1 - Allergy and Clinical Immunology Department, Hospital de Dona Estefânia, Centro Hospitalar de Lisboa Central, E.P.E., Rua Jacinta Marto, Lisbon, Portugal
2 - CEDOC, Integrated Pathophysiological Mechanisms Research Group, Nova Medical School, Campo dos Mártires da Pátria, 1150-190 Lisbon, Portugal
- EAACI- Congresso da European Academy of Allergy and Clinical Immunology- Lisboa , sob a forma de poster , 1 a 5 Junho 2019
Background: Most referrals of suspected antibiotic allergy with non-immediate hypersensitivity reactions (NIHSR) in children are due to beta-lactams (BL).
Drug provocation tests (DPTs) are the gold-standard method to rule out this important diagnosis, but standardization of DPTs is required. The optimal duration of the drug intake is still unestablished, and protocols range from one to several days. Our study’s purpose was to compare the BL re-exposure rate after a DPT using two different protocols (one-day, or short protocol, versus 3-7 days, extended protocol), in diagnosing NIHSR with BL in children followed at our outpatient clinic.
Method: Using a questionnaire performed after a negative DPT with a BL, we analyzed the frequency of re-exposure rate to the tested drug according to the two protocols: short (one-day) and extended (3-7 days) DPTs.
Results: Sixty-one patients were included (38 were males). The median age at the time of the reaction was 3 years (P25-P75: 1-4 years) and age at the time of the DPT was 4 years (P25-P75: 2-6 years). All the reactions were mucocutaneous. The implicated drugs in the reaction were: amoxicillin in 31 patients, amoxicillin-clavulanate in 27 children, and cephalosporins for the remaining three. Thirty-four (57%) children performed a short DPT and 27 an extended DPT. The time delay between the reaction and the DPT was slightly higher for those that underwent an extended DPT (p-value=0.023). Thirty-six (59%) children were re-exposed to BL months to years after the negative DPT. Children that performed a short DPT presented a higher re-exposure rate than the ones that performed an extended protocol (71% versus 44%, p-value=0.039).
Conclusion: An important proportion of the children that underwent a DPT did not take any BL after the test, particularly those that performed an extended protocol. The reasons are unclear but psychological factors like resistance in accepting new provided evidence that conflicts with personal beliefs and the consequential increase of the last ones, may have contributed.