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Pedro Simão Coelho1, Gonçalo Martins dos Santos1, Mila Mikovic1, João Oliveira2, Sónia Rosa1, Paula Leiria Pinto1, Eduardo Silva2

1 - Serviço de Imunoalergologia, Centro Hospitalar Universitário de Lisboa Central
2 - Serviço de Medicina Interna 2.3, Centro Hospitalar Universitário de Lisboa Central

- EAACI Hybrid Congress 2022

BACKGROUND. Drug hypersensitivity reactions (DHR) are frequently self-reported by patients, but are usually mistaken for predictable adverse drug reactions, infectious manifestations, or other conditions. The majority are not confirmed after a careful evaluation; however, this is seldom done, leading to both overdiagnosis of drug allergy and undervaluation due to lack of confirmation. This study intends to evaluate the consequences of devaluing a self-reported diagnosis of drug allergy.
METHODS. Retrospective study conducted in an Internal Medicine ward from a tertiary hospital in Lisbon, Portugal. All patients admitted between January 2018 and December 2020 with a drug allergy report on their electronic medical records were included. Data was collected from electronic medical records.
RESULTS. Of a total of 3046 patients, 470 (15%) were selected due to their reported allergy history. The suspected drug was administered on 15% (n=69) of patients: 54 (78%) antibiotics, 7 (10%) non-steroid anti-inflammatory drugs, 2 (3%) radiocontrast media (RCM), 2 (3%) bronchodilators, and 4 (6%) other drugs. A clear medical history of past events was present in 49% (n=34) of these patients, with 29 reporting immediate symptoms (minutes to hours) and 5 describing late reactions (days). A total of 12 (17%) patients had previously received the suspected drug in the hospital setting, 11 (92%) tolerated the drug and 1 (8%) had a mucocutaneous reaction description, all of which were reproducible. After administration of the suspected drug, 87% (n=60) of the patients presented no reaction and 13% (n=9) developed a reaction assumed by the attending physician as an allergic reaction, one of which an anaphylaxis. Six (67%) patients presented similar reactions as previously described. The other 3 (33%) patients, either had a different timing reaction or no previous report to compare with. None was referred to our Allergy and Clinical Immunology Department.
CONCLUSION. A self-report of a drug allergy may be real and devaluing such history can be associated with avoidable life-threating reactions. Past medical records are fundamental to help distinguish between a possible and a less probable allergy. An evaluation by an immunoallergy specialist should always be performed to confirm or exclude the diagnosis.

Palavras Chave: fármacos, hipersensibilidade