Penicillin allergy in Hong Kong

Abstract

Penicillins (belonging to the beta-lactam class of antibiotics) are one of the most frequently prescribed class of medications as well as the most common implicated culprit of drug allergy. Around 10% of Western populations have suspected penicillin allergies, however, most of these “allergy” labels have found to be inaccurate and most patients can actually tolerate penicillins after appropriate allergy evaluation. Misdiagnosis of penicillin allergy is dangerous and associated with a myriad of adverse outcomes, including obligatory use of less-effective antibiotic alternatives, increased mortality and hospitalisation, higher healthcare costs, as well as development of multi-drug resistant microorganisms. Unfortunately, Hong Kong is still lagging behind the rest of the world in drug allergy research. Despite being an important and growing global health issue, the local epidemiology or impact of suspected and true penicillin allergies in Hong Kong (and most of Asia) remains unknown. More robust epidemiological data to determine and understand the burden and differences of penicillin allergy, especially in Asia, are urgently needed. Similarly, few studies have investigated the clinical predictors of genuine penicillin allergy, with previous reports mostly based on self-reported patient histories rather than confirmed cases after formal allergic evaluation. Furthermore, the adverse effect of incorrect penicillin allergy labels as well as the benefits of delabelling have rarely been investigated among Asian populations. Given the marked aging population in Hong Kong, the impact of incorrect allergy labels in the geriatric patients (as well as other susceptible patient populations – such as immunocompromised and other patients with immunodeficiencies) warrants further investigation. Moreover, Hong Kong has a severely limited number of allergists with one of the lowest allergist-to-population ratios in the world. Given the long duration required to train and fulfil the demand of allergists in Hong Kong, novel and creative solutions to tackle the overwhelming burden of penicillin allergy are urgently needed. Multi-disciplinary collaborations between allied health staff and non-allergist are an attractive potential strategy. The impact of such multi-disciplinary initiatives for penicillin allergy delabelling would be enormous and should be urgently explored. In order to tackle the above limitations, this thesis documents a series of studies which were performed to investigate: (A) the epidemiology and unique aspects of beta-lactam antibiotics/penicillin allergy labels vs. genuine allergy, (B) the prevalence and impact of penicillin allergy labels among special populations, and (C) the prospective outcomes and future strategies of penicillin allergy delabelling in Hong Kong.