Comparative Effectiveness, Safety, and Real-World Outcomes of a Nurse-Led, Protocol-Driven Penicillin Allergy Evaluation From the Hong Kong Drug Allergy Delabelling Initiative (HK-DADI)

Labelling patients as allergic to beta-lactam antibiotics is associated with periprosthetic joint infection up to five years following knee arthroplasty

Aims

Periprosthetic joint infections (PJIs) represent a significant complication of total knee arthroplasty (TKAs). However, the influence of drug or beta-lactam (BL) antibiotic allergy labelling of patients on PJI remains largely unknown. In this study, we examine the association between patients labelled with a BL allergy and the occurrence of PJI among patients undergoing TKA. We also assess the prevalence of incorrect patient labelling and explore the feasibility of a multidisciplinary drug allergy testing initiative to detect mislabelling.

Methods

Longitudinal data from all patients who underwent TKA between January 1993 and December 2021 were analyzed. We investigated the association between different risk factors and PJI, with particular focus on patients labelled as having an antibiotic drug allergy. The outcomes of patients with and without a labelled BL allergy were compared. Additionally, patients labelled as having a BL allergy and who had undergone or were scheduled for TKA were prospectively investigated by formal allergy assessment.

Results

Out of 4,730 TKAs, the overall incidence of PJI was 1.0% (47/4,730). Patients labelled as having a BL allergy had a higher incidence of PJI within the first five years post-TKA compared to those without (3.0% (5/165) vs 0.7% (34/4,565); p = 0.001). The presence of a BL allergy label was identified as an independent risk factor for PJI (hazard ratio 4.86 (95% CI 2.05 to 11.53); p < 0.001). Following negative drug provocation testing, the majority of patients (95% (21/22)) evaluated with BL allergy labels were successfully delabelled.

Conclusion

In this longitudinal study, patients labelled as having a BL allergy were associated with having increased risk of PJI following TKA, particularly within the first five years. Given the high rate of patients being mislabelled, we recommend that patients labelled as having a BL allergy should be prioritized for formal allergy assessment and evaluation. Further studies on the impact of preoperative antibiotic allergy delabelling initiatives should be encouraged.

Leveraging COVID-19 vaccine allergy evaluations with coincident drug allergy delabelling: Effectiveness and impact on quality of life

BACKGROUND

Concerns of potential drug/vaccine-associated allergies significantly impact vaccine safety and hesitancy. Delabelling of incorrect drug allergy in the general public was previously impeded by limited access to allergist services, especially among less frequent healthcare utilisers in the community. COVID-19 vaccine allergy evaluation services have enabled individuals (mis)labelled with allergies to receive vaccinations safely and have provided opportunities to expand drug allergy delabeling access. We investigated the effectiveness of this coincident drug allergy delabelling and its impact on health-related quality of life (HRQoL).

METHODS

We recruited individuals labelled with drug allergies attending for COVID-19 vaccine evaluation in Hong Kong between 2021 and 2022. Demographics, comorbidities, drug allergy labels, COVID-19 vaccination and infection outcomes, as well as coincident delabelling rates were analysed. HRQoL was measured before and after evaluation in a subgroup of individuals.

RESULTS

Among 652 individuals, 1456 drug allergy labels were identified, with anti-infectives being the most common (606, 41.6 %). Beta-lactam antibiotics accounted for 55.1 % (334). Almost all individuals (99.4 %) safely proceeded with COVID-19 vaccinations, with an increased number of doses conferring better protection. 228 (35.0 %) individuals underwent drug allergy investigations, with coincident drug allergy delabelling successful in 223 (97.8 %), removing 317 (21.8 %) incorrect labels, of which 173 (51.8 %) were beta-lactams. Subgroup analysis showed improved serial health-related quality of life following delabelling (DrHy-Q 45.0 vs 33.3, p < 0.001).

CONCLUSION

Services evaluating COVID-19 vaccine allergies have not only empowered individuals labelled with drug allergy to receive vaccinations safely, but have also enhanced access to drug allergy delabeling services for the general public.

Prolonged versus single dose in penicillin oral challenge testing: protocols for a pilot and definitive randomised controlled trial (PROSPECTOR studies)

INTRODUCTION

Penicillin allergy labels (PALs) are reported in 1 in 10 hospitalised patients globally and associated with inferior patient, hospital and microbiological outcomes; however, the majority are incorrect and should be removed. Direct oral penicillin challenge has been demonstrated to be a safe and effective method for the removal of PALs. However, the question of whether a single dose is sufficient to ascertain true allergy status remains unanswered, with some studies suggesting that extended challenges of 3 or more days are superior for the exclusion of delayed immune reactions. The aim of the PROSPECTOR studies was to determine the feasibility (PROSPECTOR-1) of a definitive trial (PROSPECTOR-2) to evaluate the safety and effectiveness of prolonged oral challenge (ie, 5 days) versus single-dose oral challenge in patients with a delayed or unknown penicillin allergy phenotype (PROSPECTOR-2).

METHODS AND ANALYSIS

A pair of double-blind two-arm parallel placebo-controlled trials will be undertaken-PROlonged versus Single dose in PEnicillin oral Challenge Testing double-blind parallel group randomised placebo-cOntrolled tRial (PROSPECTOR Studies). Patients with a reported delayed or unknown timing penicillin allergy who have passed a supervised single-dose oral amoxicillin challenge (with or without prior skin testing/single or split dose) will be recruited. Informed patient consent will be granted for sites to recruit patients and collect routine clinical data. PROSPECTOR-1 will assess the safety and feasibility of a placebo-controlled trial for single-dose amoxicillin challenge versus 5-day prolonged oral challenge. PROSPECTOR-2 will assess the superiority of the 5-day prolonged oral challenge compared with single-dose amoxicillin challenge in excluding a delayed immune reaction. PROSPECTOR-2 will commence immediately post completion of PROSPECTOR-1 in a vanguard design, with adjustments to the projected sample size for superiority made following completion of PROSPECTOR-1. PROSPECTOR-2 will commence recruitment immediately following closure of PROSPECTOR-1; however, data from each trial will be analysed separately.

ETHICS AND DISSEMINATION

These studies were reviewed and approved by the Austin Health Human Research Ethics Committee (PROSPECTOR-1: HREC/99740/Austin-2023 and PROSPECTOR-2: HREC/109785/Austin-2024). The results will be published in peer-reviewed journals and presented at relevant conferences.

TRIAL REGISTRATION NUMBER

PROSPECTOR-1: ACTRN12623001242617 and PROSPECTOR-2: ACTRN12624001107516.

Impact of a drug allergy education course for non-specialists: Findings from ADAPT-A randomized crossover trial

BACKGROUND

The consequences of drug allergy remain a global health concern. Drug allergy is often a neglected topic and many non-specialists lack sufficient knowledge or confidence in evaluating or managing this common condition. Evidence-based interventions to better equip non-specialists to tackle drug allergy are needed. The aim of the study is to evaluate the effectiveness of an intensive educational course on drug allergy knowledge and practice of non-specialists.

METHODS

A randomized crossover trial (NCT06399601) was conducted among practicing physicians and nurses participating in an intensive drug allergy course-Advances in Drug Allergy & Penicillin Testing (ADAPT). Participants' baseline knowledge and self-reported practices were assessed with standardized questionnaires (scored from 0 to 100, with "satisfactory" defined as ≥60/100). Participants were randomized into two cohorts and attended ADAPT at different time points. Serial responses before and after the course were compared within and between cohorts.

RESULTS

Seventy participants (25 physicians, 45 nurses) randomized into two groups completed the course. Baseline drug allergy knowledge (58.0 ± 19.9) and self-reported practice (36.9 ± 24.3) were unsatisfactory among non-specialists, with significantly lower scores from nurses than physicians in both domains (knowledge: 49.0 ± 17.4 vs. 74.0 ± 12.7; practice: 32.1 ± 21.3 vs. 53.3 ± 23.1; all p < 0.001). Following completion of ADAPT, participants demonstrated significant improvements in knowledge (58.0 ± 19.9 vs. 77.7 ± 15.9, p < 0.001) and self-reported practice (36.9 ± 24.3 vs. 71.0 ± 20.2, p < 0.001). All participants (100%) and 99% of participants agreed that the course improved their clinical knowledge and practice, respectively.

CONCLUSIONS

ADAPT, an intensive drug allergy educational course was effective in improving drug allergy knowledge and practice for non-specialists. Further longitudinal studies are required to evaluate long-term impact.

NSAID Allergy Labels Associated With Mortality and Cardiovascular Outcomes in Stroke

BACKGROUND

Mislabeled drug allergy can restrict future prescriptions and medication use, but its prevalence and impact among patients with stroke remain unknown. This study investigated the prevalence of the most commonly labeled drug allergies, their accuracy, and their impact among patients with stroke.

METHODS

In this combined longitudinal and cross-sectional study, we compared the prevalence of allergy labels among the general population and patients with ischemic stroke between 2008 and 2014 from electronic health care records in Hong Kong. Outcomes between patients with stroke with or without the most prevalent labels (ie, NSAID) were compared. Rate of mislabeled NSAID allergy was confirmed by provocation testing.

RESULTS

Compared with the general population (n=702 966), patients with stroke had more labels (n=235) to cardiovascular and hematopoietic system (prevalence, 19.5% versus 9.2%; odds ratio [OR], 2.4 [95% CI, 1.74-3.32]; P<0.001) and radiographic and diagnostic agents (prevalence, 4.2% versus 0.9%; OR, 4.82 [95% CI, 2.56-9.08]; P<0.001). The most common labels were to NSAID (prevalence, 1.8%). Patients with NSAID allergy labels were significantly less likely to be prescribed aspirin after acute stroke (OR, 0.24 [95% CI, 0.09-0.60]; P=0.003) and on follow-up (OR, 0.22 [95% CI, 0.08-0.56]; P=0.002). The median duration of follow-up was 6.7 years (6499±2.49 patient-years). Patients with stroke with NSAID allergy labels also experienced significantly higher mortality (OR, 7.44 [95% CI, 2.44-23.18]; P<0.001), peripheral vascular disease (OR, 9.35 [95% CI, 1.95-44.86]; P=0.005), and major adverse cardiovascular events (OR, 6.09 [95% CI, 2.00-18.58]; P=0.001) in the poststroke period. Patients with NSAID allergy labels (who remained alive and could consent) were referred for allergist assessment and offered drug provocation testing. The majority (80%; 4/5) had negative provocation tests and were delabeled.

CONCLUSIONS

NSAID allergy labels were significantly more prevalent among patients with stroke, associated with excessive mortality, peripheral vascular disease, and major adverse cardiovascular events. Given the high rate of mislabeled allergies, multidisciplinary neuro-allergy interventions could have the potential to improve patient outcomes.

Comparing pharmacists versus allergists in low-risk penicillin allergy delabelling: The Hong Kong Penicillin Allergy Pharmacist Initiative (HK-PAPI)

Background

Mislabelled penicillin allergies are associated with a myriad of adverse outcomes and development of anti-microbial resistance. With the overwhelming need for specialist allergy services, pharmacist initiatives such as the Hong Kong Penicillin Allergy Pharmacist Initiative (HK-PAPI) have been advocated. However, evidence of their effectiveness, safety and impact on health-related quality-of-life (HR-QoL) are lacking.To assess and compare the effectiveness, safety and improvements on HR-QoL of pharmacists vs allergists in a pilot low-risk penicillin allergy delabelling initiative.

Methods

All adult patients referred for low-risk penicillin allergy were randomized and evaluated by either pharmacists or allergists in a 1:3 ratio. Outcomes and changes in Drug Hypersensitivity Quality of Life Questionnaire (DrHy-Q) scores were compared.

Results

Of 323 patients referred, 96.3% (311/323) completed penicillin allergy evaluation (pharmacists: 83 [24.3%] vs allergists: 228 [66.7%]). Overall, 93.6% (291/311) were delabelled with no difference between evaluations by pharmacists and allergists (92.8% vs 93.9%, p = 0.729). There were no severe or systemic reactions in either cohort. Patients evaluated by either pharmacists (43.4 [SD:29.1] to 10.5 [SD:5.93], p < 0.001) or allergists (37.2 [SD:22.2] to 29.1 [SD:22.4], p < 0.001) reported improved HR-QoL as reflected by DrHy-Q scores. However, absolute changes in DrHy-Q scores were significantly greater among patients evaluated by pharmacists compared to those by allergists (-24.6 [SD:25.1] vs -9.19 [SD:13.7], p < 0.001).

Conclusions

Evaluations and delabelling by pharmacists (vs allergists) were comparably effective and safe among patients with low-risk penicillin allergy. Moreover, patients evaluated by pharmacists even reported significantly greater improvements in HR-QoL, highlighting the potential of multidisciplinary allergy initiatives.

Evaluation of patients labeled with a penicillin allergy to promote antimicrobial stewardship in dental practice

BACKGROUND

Approximately 10% of the US population self-reports a penicillin allergy history or are labeled as penicillin allergic. However, from 90% through 99% of these patients are not allergic on formal evaluation.

CASE DESCRIPTION

Patients labeled as penicillin allergic receive broader-spectrum and sometimes less-effective antibiotics, thereby contributing to increased treatment failures, antibiotic resistance, and adverse drug reactions. Self-reported penicillin allergy can be eliminated or classified as low-, medium-, or high-risk after a careful review of patient history. This allows these patients to be delabeled; that is, having any reference to their penicillin allergy history or of having an allergy to penicillin eliminated from their health records.

PRACTICAL IMPLICATIONS

Oral health care professionals are ideally placed to partner in both antibiotic stewardship interventions by means of recognizing pervasive mislabeling and aiding in the process of delabeling.

Prospective, Multicenter, Head-to-Head Comparison Between Allergists Versus Nonallergists in Low-Risk Penicillin Allergy Delabeling: Effectiveness, Safety, and Quality of Life (HK-DADI2)

BACKGROUND

Penicillin "allergy" labels are prevalent but frequently misdiagnosed. Mislabelled allergies are associated with adverse outcomes and increased antimicrobial resistance. With an urgent need to delabel the overwhelming number of mislabeled allergies, nonallergist evaluations have been advocated for low-risk individuals. Despite growing interest in non-allergist-led initiatives, evidence on their effectiveness, safety, and impact by direct comparisons is lacking.

OBJECTIVE

To assess the comparative outcomes of penicillin allergy evaluations conducted by allergists versus nonallergists.

METHODS

A prospective, multicenter, pragmatic study was conducted at 4 tertiary hospitals (1 allergist- vs 3 non-allergist-led) for low-risk penicillin allergy patients in Hong Kong-the Hong Kong Drug Allergy Delabelling Initiative 2 (HK-DADI2).

RESULTS

Among 228 low-risk patients who underwent testing (32.9% by allergists, 67.1% by nonallergists), only 14 (6.1%) had positive penicillin allergy testing results. Delabeling rates (94.1% vs 93.3%; P = .777), positive skin test results (2.6% vs 2.7%; P > .99), and drug provocation test results (3.3% vs 2.7%; P = 1.000) were similar between allergists and nonallergists. There were no systemic reactions in either cohort. All patients had significant improvements in health-related quality of life (Drug Hypersensitivity Quality of Life Questionnaire scores -5.00 vs -8.33; P = .072). Nonallergist evaluations had shorter waiting times (0.57 vs 15.7 months; P < .001), whereas allergists required fewer consultations with higher rate of completing evaluations within a single visit (odds ratio, 0.04; P < .001).

CONCLUSIONS

With training and support, nonallergists can independently evaluate low-risk penicillin allergies. Compared with allergists, evaluation of low-risk penicillin allergy by nonallergists can be comparably effective, safe, and impactful on quality of life. More multidisciplinary partnerships to empower nonallergists to conduct allergy evaluations should be encouraged.

Enhancing Patient-Reported Outcome Measures for Drug Hypersensitivity: A Validated 6-Item Quality-of-Life Questionnaire for Patients With Drug Hypersensitivity

BACKGROUND

Drug hypersensitivity reactions (DHRs) can significantly impair patients' health-related quality of life (HRQoL). However, tools for HRQoL assessment for patients with DHR are time-consuming and remain underutilized.

OBJECTIVE

To develop and validate an optimized version of the Drug Hypersensitivity Quality-of-Life Questionnaire (DrHy-Q) designed for everyday clinical use.

METHODS

Item response theory (IRT), a statistical framework for psychometric measurement, was used to evaluate the 15 questions from the original DrHy-Q for their respective item difficulty, discrimination, and information using prospective data from 243 patients with histories of suspected/confirmed DHR before allergy workup. Accordingly, the best-performing items were identified to develop a 6-item optimized version (DrHy-Q6), which was subsequently validated with another prospective cohort of 156 patients.

RESULTS

All 15 items of the original DrHy-Q demonstrated satisfactory parameters in IRT analysis, including very high discrimination (>1.7), appropriate difficulty (in between -1.5 and 1.5), and good information (a high and broad peak in the information curve). Six items with top-ranked IRT parameters were identified to construct an optimized version, which we named the DrHy-Q6. The DrHy-Q6 demonstrated a 1-factor structure with an improved fit compared with the original DrHy-Q (comparative fit index = 0.985, Tucker-Lewis index = 0.974), excellent convergent validity (unadjusted Pearson correlation with the full version = 0.955; adjusted = 0.894, P < .001), reliability (Cronbach's α and McDonald's ω = 0.93), divergent validity (Pearson correlation with all Short Form 12-item Health Survey Version 2 subscales <0.60, P < .001), and discriminant validity (significantly higher scores with multiple DHR labels [42.45 ± 27.26 vs 32.93 ± 26.66], P = .013).

CONCLUSIONS

From an IRT perspective, the DrHy-Q and all its constituent items are psychometrically valid for HRQoL assessment. We propose an optimized 6-item version (DrHy-Q6) as an abbreviated alternative for assessing HRQoL in patients with DHR, especially for routine use in clinical practice. Patients and physicians may benefit from its streamlined length and simpler scoring algorithm.

Identifying the most at-risk age-group and longitudinal trends of drug allergy labeling amongst 7.3 million individuals in Hong Kong

BACKGROUND

Incorrect drug 'allergy' labels remain a global public health concern. Identifying regional trends of drug allergy labeling can guide appropriate public health interventions, but longitudinal or population drug allergy studies remain scarce. We analysed the serial epidemiology of drug allergy labeling to identify specific subgroups at highest risk of drug allergy labeling for potential interventions.

METHODS

Longitudinal, population-wide drug allergy labels and clinical data from over 7,337,778 individuals in Hong Kong between 2016 and 2021 were analysed.

RESULTS

The absolute prevalence and incidence of documented drug allergy were 5.61% and 277/100,000 population, respectively. Annual incidence of new allergy labels was stable between 2016 and 2019, until a significant drop in 2020 (-16.3%) during the COVID19 pandemic. The most common allergy labels were anti-infectives (245,832 [44.5%]), non-steroidal anti-inflammatory (106,843 [19.3%]), and nervous system drugs (45,802 [8.3%]). The most common labeled culprits for the most severe immediate-type (anaphylaxis) and non-immediate-type (Stevens-Johnson syndrome) reactions were beta-lactams and nervous system drugs, respectively. For individuals at highest risk of labeling, there was significantly higher incidence of overall drug and beta-lactam allergy labeling amongst individuals aged > 40 years which contributed to the majority of newly labeled allergies (377,004, 68.2%).

CONCLUSIONS

Contrary to traditional dogma, we identified disproportionately higher incidence of drug allergy labeling amongst older individuals, rather than the paediatric age group. We advocate for more population-wide drug allergy studies to investigate this phenomenon in other cohorts as well as future preventative and delabeling efforts focusing on the adult population.

Hong Kong-Macau Severe Hives and Angioedema Referral Pathway

Background

Urticaria (defined as the presence of hives, angioedema, or both) can be caused by a variety of etiologies ranging from more common conditions such as chronic spontaneous urticaria (CSU) to rarer conditions such as hereditary angioedema (HAE). Specialist referral may be necessary in cases of severe urticaria or HAE, but access to specialist services remains limited in certain regions, such as the Greater Bay Area (GBA) of China. To address this, the Hong Kong-Macau Severe Hives and Angioedema Referral Pathway (SHARP) was initiated by the Hong Kong Institute of Allergy and Macau Society of Dermatology to promote multidisciplinary collaboration and regional exchange of expertise in the diagnosis and management of severe urticaria.

Methods

A nominated task force of dermatologists and immunologists who manage patients with severe urticaria formulated the consensus statements (CS) using the Delphi method. The consensus was defined a priori as an agreement of ≥80%.

Results

A total of 24 CS were formulated, including four statements on classifications and definitions, seven statements on diagnosis, and 13 statements on management and referral. The definitions for acute/chronic urticaria and severe CSU were stated. Unnecessary investigations and inappropriate medications were discouraged. The characteristics and recommended approach to suspected bradykinergic angioedema were specified. Stepwise treatment options using second-generation antihistamines, omalizumab, or cyclosporin for patients with CSU were addressed, and the importance of access to HAE-specific medications was emphasized. Furthermore, an integrated referral pathway for patients with severe hives and angioedema was constructed.

Conclusion

The SHARP provides guidance for the management and specialist referral of patients with severe hives and angioedema in Hong Kong and Macau.

Epidemiology, outcomes, and disproportionate burden of food-dependent exercise-induced anaphylaxis from the Hong Kong Multidisciplinary Anaphylaxis Management Initiative (HK-MAMI)

Background

Anaphylaxis is a life-threatening allergic reaction that poses a considerable burden on populations across all ethnicities and age groups. The Hong Kong Multidisciplinary Anaphylaxis Management Initiative (HK-MAMI) was established to streamline the assessment of patients with anaphylaxis via a multidisciplinary and protocol-driven approach.

Objective

This prospective study aims to define the etiology, clinical manifestations, and treatment of patients with anaphylaxis in Hong Kong.

Methods

Prospective clinical data from allergologic investigations from patients who completed evaluation by the HK-MAMI pathway between January 2017 and August 2022 were analyzed.

Results

Of the 161 patients referred via the HK-MAMI, 131 (81.4%) met the diagnostic criteria for anaphylaxis. The median delay in diagnosis was 2 years (range 0-30 years). The majority of anaphylaxis cases were attributed to food-dependent exercise-induced anaphylaxis (FDEIA), especially wheat-dependent exercise-induced anaphylaxis. In acute management settings, paired tryptase samples were taken in only around one-third of anaphylaxis cases, with 82.5% of the samples demonstrating significant elevation. There was a general underprescription of adrenaline autoinjectors, especially for food-related anaphylaxis. Patients with FDEIA had later ages of onset and diagnosis, and they presented with more cardiovascular manifestations. Skin prick tests and specific IgE level tests were able to diagnose 95% of FDEIA cases.

Conclusion

Our study highlights the significant burden of FDEIA, and especially WDEIA, in Hong Kong, its association with severe presentations, and difficulties encountered in emergency or primary care settings. We advocate appropriate adrenaline use during acute-care management and discharge plans, as well as taking serum mast cell tryptase samples during acute episodes. Interdisciplinary collaboration remains crucial to upholding proper and optimized care for patients with anaphylaxis in Hong Kong.

Delabelling multiple antibiotic allergy: Practical issues

With the growing incidence of multi-drug resistant organisms, delabelling incorrect antibiotic allergies has become an integral part of antimicrobial stewardship worldwide. For example, around 90% of penicillin allergy labels are found to be inaccurate following a full allergy work-up, which deprive patients the use of effective first-line penicillin antibiotics and increase the risk of antimicrobial resistance with the use of other extended spectrum non-penicillin antimicrobials. Significant numbers of adult and paediatric patients over time are labelled with multiple penicillin and non-penicillin antibiotic allergies often during inappropriate antimicrobial use, resulting in a label of “multiple antibiotic allergy”. In contrast to delabelling penicillin allergy where oral direct provocation tests can be used for low-risk, mild reactions, and sensitivity/specificity/positive and negative predictive values of skin tests have been demonstrated, diagnostic tests for multiple antibiotic allergy often require the use of a combination of in-vivo and in-vitro tests across different antimicrobial classes for evaluation. Shared decision making with patients and informed consent are also needed when prioritising which drugs to delabel first, balancing the risks, benefits of testing vs. interim use of alternative antibiotics. Similar to delabelling penicillin allergy, the cost-effectiveness of delabelling multiple drug allergies is unknown.

A case of persistent IgE sensitisation almost two decades following ampicillin anaphylaxis

BACKGROUND

Although most immunoglobulin E (IgE)-mediated penicillin allergy wanes with time, sensitisation may occasionally persist for many years. Previous reports on the loss of penicillin-specific IgE sensitisation were based on non-anaphylaxis cases and, although uncommon, persistent sensitisation may still be possible in the minority of cases.

OBJECTIVE

This case highlights that irrespective of the elapsed duration since the index reaction, it is important to remain vigilant when approaching patients with a history of severe reactions.

MATERIAL AND METHODS

We described a case of persistent IgE sensitisation almost two decades following ampicillin anaphylaxis.

RESULTS

A 78-year-old male with a history of perioperative penicillin anaphylaxis in 2003 was referred for allergy workup in 2022 before his knee joint replacement surgery. The patient had strictly avoided all beta-lactams since the index reaction. However, his penicillin-specific sensitisation persisted, evidenced by positive skin tests (with generalised urticaria after intradermal testing) and basophil activation tests.

CONCLUSION

To our knowledge, this was the first case of positive BAT tested around two decades following the index reaction. This case illustrates that a cautious approach may still be warranted in patients with a history of severe reaction to penicillin regardless of the duration since the reported index reaction.

Differences in beta-lactam and penicillin allergy: Beyond the West and focusing on Asia-Pacific

Beta-lactam (BL) antibiotic "allergy" labels are common, but often overdiagnosed. Although much research has been focused on the BL allergy and the delabelling process in the West, studies from other parts of the world remain sparse. This review outlines the contrasting global epidemiology, shifting clinical practices and disparities of BL allergy in the Asia-Pacific region compared with the West. Innovative strategies to overcome barriers in BL allergy workup are discussed and potential directions for future research and service development are also proposed.