is associated with a low rate of adverse reactions.

Direct oral challenge for immediate and non-immediate beta-lactam allergy in children: A real-world multicenter study

BACKGROUND

Allergy to beta-lactam antibiotics (BLA) is frequently suspected in children, but a drug provocation test (DPT) rules it out in over 90% of cases. Direct oral DPT (DODPT), without skin or other previous tests, is increasingly been used to delabel non-immediate BLA reactions. This real-world study aimed to assess the safety and effectiveness of DODPT in children with immediate and non-immediate reactions to BLAs.

METHODS

Ambispective registry study in children (<15 years), attended between 2016 and 2023 for suspected BLA allergy in 15 hospitals in Spain that routinely perform DODPT.

RESULTS

The study included 2133 patients with generally mild reactions (anaphylaxis 0.7%). Drug provocation test with the implicated BLA was performed in 2014 patients (94.4%): 1854 underwent DODPT (86.9%, including 172 patients with immediate reactions). One hundred forty-five (7.2%) had symptoms associated with DPT, although only four reactions were severe: two episodes of anaphylaxis and two of drug-induced enterocolitis syndrome, which resolved rapidly with treatment. Of the 141 patients with mild reactions in the first DPT, a second DPT was considered in 87 and performed in 57, with 52 tolerating it without symptoms. Finally, BLA allergy was ruled out in 90.9% of the sample, confirmed in 3.4%, and remained unverified, usually due to loss to follow-up, in 5.8%.

CONCLUSIONS

Direct oral DPT is a safe, effective procedure even in immediate mild reactions to BLA. Many reactions observed in DPT are doubtful and require confirmation. Severe reactions are exceptional and amenable to treatment. Direct oral DPT can be considered for BLA allergy delabeling in pediatric primary care.

Development of a Pipeline for Removing Allergy Labels in Patients Undergoing Hematopoietic Stem Cell Transplantation

Penicillin allergy is reported by 10% to 20 % of patients, but when evaluated only 1% to 2% may have a true allergy. Patients undergoing hematopoietic stem cell transplantation (HSCT) have a high likelihood of requiring beta-lactam antibiotics due to increased infection risk, which can be limited by a penicillin allergy label. When a penicillin allergy is recorded, alternatives are needed, including more expensive broader-spectrum antibiotics, with increases in drug-resistant bacteria, longer hospital stays, higher expenditures, and increases in nosocomial infections, such as Clostridium difficile colitis. This group of patients already undergoes extensive pretreatment testing and would especially benefit from allergy delabeling. This study aimed to develop a self-sustaining, low-cost pipeline between an HSCT clinic and an allergy clinic to identify and successfully delabel low-risk patients who endorse an allergy to penicillin, amoxicillin, amoxicillin-clavulanate, piperacillin-tazobactam, or ampicillin before admission to the hospital. We developed a survey to triage allergy risk, identified key stakeholders in building the pipeline, and underwent 4 plan, do, study, act (PDSA) cycles. Changes were made in each of the PDSA cycles to minimize cost and uncompensated provider time, as well as to increase patient retention throughout the pipeline by increasing appointment availability and decreasing reliance on patients to independently progress through the pathway. Of the 410 patients with planned HSCT who were screened over 11 months, 89 (21.7%) were listed as having a penicillin and/or beta lactam allergy. All but 1 (66 of 67; 98.5%) of the participants completed the survey accurately when confirmed by an allergist, and the survey was 100% accurate in predicting delabeling success in low-risk patients. Of eligible patients, 43.8% (n = 39) were successfully delabeled before their transplant date, and 97.4% of these (n = 38) have undergone HSCT to date. This pipeline is maintained by approximately 5 hours of work per week (1 hour of allergy physician time, 4 hours of nurse and/or clinical coordinator time), with no other direct costs. There is an estimated direct savings of at least $1914.93 per patient delabeled. We successfully designed and implemented a pipeline between the HSCT clinic and the allergy clinic as a quality improvement initiative to identify and address high rates of reported beta-lactam allergies. We identified and addressed patient-based factors, logistical, temporal, and financial barriers that impacted patient retention and sustainability. This model is expected to yield significant and sustained cost savings for the healthcare system as well as to improve patient outcomes, and this hypothesis is currently undergoing formal analysis. We anticipate that this model can be used to create a similar pipeline in other healthcare systems for HSCT recipients, as well as patients in other clinical settings, such as oncology and chimeric antigen receptor T cell therapy.

Performance Characteristics of Basophil Activation Tests for Diagnosing Penicillin Allergy: A Meta-Analysis

BACKGROUND

Approximately 10% of the global population identify themselves as penicillin allergic, yet 90% are not truly allergic and could safely tolerate penicillin. There is no simple way to identify these people. Current in vitro diagnostics include specific immunoglobulin E (with a sensitivity of 19% and specificity of 97%) and a basophil activation test (BAT) with undefined sensitivity and specificity.

OBJECTIVE

To define the sensitivity and specificity of BAT in the diagnosis of penicillin allergy METHODS: We searched PubMed and EMBASE from inception to April 2, 2023, for original studies evaluating the performance characteristics of BAT for penicillin allergy in adults. Study selection, data extraction, risk of bias, assessment with QUADAS-2 tool, certainty assessment with Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology were performed independently, in duplicate. Meta-analysis was performed using Reitsma methodology.

RESULTS

Twenty-two studies fulfilled the inclusion criteria. Twelve used the same positive threshold giving a summary point sensitivity 51% (95% confidence interval [95% CI]46%-56%) and specificity 89% (95% CI 85%-93%). Significant risk of bias was identified owing to patient selection. GRADE certainty of evidence rated sensitivity very low due to imprecision and specificity as low. There was great heterogeneity in methods used. Use of 1,000 basophils per test did not improve performance above 500 basophils.

CONCLUSIONS

BAT sensitivity is highly variable across studies and remains too low to be considered as a routine element of clinical practice. BAT specificity is not as good as specific immunoglobulin E in penicillin allergy diagnosis. Significant further work is required in this field before clinical application of BAT in routine practice.

Impact of penicillin allergy labels on surgical site infections in a large UK cohort of gastrointestinal surgery patients

Objectives

Studies in the USA, Canada and France have reported higher surgical site infection (SSI) risk in patients with a penicillin allergy label (PAL). Here, we investigate the association between PALs and SSI in the UK, a country with distinct epidemiology of infecting pathogens and range of antimicrobial regimens in routine use.

Methods

Electronic health records and national SSI surveillance data were collated for a retrospective cohort of gastrointestinal surgery patients at Cambridge University Hospitals NHS Foundation Trust from 1 January 2015 to 31 December 2021. Univariable and multivariable logistic regression were used to examine the effects of PALs and the use of non-β-lactam-based prophylaxis on likelihood of SSI, 30 day post-operative mortality, 7 day post-operative acute kidney injury and 60 day post-operative infection/colonization with antimicrobial-resistant bacteria or Clostridioides difficile.

Results

Our data comprised 3644 patients and 4085 operations; 461 were undertaken in the presence of PALs (11.3%). SSI was detected after 435/4085 (10.7%) operations. Neither the presence of PALs, nor the use of non-β-lactam-based prophylaxis were found to be associated with SSI: adjusted OR (aOR) 0.90 (95% CI 0.65-1.25) and 1.20 (0.88-1.62), respectively. PALs were independently associated with increased odds of newly identified MRSA infection/colonization in the 60 days after surgery: aOR 2.71 (95% CI 1.13-6.49). Negative association was observed for newly identified infection/colonization with third-generation cephalosporin-resistant Gram-negative bacteria: aOR 0.38 (95% CI 0.16-0.89).

Conclusions

No evidence was found for an association between PALs and the likelihood of SSI in this large UK cohort, suggesting significant international variation in the impact of PALs on surgical patients.

Resource utilization and cost assessment of a proactive penicillin allergy de-labeling program for low-risk inpatients

BACKGROUND

Resource utilization and costs can impede proactive assessment and de-labeling of penicillin allergy among inpatients.

METHODS

Our pilot intervention was a proactive penicillin allergy de-labeling program for new inpatients with penicillin allergy. Patients deemed appropriate for a challenge with a low-risk penicillin allergy history were administered 250 mg amoxicillin and monitored for 1 h. We performed an explorative economic evaluation using various healthcare professional wages.

RESULTS

Over two separate 2-week periods between April 2021 and March 2022, we screened 126 new inpatients with a penicillin allergy. After exclusions, 55 were appropriate for formal assessment. 19 completed the oral challenge, and 12 were directly de-labeled, resulting in a number needed to screen of 4 and a number needed to assess of 1.8 to effectively de-label one patient. The assessor's median time in the hospital per day de-labeling was 4h08 with a range of (0h05, 6h45). A single-site annual implementation would result in 715 penicillin allergy assessments with 403 patients de-labeled assuming 20,234 annual weekday admissions and an 8.9% penicillin allergy rate. Depending on the assessor used, the annual cost of administration would be between $21,476 ($53.29 per effectively de-labeled patient) for a pharmacy technician and $61,121 ($151.67 per effectively de-labeled patient) for a Nurse Practitioner or Physician Assistant.

CONCLUSION

A proactive approach, including a direct oral challenge for low-risk in-patients with penicillin allergy, appears safe and feasible. Similar programs could be implemented at other institutions across Canada to increase access to allergy assessment.

Penicillin Allergy Evaluation Should Be Performed Proactively in Patients With a Penicillin Allergy Label

Penicillin allergy is the most common drug allergy in the US population. A penicillin allergy label is associated with poor patient outcomes including increased hospital length of stay, increased perioperative infections, and overall increased mortality. A penicillin allergy evaluation accurately identifies approximately 9 of 10 patients who, despite reporting a history of penicillin allergy, can receive penicillins safely. Penicillin allergy evaluations should be offered proactively to healthy patients during routine visits, including children and pregnant women, in advance of antibiotic need.

Delabeling, safety, and impact of β-lactam allergy testing: A systematic review

Background

To improve β-lactam delabeling outcomes, we need to understand current practice and the evidence base regarding its outcomes, safety, and impact.

Objectives

We sought to assess the existing published evidence reporting on the effectiveness of penicillin allergy testing and delabeling.

Methods

We conducted a systematic review of studies reporting β-lactam delabeling practices and outcomes after testing, including β-lactam use and patient understanding of the delabeling result. Searches of the PubMed, Scopus, and Embase databases; clinical trial registries; and websites of professional organizations were conducted. Data were extracted from the included studies in duplicate, with a third extraction if discrepancies remained.

Results

We included 284 publications (covering 98,316 participants); 173 were prospective studies, with no randomized controlled trials. The overall study quality was low. In all, 95.6% of individuals who underwent provocation testing were delabeled. Factors associated with successful delabeling could not be determined because of significant heterogeneity between studies. Anaphylaxis due to testing occurred in 0.3% of participants (95 of 31,667). Subjects who did not undergo skin testing (6,980 patients in 31 studies) before challenge had higher rates of provocation test positivity (8.8% vs 4.1% [P < .0001]) and anaphylaxis (15.9% vs 2.7% [P < .0001]) than those subjects who underwent skin testing (51,607 patients in 177 studies). Six studies (2.1%) followed patients after testing to assess their adherence to prescribing recommendations. In all, 136 participants (20.6%) were actively avoiding β-lactams despite delabeling.

Conclusions

The available data suggest that penicillin allergy testing is safe and effective in delabeling most individuals, but the evidence base is incomplete and more work is required to assess the role of skin testing and the impact that delabeling is having on prescribing habits.

Direct challenges are the gold standard for most antibiotic allergy evaluations

Antibiotic allergies are frequently encountered in clinical practice, and delabeling of these allergies has individual and public health benefits. This review focuses on the evidence supporting graded challenges without preceding skin testing in adult and pediatric patients to the major groups of antibiotics including penicillins, cephalosporins, sulfamethoxazole, fluoroquinolones, tetracyclines, macrolides, metronidazole, carbapenems, and aztreonam. The cost savings, time savings, and evidence for performing graded challenges outside of an allergy/immunology office are also reviewed for graded challenges to penicillins.

Drug Allergy Alert System in a Spanish University Hospital: Description and Dynamics of Use

INTRODUCTION

The drug allergy alert system reduces the frequency of adverse drug events, although it is subjected to collateral effects, since 80-90% of alerts are not real, and a large percentage of alerts are overridden (46.2-96.2%). We reviewed how the alert system is used at University Hospital Fundación Alcorcon (HUFA).

METHODS

Data were obtained from the drug allergy alert and the alert overriding notification forms (both in the period 2011-20). We also recorded drug allergy diagnoses at HUFA, drug consumption in primary care in 2016. We calculated the incidence of drug allergy alert activation, temporal trends in use, and correlations between the number of drugs in several datasets.

RESULTS

We collected 15,535 alerts. NSAIDs and penicillins were the drugs with the highest number of drug allergy alerts (36.55% and 26.91%, respectively). A correlation was found between the number of drug alerts and the type of drug allergy in HUFA in 2016. Only 6.83% of the alerts were removed, and, of these, 21.77% were reactivated. Approximately 100 overrides were recorded per year from 2016 (6.8% of 8,434 activated alerts during 2014-2020).

CONCLUSIONS

The number of drug allergy alerts recorded via the drug allergy alert system of HUFA correlates with the distribution of drug allergy diagnoses in the hospital, although many of the alerts could be false positives (as per current published evidence). We detected a very low frequency of removed alerts (6.83%), a relevant frequency of reactivations (one quarter), and a very low frequency of overrides (6.8%).

Drug Hypersensitivity Reactions

Drug hypersensitivity reactions are a diverse group of reactions mediated by the immune system after exposure to a drug. The Gell and Coombs classification divides immunologic DHRs into 4 major pathophysiologic categories based on immunologic mechanism. Anaphylaxis is a Type I hypersensitivity reaction that requires immediate recognition and treatment. Severe cutaneous adverse reactions (SCARs) are a group of dermatologic diseases that result from a Type IV hypersensitivity process and include drug reaction with eosinophilia and systemic symptom (DRESS) syndrome, Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP). Other types of reactions are slow to develop and do not always require rapid treatment. Emergency physicians should have a good understanding of these various types of drug hypersensitivity reactions and how to approach the patient regarding evaluation and treatment.

Assessment of Need for Improved Identification of a Culprit Drug in Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis

Importance

Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) is a severe hypersensitivity reaction. Identifying a culprit drug is critical for patient care, yet identification is based on clinical judgment. Data are limited on the accuracy in or approach to identifying a culprit drug.

Objective

To evaluate patient allergy list outcomes, current approaches in identifying culprit drugs, and potential methods of improving culprit drug identification.

Design, Setting, and Participants

This retrospective cohort study spanned 18 years (January 2000 to July 2018), was conducted at Brigham and Women's Hospital and Massachusetts General Hospital (Boston), and included patients with clinically and histologically confirmed cases of SJS/TEN overlap and TEN.

Main Outcomes and Measures

This study descriptively analyzed potential culprits to SJS/TEN, patients' allergy lists, and currently used approaches that led to those lists. It then tested the theoretical contribution of incorporating various parameters to allergy list outcomes.

Results

Of 48 patients (29 women [60.4%]; 4 Asian [8.3%], 6 Black [12.5%], 5 Hispanic [10.4%], and 25 White [52.1%] individuals; median age, 40 years [range, 1-82 years]), the mean (SD) number of drugs taken per patient at disease onset was 6.5 (4.7). Physicians labeled 17 patients as allergic to a single culprit drug. Comparatively, 104 drugs were added to allergy lists across all patients. Physicians' approaches relied largely on heuristic identification of high-notoriety drugs and the timing of drug exposure. Use of a vetted database for drug risk improved sensitivity. Algorithm for Drug Causality for Epidermal Necrolysis scoring was discordant in 28 cases, labeling an additional 9 drugs missed by physicians and clearing 43 drugs labeled as allergens by physicians. Human leukocyte antigen testing could have potentially affected 20 cases. Consideration of infection as a culprit was limited.

Conclusions and Relevance

The results of this cohort study suggest that currently used approaches to identify culprit drugs in SJS/TEN are associated with overlabeling patients allergic to likely nonculprit drugs and less commonly missed possible culprit drugs. Incorporation of a systematized unbiased approach could potentially improve culprit drug identification, although ultimately a diagnostic test is necessary.

Characterizing Antibiotic Allergy Labels in a Large UK Hospital Population to Inform Antimicrobial Stewardship and Delabeling Assessment Strategy

BACKGROUND

Antibiotic allergy labels are important barriers to treatment and antimicrobial stewardship, but their prevalence in UK hospitals is poorly described.

OBJECTIVE

To ascertain the prevalence and characteristics of antibiotic allergy labels in a large UK hospital setting and estimate the proportion of penicillin allergy labels for which point-of-care (POC) delabeling assessment would be appropriate.

METHODS

Electronic health records data were analyzed from all patients treated at Cambridge University Hospitals NHS Foundation Trust in 2019. Validated POC delabeling risk stratification criteria were retrospectively applied to penicillin allergy labels.

RESULTS

Recorded reactions to antibiotics were present in 11.8% of all patients (32,148 of 273,216), 16.3% of inpatients (13,874 of 85,230), and 9.7% of outpatients (18,274 of 187,986). Penicillins were the commonest reaction precipitant described (9.0% of patients; 24,646 of 273,216), followed by sulfonamides/trimethoprim (1.4%; 3869 of 273,216) and macrolides/lincosamides (1.3%; 3644 of 273,216). A total of 3.9% of inpatients had recorded reactions to >1 antibiotic class (3348 of 85,230). Cutaneous manifestations were the most commonly described reaction features (40.7% of labels; 15,821 of 38,902). Of 15,949 labels describing probable or possible penicillin "allergy" with sufficient detail to allow for the retrospective assessment of POC delabeling suitability, 1702 were deemed suitable for removal or downgrading of the label to "intolerance" without further investigation (10.7%), 11,887 were appropriate for POC assessment using an oral penicillin challenge (OPC) or OPC with prior bedside skin testing (74.5%), and 2360 were identified as unsuitable for any form of POC assessment (14.8%).

CONCLUSIONS

Antibiotic allergy labels are highly prevalent in a UK hospital setting. A large proportion of penicillin allergy labels may be suitable for POC delabeling assessment.

Pearls for practice from the 2022 joint task force drug allergy practice parameter

PURPOSE OF REVIEW

To review updated recommendations in the 2022 Drug Allergy Practice Parameters for the evaluation and management of drug hypersensitivity reactions.

RECENT FINDINGS

Adverse drug reactions have become increasingly prominent with the advent of new and emerging pharmacologic therapies. Hypersensitivity reactions encompass a significant proportion of adverse drug reactions and negatively impact both the individual patient and overall health system. Reactions are heterogeneous in presentation and may be immediate (onset of symptoms ≤6 h) or delayed (onset of symptoms >6 h to months) after drug exposure. The 2022 Drug Allergy Practice Parameter provides consensus-based statements for evaluation of hypersensitivity reactions to antibiotics, NSAIDs, cancer chemotherapies, immune checkpoint inhibitors, biologics, and excipients. In general, the guideline highlights the importance of patient history in elucidating the phenotype and severity of the index reaction. Drug challenge remains the gold standard for diagnosis and is increasingly favored over skin testing in patients with nonsevere, nonanaphylactic drug reaction histories.

SUMMARY

The 2022 Drug Allergy Practice Parameter provides an updated framework for physicians to reference in clinical practice when managing patients with drug hypersensitivity reactions.

Penicillin allergy delabeling: Opportunities for implementation and dissemination

Although existing as a safety measure to prevent iatrogenic harm, unconfirmed penicillin allergy labels have a negative impact on personal and public health. One downstream effect of unconfirmed penicillin allergy is the continued emergence and transmission of resistant bacteria and their associated health care costs. Recognizing the consequences of inaccurate penicillin allergy labels, professional and public health organizations have started promoting the adoption of proactive penicillin allergy evaluations, with the ultimate goal of removing the penicillin allergy label when the allergy is disproved, also known as penicillin allergy "delabeling." A penicillin allergy evaluation includes a comprehensive allergy history often followed by drug challenge, sometimes with preceding skin testing. Currently, penicillin allergy delabeling is largely carried out by allergy specialists in outpatient settings. Penicillin allergy delabeling is performed on inpatients, albeit rarely, often at the time of need, as a point-of-care procedure. Access to penicillin allergy evaluation services is limited. Recent studies demonstrate the feasibility of expanding penicillin allergy evaluations and delabeling to internists, pediatricians, emergency medicine physicians, infectious diseases specialists, and clinical pharmacists. However, reducing the impact of mislabeled penicillin allergy will require comprehensive efforts and new investments. In this review, we summarize the current practices of penicillin allergy delabeling and discuss expansion opportunities for penicillin allergy delabeling as quality improvement.

Digital Antibiotic Allergy Decision Support Tool Improves Management of β-Lactam Allergies

BACKGROUND

Frontline providers frequently make time-sensitive antibiotic choices, but many feel poorly equipped to handle antibiotic allergies.

OBJECTIVE

We hypothesized that a digital decision support tool could improve antibiotic selection and confidence when managing β-lactam allergies.

METHODS

A digital decision support tool was designed to guide non-allergist providers in managing patients with β-lactam allergy labels. Non-allergists were asked to make decisions in clinical test cases without the tool, and then with it. These decisions were compared using paired t tests. Users also completed surveys assessing their confidence in managing antibiotic allergies.

RESULTS

The tool's algorithm was validated by confirming its recommendations aligned with that of five allergists. Non-allergist providers (n = 102) made antibiotic management decisions in test cases, both with and without the tool. Use of the tool increased the proportion of correct decisions from 0.41 to 0.67, a difference of 0.26 (95% CI, 0.22-0.30; P < .001). Users were more likely to give full-dose antibiotics in low-risk situations, give challenge doses in medium-risk situations, and avoid the antibiotic and/or consult allergy departments in high-risk situations. A total of 98 users (96%) said the tool would increase their confidence when choosing antibiotics for patients with allergies.

CONCLUSIONS

A point-of-care clinical decision tool provides allergist-designed guidance for non-allergists and is a scalable system for addressing antibiotic allergies, irrespective of allergist availability. This tool encouraged appropriate antibiotic use in low- and medium-risk situations and increased caution in high-risk situations. A digital support tool should be considered in quality improvement and antibiotic stewardship efforts.

Addressing the Challenges of Penicillin Allergy Delabeling With Electronic Health Records and Mobile Applications

Allergy labels are common, often incorrect, and potentially harmful. There are many opportunities for clinical decision support (CDS) tools integrated in the electronic health record (EHR) and mobile apps to address the challenges with drug allergy management, including penicillin allergy delabeling (PADL). Effective delabeling solutions must consider multidisciplinary clinical workflow and multistep processes, including documentation, assessment, plan (eg, allergy testing and referral), record update, drug allergy alert management, and allergy reconciliation over time. Developing a systematic infrastructure to manage allergies across the EHR is critical to improve the accuracy and completeness of a patient's allergy and avoid inadvertently relabeling. Improving the appropriateness and relevancy of drug allergy alerts is important to reduce alert fatigue. Using alerts to guide clinicians on appropriate antibiotic use may reduce unnecessary β-lactam avoidance. To date, EHR CDS tools have facilitated non-allergists to provide PADL at the point of care. A mobile app was shown to support PADL and provide specialist support and education. Future research is needed to standardize, integrate, and evaluate innovative CDS tools in the EHR to demonstrate patient safety and clinical utility and facilitate wider adoption.

Drug Allergy Practice Parameter Updates to Incorporate Into Your Clinical Practice

The drug allergy practice parameter was developed to provide guidance on the diagnosis and management of drug hypersensitivity reactions. It was last updated in 2010. With the growth of research and evidence-based data since then, experts came together to update the practice parameter with a focus on sections that the work group deemed to have significant changes (or were not addressed) in the previous practice parameter. This review is a focused update on aspects of the practice parameter deemed to have the greatest impact on clinical practice and includes significant updates on diagnosis of antibiotic allergy including penicillin, cephalosporin, sulfonamide, fluoroquinolone, and macrolide allergies. Other topics include the evolution in our management approach to patients with aspirin/nonsteroidal anti-inflammatory drug allergy, diagnostic testing for delayed drug hypersensitivity and allergy to chemotherapeutics and biologics, and the key consensus-based statements for clinical practice. Specifically, the updated practice parameter helps allergists understand the place of 1- or 2-step drug challenges that are valuable tools often without the need for skin testing in many clinical situations. A proactive approach to delabeling penicillin allergy as well as unnecessary avoidance of safe antibiotic alternatives for patients with proven penicillin allergy is emphasized. New guidance is provided on management of patients with different phenotypes of aspirin and nonsteroidal anti-inflammatory drug hypersensitivity reactions. Approaches to delayed drug hypersensitivity and use of delayed intradermal and patch testing for specific phenotypes are reviewed. Lastly, practical approaches to management of patients with reactions to chemotherapeutics and biologics are discussed.

Penicillin Allergy

Allergy to penicillin can occur via any of the 4 types of Gel-Coombs hypersensitivity reactions, producing distinct clinical histories and physical examination findings. Treatments include penicillin discontinuation, and depending on the type of reaction, epinephrine, antihistamines, and/or glucocorticoids. Most beta-lactams may be safely used in penicillin-allergic patients, with the possible exception of first-generation and second-generation cephalosporins. Penicillin testing includes skin testing, patch testing, and graded challenge. The selection of the type of testing depends on the clinical setting, equipment availability, and type of hypersensitivity reaction. Desensitization may be used in some cases where treatment with penicillins is essential.

Evaluating the cost-effectiveness of testing pregnant women for penicillin allergy

INTRODUCTION

True penicillin allergy is rare and is commonly incorrectly reported. In fact, less than five percent of patients who report a penicillin allergy will have a currently active clinically-significant IgE- or T-cell-mediated hypersensitivity when appropriately tested. Penicillin is the agent of choice for intrapartum antibiotic prophylaxis to reduce the risk of group B streptococcus early-onset disease in the newborn. Inaccurate penicillin allergy status may lead to inappropriate antibiotic use, as most alternative drugs are more expensive and broader spectrum than penicillin. Penicillin allergy testing has been found to be safe in pregnancy and cost-effective in other patient populations.

OBJECTIVE

To evaluate the cost-effectiveness of penicillin allergy testing and appropriate antibiotic treatment (test then treat strategy) compared to usual care among pregnant women.

METHODS

We developed a decision tree to evaluate the cost of providing appropriate care via a test then treat strategy for pregnant women who report a penicillin allergy, compared to usual care.

RESULTS

Using the test then treat strategy the additional cost to ensure appropriate care for all pregnant women who report a penicillin allergy, was $1122.38 per person. Adopting a test then treat strategy increased the number of appropriate antibiotic use from 7,843/10,000 to 10,000/10,000 simulations.

CONCLUSION

Our results show that a test then treat strategy for pregnant women who report a penicillin allergy is a good-value intervention.

Beta-lactam hypersensitivity diagnosis in ambulatory and hospitalized settings require different approaches

BACKGROUND

Data on beta-lactam hypersensitivity (BLH) are mainly focused on immediate or mild nonimmediate reactions in the ambulatory setting, but limited in patients with concurrent illness and moderate-to-severe nonimmediate reactions in the hospitalized setting.

OBJECTIVE

To investigate the entire spectrum of BLH in Thai tertiary hospital.

METHODS

Clinical characteristics of 357 patients with suspected BLH were evaluated in a 7-year period. Culprit drug identification was performed in 335 patients by combined skin testing, in vitro testing, or drug provocation tests.

RESULTS

The predominant BLH presentations were non-immunoglobulin (Ig)E-mediated reactions with severe cutaneous adverse reactions of 18.9%, and BLH status was definitively confirmed in 18.1%. The most common verified culprits were cephalosporins (34.8%), particularly in hypersensitivity type IV reactions. Natural penicillins were the main implicated drugs in 48.5% of ambulatory patients. In contrast, cephalosporins and carbapenems were the main implicated drugs in hospitalized patients. Non-IgE-mediated anaphylaxis and serum sickness-like reaction remained diagnostically challenged. New generations of beta-lactams, hospitalized patients, recent allergic history, and underlying malignancies or autoimmune diseases were associated with increased BLH risk.

CONCLUSION

At present, cephalosporins are the leading causes of BLH, particularly in non-IgE-mediated reactions. More research on the verification of non-IgE hypersensitivity reactions from new generations of beta-lactams should be better emphasized.

CLINICAL TRIAL REGISTRATION

The registry was approved by the Ethics and Research Committee of the Faculty of Medicine, Chulalongkorn University, and listed on ClinicalTrials.gov (Identifier: NCT01667055; https://www.

CLINICALTRIALS

gov/ct2/show/NCT01667055).

Penicillin Allergy Delabeling Program: an exploratory economic evaluation in the Australian context

BACKGROUND

Internationally, clinical and economic advantages of low-risk penicillin delabelling have been explored, supporting changes to healthcare delivery systems where penicillin delabelling is embedded into inpatient usual care.

AIMS

To determine if economic advantages of low-risk inpatient penicillin delabelling, described in the international literature, are realised in the Australian context.

METHODS

This explorative economic evaluation had prospective patient data collection between January and August 2019, across two Australian health services. Part 1: determine the cost per effectively delabelled patient for Penicillin Allergy Delabeling Program inpatients (PADP cohort) compared with Outpatient Antibiotic Allergy Testing Service outpatients (OAATS cohort). Part 2: a cost analysis to compare hospital costs for inpatients with low-risk penicillin allergy who did (PADP cohort) and did not (usual care cohort) undergo PADP delabelling.

RESULTS

Part 1: the PADP (n = 350) and OAATS (n = 27 patients, n = 36 individual visits) cohorts were comparable. In PADP, costs/proportion delabelled was $20.10/0.98, equating to $20.51 per effectively delabelled patient; in OAATS, it was $181.24/0.50, equating to $362. Compared with OAATS, PADP was associated with savings of $341.97 per effectively delabelled patient, indicating the outpatient testing was the dominated strategy, being more costly and less effective. Part 2: the PADP (n = 218) and usual care (n = 32) cohorts were comparable. Significantly favouring the delabelled PADP cohort, the mean difference per patient was -4.41 days (95% confidence interval: -7.64, -1.18) and -$9467.72 (95% confidence interval: -$15 419.98, -$3515.46).

CONCLUSIONS

Consistent with international literature, delabelling low-risk penicillin allergies in the inpatient setting had economic advantages in the Australian context. Fully powered economic evaluations are urgently required to consolidate these findings.

Improving antimicrobial stewardship with penicillin allergy testing: a review of current practices and unmet needs

Penicillin allergy, the most frequently reported drug allergy, has been associated with suboptimal antibiotic therapy, increased antimicrobial resistance, increased rates of Clostridioides difficile colonization and infection, as well as extended hospital length of stay and increased cost. Although up to 10% of all patients may report penicillin allergy, most penicillin allergies are not confirmed. As such, most patients with a penicillin allergy can still safely use penicillin and related drugs following a more precise assessment. Herein, we review the current practices and unmet needs in penicillin allergy testing. The diagnostic algorithm is mostly based on a clinical history assessment followed by in vivo testing, i.e. skin test and/or drug challenge. As these tests are labour and resource intensive, there is increased interest in point-of-care penicillin allergy de-labelling solutions incorporated into Antimicrobial Stewardship Programmes including digital assessment tools. These can be locally parameterized on the basis of characteristics of target populations, incidence of specific allergies and local antibiotic usage to perform clinical risk stratification. Safely ruling out any residual risk remains essential and in vivo drug challenge and/or skin testing should be systematically encouraged. Gradual understanding and convergence of the risk stratification of the clinical presentation of penicillin allergy is enabling a wider implementation of this essential aspect of antimicrobial stewardship through digitalized decision tools and in vivo testing. More research is needed to deliver point of care in vitro diagnostic tools to democratize this de-labelling practice, which would be highly beneficial to patient care. This progress, together with better education of patients and clinicians about the availability, efficacy and safety of penicillin allergy testing, will increase the dissemination of penicillin allergy assessment as an important component of Antimicrobial Stewardship Programmes.

Management of Infective Endocarditis in People Who Inject Drugs: A Scientific Statement From the American Heart Association

BACKGROUND

The American Heart Association has sponsored both guidelines and scientific statements that address the diagnosis, management, and prevention of infective endocarditis. As a result of the unprecedented and increasing incidence of infective endocarditis cases among people who inject drugs, the American Heart Association sponsored this original scientific statement. It provides a more in-depth focus on the management of infective endocarditis among this unique population than what has been provided in prior American Heart Association infective endocarditis-related documents.

METHODS

A writing group was named and consisted of recognized experts in the fields of infectious diseases, cardiology, addiction medicine, and cardiovascular surgery in October 2021. A literature search was conducted in Embase on November 19, 2021, and multiple terms were used, with 1345 English-language articles identified after removal of duplicates.

CONCLUSIONS

Management of infective endocarditis in people who inject drugs is complex and requires a unique approach in all aspects of care. Clinicians must appreciate that it requires involvement of a variety of specialists and that consultation by addiction-trained clinicians is as important as that of more traditional members of the endocarditis team to improve infective endocarditis outcomes. Preventive measures are critical in people who inject drugs and are cured of an initial bout of infective endocarditis because they remain at extremely high risk for subsequent bouts of infective endocarditis, regardless of whether injection drug use is continued.

BSACI guideline for the set-up of penicillin allergy de-labelling services by non-allergists working in a hospital setting

The Standards of Care Committee of the British Society for Allergy and Clinical Immunology (BSACI) and a committee of experts and key stakeholders have developed this guideline for the evaluation and testing of patients with an unsubstantiated label of penicillin allergy. The guideline is intended for UK clinicians who are not trained in allergy or immunology, but who wish to develop a penicillin allergy de-labelling service for their patients. It is intended to supplement the BSACI 2015 guideline "Management of allergy to penicillin and other beta-lactams" and therefore does not detail the epidemiology or aetiology of penicillin allergy, as this is covered extensively in the 2015 guideline (1). The guideline is intended for use only in patients with a label of penicillin allergy and does not apply to other beta-lactam allergies. The recommendations include a checklist to identify patients at low risk of allergy and a framework for the conduct of drug provocation testing by non-allergists. There are separate sections for adults and paediatrics within the guideline, in recognition of the common differences in reported allergy history and likelihood of true allergy.

Economic burden of drug-induced anaphylaxis: what can we do better?

PURPOSE OF REVIEW

This systematic review evaluates published data related to the economic burden of drug-induced anaphylaxis (DIA) to understand preventive cost saving measures that could reduce the burden of these conditions.

RECENT FINDINGS

Although DIA has a relevant societal impact, there are limited and heterogenous available data related to its cost. Direct costs related to the management of acute phase of DIA was estimated by $529.6 to $3125, depending on the number of emergency room visits/hospitalizations, emergency kits and transports in ambulance. Direct costs of investigations of DIA varied from $288 to $2292.95 and the desensitization was estimated by $6796. Main variables for this were: personnel, allergy screening procedures, medical consumables and space cost. The mean indirect cost was based on a mean absenteeism of 3 days per DIA corresponding to $381.2.

SUMMARY

More than reviewing the published data, we were able to identify variables that, if correctly managed, can reduce the economic burden of DIA, such as adjusting the timing of referral and etiological diagnosis, identification of potential risk and/or co-factors, correct written recommendations to patients. The evidence presented highlights the need of optimization of healthcare patients to patients suffering from DIA.

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.

Reconciling Allergy Information in the Electronic Health Record After a Drug Challenge Using Natural Language Processing

Background

Drug challenge tests serve to evaluate whether a patient is allergic to a medication. However, the allergy list in the electronic health record (EHR) is not consistently updated to reflect the results of the challenge, affecting clinicians' prescription decisions and contributing to inaccurate allergy labels, inappropriate drug-allergy alerts, and potentially ineffective, more toxic, and/or costly care. In this study, we used natural language processing (NLP) to automatically detect discrepancies between the EHR allergy list and drug challenge test results and to inform the clinical recommendations provided in a real-time allergy reconciliation module.

Methods

This study included patients who received drug challenge tests at the Mass General Brigham (MGB) Healthcare System between June 9, 2015 and January 5, 2022. At MGB, drug challenge tests are performed in allergy/immunology encounters with routine clinical documentation in notes and flowsheets. We developed a rule-based NLP tool to analyze and interpret the challenge test results. We compared these results against EHR allergy lists to detect potential discrepancies in allergy documentation and form a recommendation for reconciliation if a discrepancy was identified. To evaluate the capability of our tool in identifying discrepancies, we calculated the percentage of challenge test results that were not updated and the precision of the NLP algorithm for 200 randomly sampled encounters.

Results

Among 200 samples from 5,312 drug challenge tests, 59% challenged penicillin reactivity and 99% were negative. 42.0%, 61.5%, and 76.0% of the results were confirmed by flowsheets, NLP, or both, respectively. The precision of the NLP algorithm was 96.1%. Seven percent of patient allergy lists were not updated based on drug challenge test results. Flowsheets alone were used to identify 2.0% of these discrepancies, and NLP alone detected 5.0% of these discrepancies. Because challenge test results can be recorded in both flowsheets and clinical notes, the combined use of NLP and flowsheets can reliably detect 5.5% of discrepancies.

Conclusion

This NLP-based tool may be able to advance global delabeling efforts and the effectiveness of drug allergy assessments. In the real-time EHR environment, it can be used to examine patient allergy lists and identify drug allergy label discrepancies, mitigating patient risks.

Instruction and Simulation to Improve Pharmacy Students' Knowledge and Confidence Regarding Assessment of Penicillin Allergies

Objective. To evaluate pharmacy students' knowledge of and confidence regarding penicillin allergy assessment and skin testing (PAAST) before and after a focused didactic instruction and simulation (FDIS).Methods. A multicenter, quasi-experimental, cross-sectional survey study was performed among pharmacy students before and after FDIS on PAAST at two schools of pharmacy. The FDIS on PAAST consisted of an infectious disease faculty-led seminar, student-led penicillin allergy counseling interviews, penicillin skin testing simulation, and case studies to assess penicillin allergy scenarios and management. An anonymous, voluntary, electronic survey was distributed to students (n=159) before and after the FDIS. The pre- and post-intervention survey contained 10 PAAST knowledge-based questions and multi-step, five-point Likert scale statements related to students' confidence in PAAST. The post-intervention survey also evaluated students' perceptions of the FDIS on PAAST. Descriptive statistics were performed, and the Student t test was used to compare pre- and post-intervention responses.Results. One hundred forty-three surveys were completed, resulting in a survey response rate of 90%. Students' PAAST knowledge scores (mean±SD) increased overall following the FDIS on PAAST (6.67±1.51 vs 7.81±1.39). Knowledge scores increased considerably for questions related to penicillin allergy consequences, cross-reactivity, and correct steps of PAAST. Pharmacy students' PAAST confidence scores (mean±SD) also improved following the interactive instruction and simulation (2.30±0.7 vs 3.22±0.67) with considerable confidence increases in penicillin skin testing. Pharmacy students' perceptions of the FDIS on PAAST were also positive overall.Conclusion. Pharmacy students' knowledge and confidence of PAAST improved following FDIS. This may be an effective strategy to implement PAAST education during pharmacy school.

Understanding Penicillin Allergy, Cross-reactivity, and Antibiotic Selection in the Preoperative Setting

Penicillin allergies are reported by 8% to 15% of the US population, but up to 95% of these allergies do not correspond to a true allergy when tested. Recent studies have demonstrated that having a penicillin allergy label (PAL) results in a 50% increased odds of surgical site infection among patients reporting a penicillin allergy entirely attributable to the use of a beta-lactam alternative antibiotic (primarily clindamycin or vancomycin). This study provides a review of the prevalence of PAL, the cross-reactivity with cefazolin, immunogenic components of cefazolin and penicillin, and current guidelines for preoperative antibiotic selection in patients with PALs. On understanding these principles, a new set of guidelines and a risk stratification tool are proposed for assessing allergies and determining appropriate antibiotic choice, dosage, and timing in the orthopaedic preoperative setting.

A Continuing Education Activity Durably Addressed Knowledge Gaps Related to Penicillin Allergies Among Pharmacists and Pharmacy Technicians

Background: Penicillin allergy is one of the most frequent self-reported allergies; however, only about 10% of reported allergies are accurate. Objectives: Through the creation of a continuing pharmacy education (CPE) activity, we sought to assess knowledge gaps and comfort levels in the management of penicillin allergies. Methods: A 1-hour enduring-content CPE activity was offered as an interactive course from September 20, 2019, to September 20, 2020. Participants completed 3 surveys (pre-survey, post-survey, and follow-up survey). Participants were pharmacists and pharmacy technicians who completed, at a minimum, the activity and both pre- and post-surveys. The primary outcome was the percentage of participants scoring >80% on knowledge-based questions on the post-survey compared with the pre-survey. Secondary outcomes included pre-post comparisons on knowledge-based questions, participants’ self-report of an allergy, and comfort levels dispensing cephalosporins in a patient with a self-reported penicillin allergy. Results: A total of 389 participants completed the CPE activity, with 176 included for analysis. Significantly more participants scored >80% on knowledge-based questions on the post-survey compared with the pre-survey (71.6% vs 22.7%, P < .001). There was no significant difference between the percentage of participants scoring >80% on the post-survey and the follow-up survey (71.6% vs 65%, P = .119). The majority of participants (74%) felt comfortable dispensing a cephalosporin in a patient with a penicillin allergy on the pre-survey, with similar percentages on the post- and follow-up surveys (77% and 90%, respectively). Conclusion: A targeted continuing education program improved overall knowledge, which was sustained for up to 2 months.

Drug Hypersensitivity Reactions

Drug hypersensitivity reactions are a diverse group of reactions mediated by the immune system after exposure to a drug. The Gell and Coombs classification divides immunologic DHRs into 4 major pathophysiologic categories based on immunologic mechanism. Anaphylaxis is a Type I hypersensitivity reaction that requires immediate recognition and treatment. Severe cutaneous adverse reactions (SCARs) are a group of dermatologic diseases that result from a Type IV hypersensitivity process and include drug reaction with eosinophilia and systemic symptom (DRESS) syndrome, Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP). Other types of reactions are slow to develop and do not always require rapid treatment. Emergency physicians should have a good understanding of these various types of drug hypersensitivity reactions and how to approach the patient regarding evaluation and treatment.

Development and Validation of a Mobile Clinical Decision Support Tool for the Diagnosis of Drug Allergy in Adults: The Drug Allergy App

BACKGROUND

Penicillin allergy overdiagnosis has been associated with inappropriate antibiotic prescribing, increased antimicrobial resistance, worse clinical outcomes, and increased health care costs.

OBJECTIVE

To develop and validate a questionnaire-based algorithm built in a mobile application to support clinicians in collecting accurate history of previous reactions and diagnosing drug allergy appropriately.

METHODS

A survey was completed by 164 medical and nonmedical prescribers to understand barriers to best practice. Based on the survey recommendations, we created a 10-item questionnaire-based algorithm to allow classification of drug allergy history in line with the National Institute for Health and Care Excellence guidelines on drug allergy. The algorithm was incorporated into a mobile application and retrospectively validated using anonymized clinical databases at regional immunology and dermatology centers in Manchester, United Kingdom.

RESULTS

A total of 55.2% of prescribers (95% confidence interval, 47% to 63.4%) thought it impossible to draw a firm conclusion based on history alone and 59.4% (95% CI, 51.4% to 67.5%) believed that regardless of the details of the penicillin allergy history, they would avoid all β-lactams. A drug allergy mobile application was developed and retrospectively validated, which revealed a low risk for misclassification of outcomes compared with reference standard drug allergy investigations in the allergy and dermatology clinics.

CONCLUSIONS

Perceived lack of time and preparedness to collect an accurate drug allergy history appear to be important barriers to appropriate antimicrobial prescribing. The Drug Allergy App may represent a useful clinical decision support tool to diagnose drug allergy correctly and support appropriate antibiotic prescribing.

Investigation of enzymes and solvents in the production process of 6-ammonium penicillanic acid (6-APA) in industry to reduce costs and improve production conditions

In this study, the optimization of the amount of enzyme consumed in the enzymatic phase of substitution of butanol solvent instead of methanol in the powder washing phase after filtration was investigated. To perform this study, different amounts of the enzyme penicillin G amidase (PGA) were tested in reactions with the same conditions. The highest efficiency was observed in the reaction that the ratio of penicillin powder to the amount of enzyme was 2:1. In this reaction, for every 100 g of penicillin consumed, 50 g of the PGA was used. Replacement of butanol instead of methanol after filtration, the powder obtained from this step was washed with butanol instead of methanol and the powder obtained from this step was examined after drying. The resulting solvent powder was very small and the drying speed of the powder increased compared to the time of methanol usage. Optimizing the amount of enzyme in this process due to the high cost of the enzyme made this reaction more economically viable at the end of this study. In this study, for the first time, butanol was used as a suitable substitute for methanol and the ratio of enzyme use to penicillin powder was optimized. This research deals with the future perspective in the field of research in this regard.

Role of clinical history in beta-lactam hypersensitivity

PURPOSE OF REVIEW

Understand how the clinical history has been used to risk stratify patients reporting a beta-lactam allergy, both in clinical care pathways and predictive models.

RECENT FINDINGS

Drug allergy clinical care pathways have emerged as a safe and effective method of stratifying patients with a reported beta-lactam allergy into risk categories, with 'low-risk' patients able to proceed straight to direct challenges or test doses. These methods have streamlined antibiotic stewardship policies and penicillin allergy de-labeling. However, how to define 'low-risk' has been subject to much debate. New research has developed predictive models that utilize the clinical history to assess a patient's true risk of beta-lactam allergy.

SUMMARY

The clinical history has long been an essential part of drug allergy evaluation and has proven invaluable within the past decade in the development of drug allergy clinical pathways. Evidence-based predictive models that use the clinical history to assess a patient's true risk of beta-lactam allergy offer tremendous promise, but differ in crucial areas such as the populations they study, the predictor variables they use, and the ultimate accuracy they attain. These models highlight key aspects of the drug allergy history and pave the way for future large-scale research.

Frequency of severe reactions following penicillin drug provocation tests: A Bayesian meta-analysis

BACKGROUND

Patients with a penicillin allergy label tend to have worse clinical outcomes and increased healthcare use. Drug provocation tests (DPT) are the gold-standard in the diagnostic workup of penicillin allergy, but safety concerns may hinder their performance. We aimed to assess the frequency of severe reactions following a DPT in patients with reported allergy to penicillins or other β-lactams.

METHODS

We performed a systematic review, searching MEDLINE, Scopus, and Web of Science. We included primary studies assessing participants with a penicillin allergy label who underwent a DPT. We performed a Bayesian meta-analysis to estimate the pooled frequency of severe reactions to penicillin DPTs. Sources of heterogeneity were explored by subgroup and metaregression analyses.

RESULTS

We included 112 primary studies which included a total of 26,595 participants. The pooled frequency of severe reactions was estimated at 0.06% (95% credible interval [95% CrI] = 0.01%-0.13%; I2  = 57.9%). Most severe reactions (80/93; 86.0%) consisted of anaphylaxis. Compared to studies where the index reaction was immediate, we observed a lower frequency of severe reactions for studies assessing non-immediate index reactions (OR = 0.05; 95% CrI = 0-0.31). Patients reporting anaphylaxis as their index reaction were found to be at increased risk of developing severe reactions (OR = 13.5; 95% CrI = 7.7-21.5; I2  = 0.3%). Performance of direct DPTs in low-risk patients or testing with the suspected culprit drug were not associated with clinically relevant increased risk of severe reactions.

CONCLUSIONS

In patients with a penicillin allergy label, severe reactions resulting from DPTs are rare. Therefore, except for patients with potentially life-threatening index reactions or patients with positive skin tests-who were mostly not assessed in this analysis -, the safety of DPTs supports their performance in the diagnostic assessment of penicillin allergy.

Analysis of the Costs Associated With the Elective Evaluation of Patients Labelled as Allergic to Beta-Lactams or Nonsteroidal Antiinflamatory Agents

Introduction: Being labelled as allergic to different drugs results in patients receiving other treatments, which are more toxic, less effective and more expensive. We aimed to analyze different studies of the costs of drug hypersensitivity assessment.

Methods: A bibliographic search on studies regarding this issue was performed, including the available scientific evidence up to June 2020. We searched three databases with terms related to costs and allergy testing in drug hypersensitivity reactions.

Results: Our search revealed 1,430 publications, of which 20 met the inclusion criteria. In the manuscript, prospective studies evaluating the costs of the evaluation of patients with suspected allergy to beta-lactams or non-steroidal anti-inflammatory drugs are analyzed. Also, comment is made on the costs associated with incorrect labeling as non-steroidal anti-inflammatory drug or penicillin hypersensitivity.

Conclusions: Taking all costs into account, the study of drug hypersensitivity is not expensive, particularly considering the economic and clinical consequences of labeling a patient with hypersensitivity to drugs.