Extending the role of tryptase in perioperative anaphylaxis: Predicting positive results in basophil activation tests.

Background: Basophil activation tests (BATs) are useful in identifying culprits of perioperative anaphylaxis (PA), but their utility remains limited due to technical limitations, cost, and availability. Being able to prioritize patients with likely higher yields for BAT would be useful in reducing costs and manpower. Objective: We sought to investigate whether tryptase levels and clinical parameters may be useful for selecting patients for BATs. Methods: We performed a 10-year retrospective study in Hong Kong to investigate the performance of BATs associated with tryptase levels (taking during PA) and other clinical parameters. Results: Of 90 patients, 70 (77.8%) showed significant tryptase level elevation and 37 (41.1%) had a positive BAT result. BAT-positive patients presented with significantly higher absolute levels (15.9 µg/L vs 9.1 µg/L; P = .018), absolute elevation (12.8 µg/L vs 7.1 µg/L; P = .012), and fold elevation (5.6- vs 4.1-fold; P = .014) of acute tryptase than did BAT-negative patients. Among patients with positive BAT result, 94.6% (35 of 37) demonstrated elevated acute tryptase, significantly more than the BAT-negative group (66.0%; P < .001). In regression analysis, tryptase elevation was the sole significant factor correlated to BAT positivity (odds ratio, 10.14; 95% CI, 2.15-47.85; P = .003). Overall, elevated acute tryptase demonstrated a sensitivity of 94.7% and a negative predictive value of 90.0% in predicting positive results with BATs. Conclusions: We observed that tryptase elevation is a very sensitive predictor of BAT positivity among patients with identified culprits of PA. Acute elevation of tryptase would not only aid in confirming anaphylaxis but may also help guide the decision toward selecting labor-intensive and costly in vitro tests such as BATs.

Ten-year outcomes of Perioperative Anaphylaxis Workup Study in Hong Kong (PAWS-HK): Performance of diagnostic modalities.

BACKGROUND: Studies on perioperative anaphylaxis (PA) in Asia are lacking. Furthermore, allergy workup for PA has largely been limited to the "silver standard" of skin tests (ST). Using in vitro tests as an adjunct to ST may improve and overcome these diagnostic challenges. OBJECTIVE: To evaluate the clinical characteristics and diagnostic tests of patients with suspected PA through the Perioperative Anaphylaxis Workup Study in Hong Kong cohort. METHODS: Patients with a diagnosis of PA over a 10-year period were recruited into the Perioperative Anaphylaxis Workup Study in Hong Kong. We reviewed the medical records, tryptase elevation, and diagnostic tests including ST, specific immunoglobulin E, and basophil activation tests (BAT). RESULTS: In 151 patients with PA, diagnosis was reached in three-fourths of the cases (113/151, 74.8%). The most common culprits identified were neuromuscular blocking agents (25.8%), ß lactams (17.2%) and chlorhexidine (13.9%). Severe anaphylaxis was associated with female sex, older age, elevated acute tryptase levels, and more cardiovascular manifestations during induction. Skin tests remained the most sensitive diagnostic modality overall (66.2%). BAT showed better performance for chlorhexidine and gelofusine anaphylaxis, with sensitivity of 80.0% and 79.6%, respectively. Specific Immunoglobulin E indicated even higher sensitivity (95.2%) than did ST (85.0%) and BAT (80.0%) for chlorhexidine anaphylaxis but performed poorly for other drugs. CONCLUSION: Neuromuscular blocking agents remain the most common culprit in PA. There was a higher prevalence of gelofusine anaphylaxis in our cohort than was seen in the literature. Skin tests remain the most sensitive testing modality. In vitro tests for chlorhexidine and gelofusine showed promising results, but more studies to further elucidate its use are warranted.

Prevalence, Incidence, and Sensitization Profile of ß-lactam Antibiotic Allergy in Hong Kong.

Importance: Allergy to ß-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 ß-lactam antibiotic allergy are also unknown. Objective: To identify the prevalence, 1-year incidence, and sensitization patterns of ß-lactam antibiotic allergy in patients in Hong Kong. Design, Setting, and Participants: This 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 ß-lactam antibiotic allergy testing from January 1, 2018, to December 31, 2019, were also analyzed for sensitization patterns. Main Outcomes and Measures: Prevalence and cumulative incidence of ß-lactam antibiotic allergy reported in Hong Kong, and sensitization patterns according to ß-lactam antibiotic allergy skin testing. Results: Complete 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 ß-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 ß-lactam antibiotic allergies. Three hundred fifty-five patients with reactions suggestive of ß-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 Relevance: Results of this study suggest that patients in Hong Kong with ß-lactam antibiotic allergy had much higher rates of monosensitization to benzylpenicilloyl polylysine and benzylpenicilloate, making these reagents essential in ß-lactam antibiotic skin tests. Such a finding warrants future studies into whether this sensitization is specific to ethnicity or region.