Penicillin skin testing in patients with a history of beta-lactam allergy

Oral challenge vs routine care to assess low-risk penicillin allergy in critically ill hospital patients (ORACLE): a pilot safety and feasibility randomised controlled trial

PURPOSE

Critically ill patients are vulnerable to penicillin allergy labels that may be incorrect. The validity of skin testing in intensive care units (ICUs) is uncertain. Many penicillin allergy labels are low risk, and validated tools exist to identify those amenable to direct oral challenge. This pilot randomised controlled trial explored the feasibility, safety, and validity of direct enteral challenge for low-risk penicillin allergy labels in critical illness.

METHODS

Consenting patients with a low-risk penicillin allergy label (PAL) (PEN-FAST risk assessment score < 3) in four ICUs (Melbourne, Australia) were randomised 1:1 to penicillin (250 mg amoxicillin or implicated penicillin) direct enteral challenge versus routine care (2-h post-randomisation observation for each arm). Repeat challenge was performed post -ICU in the intervention arm. Patients were reviewed at 24 h and 5 days after each challenge/observation.

RESULTS

We screened 533 patients. 130 (24.4%) were eligible and 80/130 (61.5%) enrolled (age median 64.5 years (interquartile range, IQR 53.5, 74), PEN-FAST median 1 (IQR 0,1)), with 40 (50%) randomised to direct enteral challenge. A positive challenge rate of 2.5% was identified. No antibiotic-associated serious adverse events were identified. 32/40 (80%) received a repeat challenge (zero positive). Post-randomisation, 13 (32%) of the intervention arm and 4 (10%) of the control arm received penicillin (odds ratio, OR 4.33 [1.27, 14.78] p = 0.019).

CONCLUSION

These findings support the safety, validity, and feasibility of direct enteral challenge for critically ill patients with PEN-FAST assessed low-risk penicillin allergy. The absence of false negative results was confirmed by subsequent negative repeat challenges. A relatively low recruitment to screened ratio suggests that more inclusive eligibility criteria and integration of allergy assessment into routine ICU processes are needed to optimise allergy delabelling in critical illness.

Predicting Penicillin Allergy: A United States Multicenter Retrospective Study

BACKGROUND

Using the reaction history in logistic regression and machine learning (ML) models to predict penicillin allergy has been reported based on non-US data.

OBJECTIVE

We developed ML positive penicillin allergy testing prediction models from multisite US data.

METHODS

Retrospective data from 4 US-based hospitals were grouped into 4 datasets: enriched training (1:3 case-control matched cohort), enriched testing, nonenriched internal testing, and nonenriched external testing. ML algorithms were used for model development. We determined area under the curve (AUC) and applied the Shapley Additive exPlanations (SHAP) framework to interpret risk drivers.

RESULTS

Of 4777 patients (mean age 60 [standard deviation: 17] years; 68% women, 91% White, and 86% non-Hispanic) evaluated for penicillin allergy labels, 513 (11%) had positive penicillin allergy testing. Model input variables were frequently missing: immediate or delayed onset (71%), signs or symptoms (13%), and treatment (31%). The gradient-boosted model was the strongest model with an AUC of 0.67 (95% confidence interval [CI]: 0.57-0.77), which improved to 0.87 (95% CI: 0.73-1) when only cases with complete data were used. Top SHAP drivers for positive testing were reactions within the last year and reactions requiring medical attention; female sex and reaction of hives/urticaria were also positive drivers.

CONCLUSIONS

An ML prediction model for positive penicillin allergy skin testing using US-based retrospective data did not achieve performance strong enough for acceptance and adoption. The optimal ML prediction model for positive penicillin allergy testing was driven by time since reaction, seek medical attention, female sex, and hives/urticaria.

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.

The Quality and Management of Penicillin Allergy Labels in Pediatric Primary Care

BACKGROUND AND OBJECTIVES

Penicillin allergy labels are the most common drug allergy label. The objective of this study was to describe the quality and management of penicillin allergy labels in the pediatric primary care setting.

METHODS

Retrospective chart review of 500 of 18 015 children with penicillin allergy labels born from January 1, 2010 to June 30, 2020 randomly selected from an outpatient birth cohort from Texas Children's Pediatrics and Children's Hospital of Philadelphia networks. Penicillin allergy risk classification ("not allergy," "low risk," "moderate or high risk," "severe risk," "unable to classify") was determined based on documentation within (1) the allergy tab and (2) electronic healthcare notes. Outcomes of allergy referrals and penicillin re-exposure were noted.

RESULTS

Half of penicillin allergy labels were "unable to classify" based on allergy tab documentation. Risk classification agreement between allergy tabs and healthcare notes was fair (Cohen's ĸ = 0.35 ± 0.02). Primary care physicians referred 84 of 500 (16.8%) children to an allergist, but only 54 (10.8%) were seen in allergy clinic. All children who were challenged (25 of 25) passed skin testing. Removal of allergy labels was uncommon (69 of 500, 13.8%) but occurred more often following allergy appointments (26 of 54, 48%) than not (43 of 446, 9.6%, P < .001). Children delabeled by primary care physicians were as likely to tolerate subsequent penicillin-class antibiotics as those delabeled by an allergist (94% vs 93%, P = .87).

CONCLUSIONS

Penicillin allergy documentation within the allergy tab was uninformative, and children were infrequently referred to allergists. Future quality improvement studies should improve penicillin allergy documentation and expand access to allergy services.

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.

Infectious Diseases Management in Wound Care Settings: Common Causative Organisms and Frequently Prescribed Antibiotics

GENERAL PURPOSE

To provide information about the management of infected wounds in wound care settings.

TARGET AUDIENCE

This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.

LEARNING OBJECTIVES/OUTCOMES

After participating in this educational activity, the participant will:1. Identify a host factor that may predispose a patient to a wound infection as well as characteristics of each stage of wound infection.2. Distinguish a common organism that causes early, acute wound infections and explain the preferred method for obtaining a wound specimen for culture.3. Apply knowledge of commonly prescribed antibiotics in wound care settings.

The Impact of Reported β-Lactam Allergy on Clinical Outcomes and Antibiotic Use Among Solid Organ Transplant Recipients

Background

Reported β-lactam allergies (BLAs) are common and frequently inaccurate, but there are limited data on the clinical implications of BLA among solid organ transplant (SOT) recipients. We examined the impact of BLA on clinical outcomes and antibiotic use among SOT recipients.

Methods

This retrospective cohort study included adult patients undergoing single-organ heart, kidney, liver, lung, or pancreas transplant at a United States academic medical center from 1 April 2017 to 31 December 2020. Demographic and clinical data were collected from the electronic health record. Multivariate median regression was performed to evaluate the association between BLA and days alive and out of the hospital in the first 180 days posttransplant (DAOH180). Multivariate logistic regression was performed to evaluate the association between BLA and antibiotic use.

Results

Among 1700 SOT recipients, 285 (16.8%) had a BLA at the time of transplant. BLA was not associated with DAOH180 (adjusted median difference, -0.8 days [95% confidence interval {CI}, -2.7 to 1.2]; P = .43). Patients with BLA were more likely to receive intravenous vancomycin (adjusted odds ratio [aOR], 1.8 [95% CI, 1.3-2.6]; P < .001), clindamycin (aOR, 9.9 [95% CI, 5.1-18.9]; P < .001), aztreonam (aOR, 19.6 [95% CI, 5.9-64.4]; P < .001), fluoroquinolones (aOR, 3.8 [95% CI, 2.8-5.0]; P < .001), or aminoglycosides (aOR, 3.9 [95% CI, 2.5-6.2]; P < .001).

Conclusions

BLA was associated with use of β-lactam alternative antibiotics but not DAOH180 among SOT recipients.

Management of Beta-Lactam Antibiotics Allergy: A Real-Life Study

Beta-lactam allergy is a common problem in everyday medical practice and is recognized as a major public health issue. Carrying this label frequently leads to the avoidance of all beta-lactam antibiotics, favoring the use of other less preferred classes of antibiotics, that are more expensive and associated with more side effects and increased antimicrobial resistance. Therefore, delabeling a beta-lactam allergy is part of antimicrobial stewardship programs. Herein, we retrospectively examined the clinical records of 576 patients who were referred to our center for a label of allergy to beta-lactam antibiotics and were systematically investigated following a standardized algorithm. Our main aim was to evaluate the frequency of confirmed immediate- and delayed-type allergy to commonly prescribed subclasses of beta-lactam antibiotics (penicillin and cephalosporin), as well as the negative predictive value (NPV) and the sensitivity of skin tests. Our secondary aims were to examine the safety of beta-lactam skin testing and drug challenge. We identified that 260 patients reported a history of immediate reactions, 131 of delayed reactions, and 114 of unknown timing or mechanism of reactions. Following assessment and testing, 86 (18.3%) patients had a confirmed allergy to any beta-lactam antibiotics; 63 (13.4%) with an immediate- and 23 (4.9%) with a delayed-type reaction. Most frequently identified confirmed allergy was to penicillins (65 patients), followed by cephalosporins (21 patients). When immediate-type reactions were examined, NPV of skin tests were 96.3% and 100% for penicillins and cephalosporins, respectively. When delayed reactions were considered, NPV were 91.9 and 87.5% for penicillins and cephalosporins, respectively. Evaluation of the safety of skin tests according to the standardized procedure showed that systemic allergic reactions occurred in only 0.7% of skin tests and in 3.1% of drug challenges. Overall, our data indicate that only 18.3% of patients with a beta-lactam allergy label have a confirmed allergy and non-allergic patients can be safely delabeled through allergic workup based on skin tests and drug challenge. This approach supports the policy of saving second-line antibiotics through a standardized allergy workup.

Outcomes in hospitalised patients with sepsis, severe sepsis or septic shock and reported penicillin allergy: a retrospective cohort study

OBJECTIVE

To determine outcomes in hospitalised patients with sepsis and reported penicillin allergy (PcnA).

DESIGN

Observational retrospective cohort study using data from electronic health records.

SETTING

A large single health system with 11 hospitals of small, medium and large sizes including a 630-bed tertiary care teaching hospital.

PARTICIPANTS

Patients (n=5238) ≥18 years of age, hospitalised with sepsis, severe sepsis or septic shock between 1 January 2016 and 31 December 2018, received antibacterial agents, and had documented PcnA status. Patients <18 years of age at admission were excluded.

OUTCOME MEASURES

Primary outcomes evaluated were inpatient mortality and 30-day mortality posthospital discharge. Secondary outcomes were hospital length of stay, 30-day readmissions, duration of antibiotic use, rate of Clostridium difficile infection and total cost of care.

RESULTS

There was no difference in outcomes including inpatient or 30-day mortality, hospital length of stay, in-hospital antibiotic duration, C. difficile infection, total cost of care and 30-day readmission rate between patients labelled with a PcnA vs patients who did not report PcnA (non-PcnA).

CONCLUSION

In this retrospective single health system study, there was no difference in key outcomes including inpatient or 30-day mortality in patients admitted with sepsis and reported PcnA compared with patients who reported no PcnA.

Anaphylaxis to Drugs, Biological Agents, and Vaccines

Anaphylaxis is a multi-system syndrome resulting from the release of mediators from mast cells and basophils. Drugs are common causes. Anaphylaxis to certain drugs, vaccines, and biological agents present clinical challenges, and merit referral to a board-certified allergist/immunologist for further evaluation and management.

A comprehensive assessment of carbapenem use across 90 Veterans Health Administration hospitals with defined stewardship strategies for carbapenems

OBJECTIVES

Carbapenems are an important target for antimicrobial stewardship (AS) efforts. In this study, we sought to compare different hospital-based strategies for improving carbapenem use.

METHODS

We analysed a cohort of all patients hospitalized at Veterans Health Administration (VHA) acute care hospitals during 2016 and a mandatory survey that characterized each hospital's carbapenem-specific AS strategy into one of three types: no strategy (NS), prospective audit and feedback (PAF) or restrictive policies (RP). Carbapenem use was compared using risk-adjusted generalized estimating equations that accounted for clustering within hospitals. Two infectious disease (ID) physicians independently performed manual chart reviews in 425 randomly selected cases. Auditors assessed carbapenem appropriateness with an assessment score on Day 4 of therapy.

RESULTS

There were 429 062 admissions in 90 sites (24 NS, 8 PAF, 58 RP). Carbapenem use was lower at PAF than NS sites [rate ratio (RR) 0.6 (95% CI 0.4-0.9); P = 0.01] but similar between RP and NS sites. Carbapenem prescribing was considered appropriate/acceptable in 215 (50.6%) of the reviewed cases. Assessment scores were lower (i.e. better) at RP than NS sites (mean 2.3 versus 2.7; P < 0.01) but did not differ significantly between NS and PAF sites. ID consultations were more common at PAF/RP than NS sites (51% versus 29%; P < 0.01). ID consultations were associated with lower (i.e. better) assessment scores (mean 2.3 versus 2.6; P < 0.01).

CONCLUSIONS

In this VHA cohort, PAF strategies were associated with lower carbapenem use and ID consultation and RP strategies were associated with more appropriate carbapenem prescribing. AS and ID consultations may work complementarily and hospitals could leverage both to optimize carbapenem use.

Prevalence of drug allergy in South Australia

INTRODUCTION

Drug allergy is commonly reported in patient notes and electronic health records. The prevalence of self-reported drug allergy in the general Australian population has not previously been studied.

METHODS

We surveyed a representative sample of the South Australian adult population regarding their own perception of drug allergy, including drug type and severity as well as the use of medical alert devices. Data were weighted to correspond to age and sex of the South Australian population.

RESULTS

22.2% of adults in South Australia consider themselves allergic to one or more drugs, 9.3% declared themselves to be allergic to penicillin, 5% to an antibiotic other than penicillin, and 13% to one or more antibiotics. Drug allergy and penicillin allergy was significantly more prevalent in females, and increased with age. Thirteen percent of those with an antibiotic allergy reported a severe reaction, of whom 27% wore a medical notification device. Of those allergic to penicillin, 75% had their index reaction more than 10 years ago and did not report severe features.

DISCUSSION

Self-reported drug allergy is common in the general population, as it is in medical clinic and hospital populations. The majority of those reporting penicillin allergy would be considered low-risk and suitable for delabelling procedures. This article is protected by copyright. All rights reserved.

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.

Preoperative Allergy Testing for Patients Reporting Penicillin and Cephalosporin Allergies is Cost-Effective in Preventing Infection after Total Knee and Hip Arthroplasty

BACKGROUND

Routine preoperative allergy testing in patients reporting penicillin and cephalosporin allergies increases the number able to receive cefazolin, which should reduce the risk of infection after total knee and hip arthroplasty (TKA/THA), but it remains unclear whether this practice is cost-effective. Using a break-even analysis, we calculated the cost-effectiveness of routine preoperative allergy testing for infection prevention in total joint arthroplasty patients reporting penicillin and cephalosporin allergies.

METHODS

The cost of a penicillin allergy evaluation, the cost of revision arthroplasty for prosthetic joint infection (PJI), and baseline rates of PJI in patients receiving a noncefazolin antibiotic in the perioperative period were derived from existing literature. A break-even economic model using these variables was constructed to calculate the absolute risk reduction (ARR) in infection rate needed for preoperative allergy testing to be cost-effective. The number needed to treat (NNT) was calculated from the ARR.

RESULTS

Preoperative allergy testing before TKA and THA in patients reporting penicillin and cephalosporin allergies was cost-effective if the initial infection rate decreased by an ARR of 0.810% (NNT = 123) and 0.655% (NNT = 153) for TKA and THA, respectively. Cost-effectiveness was maintained with varying allergy consultation costs, infection rates, and costs associated with PJI treatment.

CONCLUSION

Routine preoperative allergy testing and clearance are cost-effective infection prevention strategies among patients reporting penicillin and cephalosporin allergies in the setting of elective joint arthroplasty. Widespread adoption of this practice may considerably reduce the economic and societal burden associated with prosthetic infections.

The democratization of de-labeling: a review of direct oral challenge in adults with low-risk penicillin allergy

INTRODUCTION

Penicillin antibiotic allergy labels (AALs) are common and lead to significant negative health and health system outcomes. Direct oral challenge offers a rapid and cost-effective way of removing inaccurate AALs and improving outcomes.

AREAS COVERED

A narrative review (Medline, May 2020) of direct oral challenge in low-risk penicillin allergy in adults is described, and the evidence for the safety and efficacy of this approach in inpatients, outpatients, and special patient groups is presented.

EXPERT OPINION

Whilst the current literature demonstrates the safety and efficacy of direct oral challenge in de-labeling low-risk penicillin allergy in adults, novel approaches are needed to improve access to antibiotic allergy assessment and address the growing global need.

Hospital Infection Control: Clostridioides difficile

Clostridioides difficile remains a leading cause of healthcare-associated infection. Efforts at C. difficile prevention have been hampered by an increasingly complex understanding of transmission patterns and a high degree of heterogeneity among existing studies. Effective prevention of C. difficile infection requires multimodal interventions, including contact precautions, hand hygiene with soap and water, effective environmental cleaning, use of sporicidal cleaning agents, and antimicrobial stewardship. Roles for probiotics, avoidance of proton pump inhibitors, and isolation of asymptomatic carriers remain poorly defined.

Is a Reported Penicillin Allergy Sufficient Grounds to Forgo the Multidimensional Antimicrobial Benefits of β-Lactam Antibiotics?

The majority of patients with reported penicillin allergy are not allergic when tested or challenged. Penicillin allergy testing has been shown to significantly reduce annual healthcare expenditures. Data have emerged showing β-lactams have multidimensional antibacterial effects in vivo, far beyond what is appreciated in standard bacteriological susceptibility testing media. These include enhancing bacterial killing by the innate immune system. Supporting the clinical relevance of these secondary underappreciated effects are recent clinical and pharmacoeconomic analyses that show worse outcomes in patients with reported penicillin allergies who receive non-β-lactam antibiotics when compared to their non-penicillin-allergic counterparts. This is particularly relevant in the treatment of Staphylococcus aureus bacteremia. This article reviews the tremendous advantages offered by β-lactam therapy and makes a strong case that the debunking of false penicillin allergies through a detailed allergy history and penicillin allergy testing should be a vital component of antimicrobial stewardship practices.

No. 275-Antibiotic Prophylaxis in Gynaecologic Procedures

OBJECTIVE

To review the evidence and provide recommendations on antibiotic prophylaxis for gynaecologic procedures.

OUTCOMES

Outcomes evaluated include need and effectiveness of antibiotics to prevent infections in gynaecologic procedures.

EVIDENCE

Medline and The Cochrane Library were searched for articles published between January 1978 and January 2011 on the topic of antibiotic prophylaxis in gynaecologic procedures. Results were restricted to systematic reviews, randomized control trials/ controlled clinical trials, and observational studies. Searches were updated on a regular basis and incorporated in the guideline to June 2011. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The quality of evidence obtained was rated using the criteria described in the Report of the Canadian Task Force on Preventative Health Care (Table 1).

BENEFITS, HARMS, AND COSTS

Guideline implementation should result in a reduction of cost and related harm of administering antibiotics when not required and a reduction of infection and related morbidities when antibiotics have demonstrated a proven benefit.

RECOMMENDATIONS

Penicillin allergy skin testing as an antibiotic stewardship intervention reduces alternative antibiotic exposures in hematopoietic stem cell transplant recipients

BACKGROUND

Antibiotic allergy de-labeling using penicillin allergy skin testing (PAST) can reduce the use and cost of alternative, non-β-lactam antibiotics in general inpatient populations. This strategy's role in hematopoietic stem cell transplant (HSCT) recipients is unclear.

METHODS

This study aimed to determine the effect of a pre-transplant PAST protocol on antibiotic use, days of therapy (DOT), and cost in an immunocompromised population at a single center from 7/1/2010-2/1/2019. Patients who received chimeric antigen receptor (CAR) T-cell therapy and those who underwent transplantation in the outpatient setting were excluded.

RESULTS

Of 1560 patients who underwent inpatient HSCT during the study period, 208 reported β-lactam allergy (136/844 [16%] pre- and 72/716 [10%] post-implementation; P < .001). PAST was performed on 7% and 54% of HSCT recipients pre- and post-implementation, respectively. Only two positive PAST were noted. There were no adverse reactions to PAST. There were no significant differences in the disease and transplant characteristics between the two groups. Days of therapy and cost of alternative antibiotics significantly decreased post-implementation (mean 788 vs 627 days, P = .01; mean $24 425 vs $17 518, P = .009).

CONCLUSION

Penicillin allergy skin testing adjudicates reported β-lactam allergy in HSCT recipients, lowering use, DOT, and cost of alternative antibiotics and promoting effective formulary agents to treat immunocompromised HSCT recipients.

No. 247-Antibiotic Prophylaxis in Obstetric Procedures

OBJECTIVE

To review the evidence and provide recommendations on antibiotic prophylaxis for obstetrical procedures.

OUTCOMES

Outcomes evaluated include need and effectiveness of antibiotics to prevent infections in obstetrical procedures.

EVIDENCE

Published literature was retrieved through searches of Medline and The Cochrane Library on the topic of antibiotic prophylaxis in obstetrical procedures. Results were restricted to systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies. Searches were updated on a regular basis and articles published from January 1978 to June2009 were incorporated in the guideline. Current guidelines published by the American College of Obstetrics and Gynecology were also incorporated. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The evidence obtained was reviewed and evaluated by the Infectious Diseases Committee of the Society of Obstetricians and Gynaecologists of Canada under the leadership of the principal authors, and recommendations were made according to guidelines developed by the Canadian Task Force on Preventive Health Care (Table 1).

BENEFITS, HARMS, AND COSTS

Implementation of this guideline should reduce the cost and harm resulting from the administration of antibiotics when they are not required and the harm resulting from failure to administer antibiotics when they would be beneficial.

SUMMARY STATEMENTS

RECOMMENDATIONS.

A EAACI drug allergy interest group survey on how European allergy specialists deal with β-lactam allergy

An accurate diagnosis of β-lactam (BL) allergy can reduce patient morbidity and mortality. Our aim was to investigate the availability of BL reagents, their use and test procedures in different parts of Europe, as well as any differences in the diagnostic workups for evaluating subjects with BL hypersensitivity. A survey was emailed to all members of the EAACI Drug Allergy Interest Group (DAIG) between February and April 2016, and the questionnaire was meant to study the management of suspected BL hypersensitivity. The questionnaire was emailed to 82 DAIG centres and answered by 57. Amoxicillin alone or combined to clavulanic acid were the most commonly involved BL except in the Danish centre, where penicillin V was the most frequently suspected BL. All centres performed an allergy workup in subjects with histories of hypersensitivity to BL: 53 centres (93%) followed DAIG guidelines, two national guidelines and two local guidelines. However, there were deviations from DAIG recommendations concerning allergy tests, especially drug provocation tests. A significant heterogeneity exists in current practice not only among countries, but also among centres within the same country. This suggests the need to re-evaluate, update and standardize protocols on the management of patients with suspected BL allergy.

Penicillin Allergy Evaluation: A Prospective, Multicenter, Open-Label Evaluation of a Comprehensive Penicillin Skin Test Kit

BACKGROUND

Ten percent of the population claims an allergy to penicillin, but 90% of these individuals are not allergic. Patients labeled as penicillin-allergic have higher medical costs, longer hospital stays, are more likely to be treated with broad-spectrum antibiotics, and develop drug-resistant bacterial infections. Most penicillin skin test reagents are not approved by the Food and drug Administration or readily available to evaluate patients labeled penicillin-allergic.

OBJECTIVE

To determine the negative predictive value (NPV) of the Penicillin Skin Test Kit containing the major allergenic determinant (penicilloyl polylysine), a minor determinant mixture (penicillin G, penicilloate, penilloate), and amoxicillin, produced according to Food and Drug Administration standards.

METHODS

This was a prospective, multicenter, open-label investigation of penicillin skin testing using the Penicillin Skin Test Kit. Skin test-negative subjects were challenged with 250 mg amoxicillin, whereas skin test-positive patients were not challenged. The primary end point was NPV of the Penicillin Skin Test Kit, defined as the percentage of subjects with negative skin test results who did not experience an IgE-dependent reaction within 72 hours of amoxicillin challenge.

RESULTS

In total, 455 patients with a history of penicillin allergy underwent skin testing and 63 (13.8%) had 1 or more positive test results; 65% of the positive test results were to the minor determinant mixture and/or amoxicillin alone. In the per protocol group of 373 skin test-negative subjects, 8 developed potential IgE-dependent reactions following oral amoxicillin challenge, translating to an NPV of 97.9% (95% CI, 95.8-99.1; P < .0001). All but 1 of the reactions was mild or moderate, and most subjects who required treatment received only antihistamines.

CONCLUSIONS

The Penicillin Skin Test Kit, containing all relevant penicillin allergenic determinants, demonstrated very high NPV. Removal of a penicillin allergy label in a large majority of currently mislabeled patients has substantial personal and public health implications.

Management of a surgical patient with a label of penicillin allergy: narrative review and consensus recommendations

Unsubstantiated penicillin-allergy labels are common in surgical patients, and can lead to significant harm through avoidance of best first-line prophylaxis of surgical site infections and increased infection with resistant bacterial strains. Up to 98% of penicillin-allergy labels are incorrect when tested. Because of the scarcity of trained allergists in all healthcare systems, only a minority of surgical patients have the opportunity to undergo testing and de-labelling before surgery. Testing pathways can be modified and shortened in selected patients. A variety of healthcare professionals can, with appropriate training and in collaboration with allergists, provide testing for selected patients. We review how patients might be assessed, the appropriate testing strategies that can be used, and the minimum standards of safe testing.

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

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

Inpatient β-lactam test-dose protocol and antimicrobial stewardship in patients with a history of penicillin allergy

BACKGROUND

Penicillin allergy is the most commonly reported drug allergy in hospitalized patients, resulting in increased second-line antibiotic use, nosocomial infections, and health care use. Given that most patients are not truly allergic, a safe strategy that empowers the admitting physician is needed.

OBJECTIVE

To assess the effect on antibiotic prescribing practices for hospitalized patients with penicillin allergy using a validated intervention.

METHODS

An intervention was implemented to educate health care professionals on management of patients with penicillin allergy using a validated risk stratification algorithm to guide testing and antibiotic use. Thirty days of control data using current standard of care was compared with 60 days of postintervention data measuring documentation of penicillin allergy history and antibiotic selection.

RESULTS

The relative use of cephalosporin and penicillin antibiotics increased by 121.2% (P = .03) and 256% (P = .04), respectively, without an increase in adverse drug reactions. There was a decrease in the use of broad-spectrum antibiotics: vancomycin, 67.2% (P = .04); quinolones, 33.3% (P = .31); carbapenems, 81.9% (P = .08); and aztreonam, 73.8% (P = .18).

CONCLUSION

The antibiotic choice in patients admitted to the hospital with a reported penicillin allergy can be improved by better evaluation of the allergy history and the use of a risk stratification guideline.

No 275 - Antibioprophylaxie dans le cadre d'interventions gynécologiques

OBJECTIF

Analyser les données et formuler des recommandations sur l'antibioprophylaxie dans le cadre d'interventions gynécologiques.

ISSUES

Parmi les issues évaluées, on trouvait la nécessité du recours aux antibiotiques et leur efficacité pour ce qui est de la prévention des infections dans le cadre d'interventions gynécologiques. RéSULTATS: Des recherches ont été menées dans Medline et The Cochrane Library afin d'en tirer les articles publiés entre janvier 1978 et janvier 2011 sur le sujet de l'antibioprophylaxie dans le cadre d'interventions gynécologiques. Les résultats ont été restreints aux analyses systématiques, aux essais comparatifs randomisés / essais cliniques comparatifs et aux études observationnelles. Les recherches ont été mises à jour de façon régulière et intégrées à la directive clinique jusqu'en juin 2011. La littérature grise (non publiée) a été identifiée par l'intermédiaire de recherches menées dans les sites Web d'organismes s'intéressant à l'évaluation des technologies dans le domaine de la santé et d'organismes connexes, dans des collections de directives cliniques, dans des registres d'essais cliniques et auprès de sociétés de spécialité médicale nationales et internationales.

VALEURS

La qualité des résultats a été évaluée au moyen des critères décrits dans le rapport du Groupe d'étude canadien sur les soins de santé préventifs (Tableau 1). AVANTAGES, DéSAVANTAGES ET COûTS: La mise en œuvre de la directive clinique devrait entraîner une baisse des coûts et des torts liés à l'administration superflue d'antibiotiques, ainsi qu'une atténuation des infections et des morbidités connexes dans les cas où il a été démontré que l'administration d'antibiotiques confère un avantage pour la patiente. RECOMMANDATIONS.

Penicillin allergy de-labelling ahead of elective surgery: feasibility and barriers

BACKGROUND

Around 10-15% of the in-patient population carry unsubstantiated 'penicillin allergy' labels, the majority incorrect when tested. These labels are associated with harm from use of broad-spectrum non-penicillin antibiotics. Current testing guidelines incorporate both skin and challenge tests; this is prohibitively expensive and time-consuming to deliver on a large scale. We aimed to establish the feasibility of a rapid access de-labelling pathway for surgical patients, using direct oral challenge.

METHODS

'Penicillin allergic' patients, recruited from a surgical pre-assessment clinic, were risk-stratified using a screening questionnaire. Patients at low risk of true, immunoglobulin E (IgE)-mediated allergy were offered direct oral challenge using incremental amoxicillin to a total dose of 500 mg. A 3-day course was completed at home. De-labelled patients were followed up to determine antibiotic use in surgery, and attitudes towards de-labelling were explored.

RESULTS

Of 219 patients screened, 74 were eligible for inclusion and offered testing. We subsequently tested 56 patients; 55 were de-labelled. None had a serious reaction to the supervised challenge, or thereafter. On follow-up, 17 of 19 patients received appropriate antimicrobial prophylaxis during surgery. Only three of 33 de-labelled patients would have been happy for the label to be removed without prior specialist testing.

CONCLUSION

Rapid access de-labelling, using direct oral challenge in appropriately risk-stratified patients, can be incorporated into the existing surgical care pathway. This provides immediate and potential long-term benefit for patients. Interest in testing is high among patients, and clinicians appear to follow clinic recommendations. Patients are unlikely to accept removal of their allergy label on the basis of history alone.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: AN17/92982.

Penicillin minor determinants: History and relevance for current diagnosis

OBJECTIVE

To review the history of the penicillin minor determinants and evaluate their relevance for current diagnosis.

DATA SOURCES

Skin testing to detect immunoglobulin E (IgE) sensitivity to penicillins in patients with a history of penicillin allergy has been the subject of more than 55 years of published research involving tens of thousands of patients.

STUDY SELECTIONS

Selection of data was based on its relevance to the objective of this article.

RESULTS

It was established early on that testing with the major penicilloyl determinant using the polyvalent penicilloyl-polylysine (PPL) is negative in a substantial portion (10% to 64%, including recent increases) of those at risk for immediate hypersensitivity reactions. A variety of minor penicillin determinants are clinically significant in that their use in skin testing is essential to detect all those at risk. In particular, a minor determinant mixture of benzylpenicillin, benzylpenicilloate, and benzylpenilloate, used in conjunction with PPL, has been shown in numerous studies to achieve an average negative predictive value (NPV) of 97.9% in history-positive patients. Benzylpenicillin alone, as the sole minor determinant, leaves many skin test-positive patients undiscovered. Use of amoxicillin as an additional minor determinant reagent appears to identify another 2% to 8% of skin test-positive patients in some populations.

CONCLUSION

IgE skin testing, using both the major and appropriate minor determinants of penicillin, can identify, with a high degree of reliability (NPV ∼97%), penicillin allergy history-positive patients who can receive beta-lactam antibiotics without concern for serious acute allergy, including anaphylaxis. The few false-negative skin tests reported globally are largely confined to minor, self-limited cutaneous reactions.

Incidence of cephalosporin-induced anaphylaxis and clinical efficacy of screening intradermal tests with cephalosporins: A large multicenter retrospective cohort study

BACKGROUND

Few studies have investigated the incidence of anaphylaxis induced by individual or structurally similar cephalosporins. The aims of the study were to assess the incidence of cephalosporin-induced anaphylaxis and evaluate the clinical efficacy of screening skin tests.

METHODS

In this retrospective cohort study, we obtained information on total cephalosporin use and cephalosporin-induced anaphylaxis in intravenous cephalosporin recipients in 12 general hospitals between 2013 and 2015. Cephalosporins were divided into 4 groups according to similar side-chain structures. The incidence of cephalosporin-induced anaphylaxis was assessed for each cephalosporin, cephalosporin generation, and side-chain group. To verify the efficacy of screening intradermal tests (IDT) with cephalosporin, the 12 hospitals were assigned to the intervention or control group depending on whether they performed screening IDT before the administration of cephalosporins.

RESULTS

We identified 76 cases of cephalosporin-induced anaphylaxis with 1 123 345 exposures to intravenous cephalosporins (6.8 per 100 000 exposures), and the incidence of fatal anaphylaxis by cephalosporin was 0.1 cases per 100 000 exposures. The highest incidences of anaphylaxis occurred in the ceftizoxime (13.0 cases per 100 000 exposures) and side-chain group 1 (cefepime, cefotaxime, ceftizoxime, ceftriaxone, and cefuroxime; 9.3 per 100 000). There was no case of anaphylaxis induced by cefoxitin, cefmetazole, cefminox, and cefotiam. The clinical effectiveness of routine screening IDT was not significant (P = .06).

CONCLUSIONS

The incidence of cephalosporin-induced anaphylaxis differed according to individual drugs and side-chain structure. Screening IDT showed no clinical efficacy at a population level.

Improving Aztreonam Stewardship and Cost Through a Penicillin Allergy Testing Clinical Guideline

Background

Patients reporting penicillin allergy often receive unnecessary and costly broad-spectrum alternatives such as aztreonam with negative consequences. Penicillin allergy testing improves antimicrobial therapy but is not broadly used in hospitals due to insufficient testing resources and short-term expenses. We describe a clinical decision support (CDS) tool promoting pharmacist-administered penicillin allergy testing in patients receiving aztreonam and its benefits toward antimicrobial stewardship and costs.

Methods

A CDS tool was incorporated into the electronic medical record, directing providers to order penicillin allergy testing for patients receiving aztreonam. An allergy-trained pharmacist reviewed orders placed through this new guideline and performed skin testing and oral challenges to determine whether these patients could safely take penicillin. Data on tests performed, antibiotic utilization, and cost-savings were compared with patients tested outside the new guideline as part of our institution's standard stewardship program.

Results

The guideline significantly increased penicillin allergy testing among patients receiving aztreonam from 24% to 85% (P < .001) while reducing the median delay between admission and testing completion from 3.31 to 1.05 days (P = 0.008). Patients tested under the guideline saw a 58% increase in penicillin exposure (P = .046). Institutional aztreonam administration declined from 2.54 to 1.47 administrations per 1000 patient-days (P = .016). Average antibiotic costs per patient tested before and after CDS decreased from $1265.81 to $592.08 USD, a 53% savings.

Conclusions

Targeting penicillin allergy testing to patients on aztreonam yields therapeutic and economic benefits during a single admission. This provides a cost-effective model for inpatient testing.

Systematic review of professional liability when prescribing β-lactams for patients with a known penicillin allergy

OBJECTIVE

To describe medical negligence and malpractice cases in which a patient with a known penicillin allergy received a β-lactam and experienced an adverse reaction related to the β-lactam.

DATA SOURCES

Lexis-Nexus, Westlaw, and Google Scholar were searched.

STUDY SELECTIONS

Medical negligence and malpractice cases were eligible for inclusion if they met the following criteria: the plaintiff had a known penicillin allergy, received a β-lactam, and experienced an adverse event. All United States federal and state cases were eligible.

RESULTS

Twenty-seven unique cases met the inclusion criteria. Eighteen cases involved the receipt of a penicillin-based antibiotic; of these cases with a known legal outcome, the plaintiff (patient or representative) prevailed or settled in 3 cases and defendants (providers) prevailed in 7 cases. Seven cases involved the receipt of a cephalosporin; of these cases with a known legal outcome, the plaintiff settled with physicians before trial in 1 case and defendants prevailed in 3 cases. Two cases involved the receipt of a carbapenem. Defendants prevailed in one case and the legal outcome of the other case is unknown. In cases in which the defense successfully moved for summary judgment, judges cited a lack of scientific evidence demonstrating a cephalosporin or carbapenem was contraindicated for a patient with a penicillin allergy.

CONCLUSION

The cases with published legal outcomes found limited professional liability for clinicians who prescribed cephalosporins or carbapenems to a patient with a known penicillin allergy. These results may decrease the litigation fears of practitioners and risk managers within health care systems.

Influence of Reported Penicillin Allergy on Mortality in MSSA Bacteremia

Background

Penicillin allergy frequently impacts antibiotic choice. As beta-lactams are superior to vancomycin in treating methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia, we examined the effect of reported penicillin allergy on clinical outcomes in patients with MSSA bacteremia.

Methods

In this retrospective cohort study of adults with MSSA bacteremia admitted to a large tertiary care hospital, outcomes were examined according to reported penicillin allergy. Primary outcomes included 30-day and 90-day mortality rates. Multivariable regression models were developed to quantify the effect of reported penicillin allergy on mortality while adjusting for potential confounders.

Results

From 2010 to 2015, 318 patients with MSSA bacteremia were identified. Reported penicillin allergy had no significant effect on adjusted 30-day mortality (odds ratio [OR], 0.73; 95% confidence interval [CI], 0.29-1.84; P = .51). Patients with reported penicillin allergy were more likely to receive vancomycin (38% vs 11%, P < .01), but a large number received cefazolin regardless of reported allergy (29 of 66, 44%). Mortality rates were highest among nonallergic patients receiving vancomycin (22.6% vs 7.4% for those receiving beta-lactams regardless of reported allergy, P < .01). In multivariable analysis, beta-lactam receipt was most strongly associated with survival (OR, 0.26; 95% CI, 0.12-0.54).

Conclusions

Reported penicillin allergy had no significant effect on 30- or 90-day mortality. Non-penicillin-allergic patients receiving vancomycin for treatment of MSSA bacteremia had the highest mortality rates overall. Receipt of a beta-lactam was the strongest predictor of survival. These results underscore the importance of correct classification of patients with penicillin allergy and appropriate treatment with a beta-lactam when tolerated.

Diagnosing and managing patients with drug hypersensitivity

INTRODUCTION

Diagnosing and managing drug hypersensitivity is challenging because there are no clear limits between different types of drug reactions. Distinguishing between type A (predictable) and type B (hypersensitivity) reactions when a drug is introduced on the market is not easy. When many people use a drug, adverse reactions can occur, conditioned by diverse genetic profiles, viral infections or concomitant therapy. Occasionally the only tool clinicians have on which to base the diagnosis is the clinical history. Skins tests or in vitro tests sometimes have low sensitivity or are unavailable, and drug provocation tests may be dangerous or strictly forbidden in case of severe cutaneous reactions. Areas covered: This paper reviews the diagnosis and management of the two main types of immunological reactions: IgE-mediated immediate drug hypersensitivity reactions (IDHRs) and non-immediate drug hypersensitivity reactions (NIDHRs). Expert commentary: Although Europe and the United States use different diagnostic methods, patients with history of drug hypersensitivity must avoid the suspicious drug, and clinicians must assess tolerance to safe alternatives under medical surveillance. Sometimes desensitization may be required. There is a consensus about the need to perform genetic testing for specific drugs and give patients proper documentation to prevent future exposure to culprit drugs.

Evaluation of Penicillin Allergy in the Hospitalized Patient: Opportunities for Antimicrobial Stewardship

PURPOSE OF REVIEW

Penicillin allergy is often misdiagnosed and is associated with adverse consequences, but testing is infrequently done in the hospital setting. This article reviews historical and contemporary innovations in inpatient penicillin allergy testing and its impact on antimicrobial stewardship.

RECENT FINDINGS

Adoption of the electronic medical record allows rapid identification of admitted patients carrying a penicillin allergy diagnosis. Collaboration with clinical pharmacists and the development of computerized clinical guidelines facilitates increased testing and appropriate use of penicillin and related β-lactams. Education of patients and their outpatient providers is the key to retaining the benefits of penicillin allergy de-labeling. Penicillin allergy testing is feasible in the hospital and offers tangible benefits towards antimicrobial stewardship. Allergists should take the lead in this endeavor and work towards overcoming personnel limitations by partnering with other health care providers and incorporating technology that improves the efficiency of allergy evaluation.

Penicillin and Beta-Lactam Hypersensitivity

Ten percent of patients report penicillin allergy, but more than 90% of these individuals can tolerate penicillins. Skin testing remains the optimal method for evaluation of possible IgE-mediated penicillin allergy and is recommended by professional societies, as the harms for alternative antibiotics include antimicrobial resistance, prolonged hospitalizations, readmissions, and increased costs. Removal of penicillin allergy leads to decreased utilization of broad-spectrum antibiotics, such as fluoroquinolones and vancomycin. There is minimal allergic cross-reactivity between penicillins and cephalosporins. IgE-mediated allergy to cephalosporins is usually side-chain specific and may warrant graded challenge with cephalosporins containing dissimilar R1 or R2 group side chains.

Clinical outcomes following inpatient penicillin allergy testing: A systematic review and meta-analysis

BACKGROUND

A documented penicillin allergy is associated with increased morbidity including length of hospital stay and an increased incidence of resistant infections attributed to use of broader-spectrum antibiotics. The aim of the systematic review was to identify whether inpatient penicillin allergy testing affected clinical outcomes during hospitalization.

METHODS

We performed an electronic search of Ovid MEDLINE/PubMed, Embase, Web of Science, Scopus, and the Cochrane Library over the past 20 years. Inpatients having a documented penicillin allergy that underwent penicillin allergy testing were included.

RESULTS

Twenty-four studies met eligibility criteria. Study sample size was between 24 and 252 patients in exclusively inpatient cohorts. Penicillin skin testing (PST) with or without oral amoxicillin challenge was the main intervention described (18 studies). The population-weighted mean for a negative PST was 95.1% [CI 93.8-96.1]. Inpatient penicillin allergy testing led to a change in antibiotic selection that was greater in the intensive care unit (77.97% [CI 72.0-83.1] vs 54.73% [CI 51.2-58.2], P<.01). An increased prescription of penicillin (range 9.9%-49%) and cephalosporin (range 10.7%-48%) antibiotics was reported. Vancomycin and fluoroquinolone use was decreased. Inpatient penicillin allergy testing was associated with decreased healthcare cost in four studies.

CONCLUSIONS

Inpatient penicillin allergy testing is safe and effective in ruling out penicillin allergy. The rate of negative tests is comparable to outpatient and perioperative data. Patients with a documented penicillin allergy who require penicillin should be tested during hospitalization given its benefit for individual patient outcomes and antibiotic stewardship.

Epidemiology of anaphylaxis at a tertiary care center: A report of 730 cases

BACKGROUND

Recent data reveal that the rate of anaphylaxis is increasing and suggest that idiopathic anaphylaxis may account for most of these cases.

OBJECTIVE

To determine the pattern of anaphylaxis at a tertiary care referral center.

METHODS

A retrospective electronic medical record review spanning 12 years (2002-2013) identified patients with anaphylaxis.

RESULTS

Of the 4,777 records reviewed, 730 patients met our anaphylaxis definition. Median age was 34.0 years; 72.7% were adults, 58.6% were female, and 86.8% were white. Median time to evaluation by an allergist was 8.8 months. Foods were the most common cause (29.9%), followed by Hymenoptera venom (24.6%), idiopathic anaphylaxis (13.7%), and medications (13.3%). The most common foods were peanuts (23.9%), tree nuts (21.6%), shellfish (16.1%), and egg and milk (both 10.1%). The most common cause of anaphylaxis in adults was Hymenoptera venom. The most frequent symptoms were urticaria and/or angioedema, reported in 84.7% of cases. Atopy was present in 43.8%. In 15.4% of cases, anaphylaxis was not the chief reason for the office visit.

CONCLUSION

We found food allergy was the most common overall cause of anaphylaxis, with peanut the most frequent food trigger. Idiopathic anaphylaxis was not the most common cause but accounted for 13.7% of all cases. Approximately 1 in 6 cases of anaphylaxis may be missed if a comprehensive evaluation is not performed.