Verifying penicillin allergy labels

30 November 2022

Researchers discover that as much as 90% of penicillin allergies labels in Hong Kong are false in a new allergy triage and testing strategy developed by the University of Hong Kong's LKS Faculty of Medicine.

Many patients in Hong Kong have unverified penicillin allergy labels on their medical records, and the consequences for these patients are that penicillin or its derivatives are withheld even though many of them could safely take the drug. An HKUMed team led by Dr Philip Li has pioneered a new penicillin allergy triage and testing strategy, with demonstrated effectiveness and safety in verifying the accuracy of the labels.

Incorrect penicillin allergy labels can effect a multitude of dangerous consequences, so providing accurate evaluations of those with suspected allergies is critical. Traditionally this consists of recording the patient’s drug allergy history and testing performed by allergists. In Hong Kong, the availability of such specialists is low relative to the city's population, which in turn limits public access to testing, and therefore unconfirmed penicillin allergy remains prevalent.

As a solution to the problem, Li’s team designed what is called the ‘Hong Kong Drug Allergy Delabelling Initiative’, or HK-DADI. The new protocol is led by trained nurses who would first interview and evaluate patients with suspected penicillin allergy; the patients would then be triaged into either ‘low-risk’ or ‘non-low-risk’ categories. The low-risk group (accounting for about 70% of all evaluated patients) would attend a dedicated clinic with penicillin allergy testing performed. If these low-risk patients were negative – i.e., non-allergic to penicillin – then they would have their incorrect ‘allergies’ delabelled.

It is most notable that after the team in the study evaluated more than 310 patients, 90% of penicillin allergy labels were found to be incorrect and thus delabelled. Compared with the traditional pathway, this new nurse-led evaluation results in a higher rate of future penicillin use after delabelling (19% vs 32% after an average of 10 months) and mitigated the need for unnecessary allergy skin testing.

“Unfortunately, allergy services are severely limited by the lack of specialists in immunology and allergy in Hong Kong,” Li said. “The HK-DADI represents a novel multi-disciplinary approach using the combined expertise of physicians and nurses to streamline penicillin allergy testing for the majority of patients in need. Hopefully, this is just the first of many much-needed allergy collaborative services to come.”

Findings from this study have also led to the development of new local guidelines for penicillin allergy testing in Hong Kong, enabling non-allergists independently to perform penicillin allergy testing for low-risk patients. Furthermore, new dedicated nurse-led HK-DADI clinics have now been set up across Hong Kong to tackle the tremendous burden of incorrect drug allergy labels across the territory.

Their research is now published in the Journal of Clinical Immunology: In Practice.