Adverse reactions during drug challenges: A single US institution's experience

Background: Drug challenge is a useful tool when diagnostic testing lacks predictive value for a questionable history of drug allergy. Placebo-controlled drug challenge studies demonstrate that a significant number of patients report purely subjective symptoms to placebo. Objective: To evaluate the safety and rate of adverse effects when performing drug challenges and to identify predictive factors for occurrences of subjective symptoms during drug challenges. Methods: We performed a 6-year, retrospective medical record review of patients who underwent drug challenges by members of the Allergy and Immunology Division after consultation deemed drug challenges to be appropriate. Statistical analysis was performed to compare the proportion of patients with subjective symptoms based on certain factors, including sex, age, number of listed drug allergies, interval from historical drug reaction to the drug challenge, and types of historical reaction. Results: A total of 114 patients underwent 123 drug challenges. Only 1 patient was deemed to have a true positive drug challenge result. Twenty patients reported subjective symptoms during graded challenge, all of which were not deemed a positive challenge. There was a significantly higher proportion of patients who reported subjective symptoms in females, those with a higher number of listed drug allergies, and those whose historical reactions were primarily subjective in nature. Conclusion: Drug challenges are safe procedures in appropriately selected patients. A number of patients report subjective symptoms during drug challenges. Identifying patients at high risk for subjective symptoms may assist in determining whether placebo-controlled drug challenges should be performed.