Allergy clinic patients' drug hypersensitivity

Background: Drug hypersensitivity reaction (DHR) is a common reason for an allergology consultation, during which it is not only necessary to gather a thorough medical history, but also to propose and perform diagnostic tests. Objectives: The aim of the study was to retrospectively assess the patients with a profile of preliminary drug hypersensitivity diagnosis, the usefulness of NSAID hypersensitivity classification in outpatient practice, and to analyze the results of skin, provocation, and drug tolerance tests performed in Immunology and Allergy Clinic patients. Methods: Around 501 medical records of patients referred to the academic allergy outpatient clinic from 2011 to 2019, and had a preliminary drug hypersensitivity diagnosis were analyzed. The diagnostic and drug tolerance tests results carried out in 269 patients of the Clinic from 2009 to 2019 were then evaluated. Results: Among the patients referred due to suspected drug hypersensitivity, the majority (n=338, 67.5%) were believed to be hypersensitive to NSAIDs and antibiotics (n=272, 54.3%). In patients with hypersensitivity to NSAIDs, the mixed pattern was the most prevalent (n=73, 21.6%), followed by NECD (n=64, 18.9%) and NIUA (n=55, 16.3%). The second most common drug causing DHR were the antibiotics, mainly beta-lactams (n=160, 58.8%), followed by macrolides (n=35, 12.9%). In hypersensitivity caused due to beta-lactams, the delayed form was predominant (n=24, 15%) with manifested skin symptoms (n=74, 46.3%). Non-steroidal anti-inflammatory drugs (n=21, 42.9%), followed by antibiotics (n=11, 22.5%) were the commonest causes of anaphylaxis, as reported by 49 patients. Conclusion: The study shows that a majority of patients with suspected drug hypersensitivity can be classified under the hypersensitivity umbrella based on their medical history, which is the basis for further diagnostic process.