• Philip H Li, Heather H F Yeung, Chak-Sing Lau, and Elaine Y L Au.
• Division of Rheumatology and Clinical Immunology, Department of Medicine, Queen Mary Hospital, Hong Kong.
• JAMA Netw Open. 2020 May 1; 3 (5): e204199.

ImportanceAllergy to β-lactam antibiotics is one of the most frequently reported drug reactions, but epidemiological data in Chinese populations are lacking. Ethnic- and region-specific sensitization patterns of skin testing for β-lactam antibiotic allergy are also unknown.ObjectiveTo identify the prevalence, 1-year incidence, and sensitization patterns of β-lactam antibiotic allergy in patients in Hong Kong.Design, Setting, And ParticipantsThis cross-sectional study obtained territorywide, anonymized electronic patient data from the Clinical Management Systems of the Hospital Authority, the sole publicly funded health care system in Hong Kong with facilities in 7 regions (Hong Kong East, Hong Kong West, Kowloon Central, Kowloon East, Kowloon West, New Territories East, and New Territories West). All referrals to Queen Mary Hospital for β-lactam antibiotic allergy testing from January 1, 2018, to December 31, 2019, were also analyzed for sensitization patterns.Main Outcomes And MeasuresPrevalence and cumulative incidence of β-lactam antibiotic allergy reported in Hong Kong, and sensitization patterns according to β-lactam antibiotic allergy skin testing.ResultsComplete records of 7 184 271 unique patients were analyzed, with a men to women ratio of 1:1.2 and with a median age of 44 years. The prevalence of physician-reported β-lactam antibiotic allergy was 2.0%, and the cumulative incidence was 107 per 100 000 population. Of the 34 402 new drug allergies reported in 2018, 8032 (23.3%) were β-lactam antibiotic allergies. Three hundred fifty-five patients with reactions suggestive of β-lactam antibiotic allergy underwent skin testing, and only 49 (13.8%; 95% CI, 10.64%-17.90%) of them had positive test results. Of these 49 patients, 14 (28.6%; 95% CI, 18.35%-44.49%) had selective reaction and 35 (71.4%; 95% CI, 59.84%-85.27%) had nonselective reaction. The sensitization rate to either benzylpenicilloyl polylysine or a minor determinant (benzylpenicilloate) was 47.0% (n = 23; 95% CI, 34.85%-63.21%), with 10 patients monosensitized to benzylpenicilloyl polylysine only (20.4%; 95% CI, 11.74%-35.48%) and 5 to benzylpenicilloate only (10.2%; 95% CI, 4.45%-23.42%).Conclusions And RelevanceResults of this study suggest that patients in Hong Kong with β-lactam antibiotic allergy had much higher rates of monosensitization to benzylpenicilloyl polylysine and benzylpenicilloate, making these reagents essential in β-lactam antibiotic skin tests. Such a finding warrants future studies into whether this sensitization is specific to ethnicity or region.

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