BACKGROUND: The frequency of cefaclor-induced immediate hypersensitivity reactions has increased in Korea. Skin prick test (SPT) and intradermal test (IDT) using cephalosporins are not as well validated as those using penicillin. Limited data are available regarding the diagnostic value of SPT and IDT for cefaclor-induced immediate hypersensitivity reactions. OBJECTIVE: To compare the clinical utility of the SPT and IDT with that of the ImmunoCAP test in patients with cefaclor-induced immediate hypersensitivity reactions. METHODS: We conducted a retrospective analysis of participants from a tertiary hospital in Korea with a history of suspected immediate hypersensitivity reaction to cefaclor who had undergone SPT, IDT, and ImmunoCAP. RESULTS: A total of 155 patients diagnosed with cefaclor-induced immediate hypersensitivity reactions were included in the analysis. Eighty-one patients tested positive for both the SPT/IDT and the ImmunoCAP test. Sixty patients were positive for the SPT/IDT but negative for the ImmunoCAP test. Seven patients tested positive only for the ImmunoCAP test. SPT/IDT positivity and SPT positivity were significantly higher in cases of anaphylaxis compared to urticaria
however, ImmunoCAP positivity did not differ based on the reaction severity. CONCLUSIONS: SPT/IDT are more sensitive than ImmunoCAP for diagnosing cefaclor-induced immediate hypersensitivity reactions, particularly in cases of anaphylaxis. The positivity of SPT/IDT varies depending on the severity of the hypersensitivity reaction. Therefore, SPT/IDT should be considered for diagnosing cefaclor-induced anaphylaxis.