The impact of penicillin allergy de-labelling on the WHO AWaRe antibiotic categories: a retrospective cohort study

Background: The WHO's AWaRe classification categorizes antibiotics into three stewardship groups: Access, Watch and Reserve. The Access group includes antibiotics with lower resistance potential than antibiotics in the other two groups. The UK five-year AMR strategy has set targets for reducing non-Access antibiotic use. The majority of penicillins are in the Access group and therefore patients with a penicillin allergy record are likely to receive more non-Access antibiotics. This study aimed to quantify the impact of penicillin allergy records on non-Access antibiotic prescribing and to estimate potential reductions in non-Access antibiotic use through penicillin allergy de-labelling.

Methods: Inpatients of a 750-patient-bed UK district general hospital in England prescribed antibiotics between 1^st April 2018 and 31^st March 2019 were included. Variables included: age, sex, co-morbidity, infection treated, antibiotic usage, hospital length of stay, penicillin allergy status. Multivariable logistic regression was used to explore the association between patient characteristics and their receipt of antibiotics in the Access and non-Access groups.

Results: A total of 67,059 antibiotic prescriptions for 23,356 inpatients were analysed. Penicillin allergy records were present in 14.3% of hospital admissions. Patients with a penicillin allergy record were around four times more likely (odds ratio = 4.7) to receive an antibiotic from the non-Access groups (i.e. Reserve and Watch groups). We estimate de-labelling 50% of hospital inpatients with a penicillin allergy record could reduce non-Access antibiotic use by 5.8% and total antibiotic use by 0.86%.

Conclusion: Penicillin allergy records are associated with non-Access antibiotic prescribing. Penicillin allergy de-labelling has potential to reduce non-Access antibiotic use.