Review of Pharmacist Driven Penicillin Allergy Assessments and Skin Testing: A Multi-Center Case-Series

True Rate of Allergy among Pediatric Inpatients with Penicillin Allergy Labels (TRIAL)

Background

Penicillin allergy is a common drug allergy diagnosis in pediatric patients; however, upon appropriate allergy testing, many of these patients are found not to have a true allergy. For patients with a reported allergy, alternative antibiotics are prescribed, which are less effective, more toxic, or more expensive. There is a lack of data evaluating allergies in hospitalized children and comparing allergy assessments conducted by pediatric allergists and pharmacists.

Objective

To estimate the percentage of pediatric patients admitted with reported penicillin allergy who did not have a true penicillin allergy.

Methods

This single-centre prospective cohort study included inpatients between 6 months and 17 years of age, with a documented penicillin allergy, who were admitted to the general pediatric and oncology units of a tertiary care children's hospital between November 2019 and March 2023. The allergy history, evaluation, and risk categorization were performed by pharmacists. The history was reviewed with the allergist, and the patient was then referred, underwent skin testing, or received oral amoxicillin challenge with monitoring for 1 hour.

Results

Thirty patients were included, of whom 29 (97%) had delabelling of their penicillin allergy. Four patients (13%) had delabelling on the basis of history alone, without risk assessment. Twenty-five (83%) of the patients were assessed as having low risk; 24 of these had delabelling following oral challenge, and 1 did not complete the oral challenge because of transfer to another hospital. One patient (3%) was assessed as having moderate risk, with delabelling on the basis of results of skin testing and oral challenge. The pharmacist's and allergist's risk assessments were in agreement in 29 (97%) of the 30 cases.

Conclusions

Pediatric patients, including those with oncologic malignancies, are often mislabelled as having a penicillin allergy. Pharmacists are able to accurately determine true allergy risk and delabel penicillin allergies for pediatric patients in the hospital setting.

Penicillin allergy de-labelling by non-allergists: a comparison of testing protocols

Optimizing penicillin allergy de-labelling (PADL) to ensure patients with an incorrect penicillin allergy record are de-labelled with minimal patient harm is important for antibiotic stewardship. The heterogeneity of inclusion and exclusion criteria in the published penicillin allergy testing protocols risks suboptimal delivery of PADL. We compared the similarities and the differences between non-allergist-delivered PADL testing protocols and make suggestions for harmonization. The observed variation in testing practice has two broad elements: (i) definitions and terminology; and (ii) differences in the acceptability of perceived risk. All direct drug provocation testing (DDPT) protocols included patients with benign delayed rash as eligible for testing, although the remoteness of the rash, and the terminology used to describe the rash, differed. Patients with features of potential IgE reactions were excluded from most DDPT protocols, but not all of them. There was differing advice on how to manage patients who had subsequently tolerated penicillin since the index reaction and differences in which patients were considered ineligible for DDPT due to acuity of illness, comorbidities and concomitant medications. Standardization of the terminology used in penicillin allergy testing protocols and consensus on inclusion and exclusion criteria are required for safe and efficient PADL delivery at scale by non-allergists.

The effectiveness of interventions that support penicillin allergy assessment and delabeling of adult and pediatric patients by nonallergy specialists: a systematic review and meta-analysis

OBJECTIVES

Penicillin allergy records are often incorrect and may result in harm. We aimed to systematically review the effectiveness and safety of nonallergist health care worker delivery of penicillin allergy delabeling.

METHODS

We searched EMBASE/MEDLINE/CINAHL (Ovid), PsycInfo, Web of Science, and Cochrane CENTRAL from inception to January 21, 2022 and unpublished studies and gray literature. The proportion of patients allergic to penicillin delabeled and harmed was calculated using random-effects models.

RESULTS

Overall, 5019 patients were delabeled. Using allergy history alone, 14% (95% confidence interval [CI], 9-21%) of 4350 assessed patients were delabeled without reported harm. Direct drug provocation testing resulted in delabeling in 27% (95% CI, 18-37%) of 4207 assessed patients. Of the 1373 patients tested, 98% were delabeled (95% CI, 97-99%), and nonserious harm was reported in 1% (95% CI, 0-2%). Using skin testing, followed by drug provocation testing, 41% (95% CI, 24-59%) of 2890 assessed patients were delabeled. Of the 1294 tested patients, 95.0% (95% CI, 90-99%) were delabeled, and the reported harm was low (0%; (95% CI 0-1%).

CONCLUSION

Penicillin allergy delabeling by nonallergists is efficacious and safe. The proportion of assessed patients who can be delabeled increases with the complexity of testing method, but substantial numbers can be delabeled without skin testing.

Hong Kong Drug Allergy Delabelling Initiative (HK-DADI) consensus statements for penicillin allergy testing by nonallergists

Introduction

Penicillin allergy testing has been traditionally performed by allergists, but there remains a huge deficit of specialists. A multidisciplinary effort with nonallergists would be invaluable to overcome the magnitude of penicillin allergy labels via the Hong Kong Drug Allergy Delabelling Initiative (HK-DADI). These consensus statements (CSs) offer recommendations and guidance to enable nonallergists to screen for low-risk (LR) patients and perform penicillin allergy testing.

Methods

CSs were formulated by the HK-DADI Group using the Delphi method. An agreement was defined as greater than or equal to 80% consensus.

Results

A total of 26 CSs reached consensus after multiple rounds of Delphi. CSs were categorized into risk assessment, skin testing, drug provocation testing (DPT), and post-testing management. For risk assessment, the essentials of allergy history and exclusion criteria were detailed. Patients with only LR features can proceed with testing by nonallergists. Skin tests should be performed prior to DPT. Details regarding the timing, preparation, and interpretation of skin tests were elaborated. DPT remains the gold standard to diagnose genuine allergy or tolerance and should be performed when there is a low pretest probability following negative skin testing. Details of DPT preparations, dosing protocols, and interpretation were elaborated. For post-testing management, inaccurate allergy labels should be delabeled following negative DPT with proper patient counseling.

Conclusion

CSs support penicillin allergy testing by nonallergists in Hong Kong. LR cases can be managed by nonallergists at Spoke Clinics, with training and support of an allergist-led Hub.