Clinical Significance of the Skin Test for the Diagnosis of Ranitidine-induced Immediate Hypersensitivity Reaction

Ranitidine is often known to cause an immediate hypersensitivity reaction. The aim of this study is to evaluate the clinical significance of skin tests with ranitidine. We retrospectively reviewed the medical records of 52 patients who underwent skin tests with ranitidine for immediate hypersensitivity reactions at Chonnam National University Hospital from 2016 to 2019. A skin prick test (SPT) was performed at a concentration of 25 mg/mL, and if the SPT was negative, intradermal tests (IDT) were performed sequentially at 0.25 mg/mL, 2.5 mg/mL, and 25 mg/mL. Out of 52 patients, 29 were positive for SPT; for IDTs, 9 were positive at 0.25 mg/mL, 10 were positive at 2.5 mg/mL, 3 were positive at 25 mg/mL, and 1 patient was negative for all concentrations. We analyzed 36 patients who were determined whether or not ranitidine is a causative drug by the drug provocation test or clinically, and the area under the ROC curve for SPT with IDT at a concentration of 0.25 mg/mL was 0.78, and was larger than for the SPT alone or the IDT at a higher concentration. Furthermore, it showed 90% sensitivity, 67% specificity, 93% PPV, and 57% NPV. A SPT at a concentration of 25 mg/mL with an IDT at a concentration of 0.25 mg/mL is considered the best skin test method for the diagnosis of ranitidine-induced immediate hypersensitivity reaction. If the IDT is positive at a higher concentration than 0.25 mg/mL or the medical history is ambiguous, a drug provocation test should be performed.