D2.245 - Long-Term Outcomes of Beta-Lactam Allergy De-Labelling: A Retrospective 10 year Analysis of Patient Confidence and Antibiotic Tolerance

Inaccurate beta-lactam allergy labels limit antibiotic options and contribute to broad-spectrum antibiotic overuse,  increasing prevalence of multi-drug-resistant organisms. De-labelling suspected beta-lactam allergies improves patient outcomes and supports appropriate antibiotic use. However, its long-term success depends on patient confidence in safely using beta-lactams. Our objective was to evaluate long-term outcomes of patients de-labelled from beta-lactam allergy.

We retrospectively analysed medical records for 195 adult patients who underwent beta-lactam de-labelling between 2015 and 2024. Patients underwent skin and drug provocation tests at a tertiary hospital Drug Allergy clinic. Data collected included patient demographics, initial reaction age and type, comorbidities, PEN-FAST scores and specific IgE (sIgE) levels. We also assessed post-de-labelling variables such as subsequent beta-lactam use and reported tolerance.

Of the patients analysed, 73.8% were female and 26.2% male, with a median age of 50 years (range: 18-87) at de-labelling. Common comorbidities included rhinitis (22.6%), asthma (12.8%), and chronic urticaria (10.3%). 59 (30.3%) patients reported childhood reactions, while the remaining adult-onset reactions had a median age of 40 years (range: 18-80). Immediate reactions accounted for 40.5%, of which 39.2% were non-specific/vasovagal and 16.5% reported anaphylaxis. 116 (59.5%) were delayed, of which exanthema was the most frequently reported (58.6%). Of 37 patients (18.9%) with co-existing drug allergies, 56.8% were NSAID-related. PEN-FAST scores indicated low risk in 84.1% of patients; sIgE was positive in one case. 127 (65.1%) patients used beta-lactams post-de-labelling, out of which 49.6% took the culprit drug. No adverse reactions were reported among patients who received beta-lactams.

Our findings highlight the efficacy of beta-lactam allergy de-labelling, with most patients safely tolerating beta-lactams. A subset of patients did not receive beta-lactams post-de-labelling, highlighting the need for further follow-up to assess patient and physician confidence. Limitations include reliance on medical records rather than patient-reported outcomes, and variable follow-up durations. Despite this, our study provides valuable insights into post-de-labelling antibiotic use and areas for improving patient confidence.