Re-exposure to LOCM and recurrence of HSR
A recurrent HSR was defined as an immediate HSR on subsequent re-exposure to LOCM while undergoing CT, after a skin test had been performed. The LOCM administered at the time of the HSR was regarded as the culprit agent. Change of LOCM was defined as the use of an LOCM that had never been documented as a culprit agent in the affected individual. A premedication protocol, based on the severity of the HSR, was used according to institutional guidelines,3 the details of which were previously described.21 The incidence rate of recurrent immediate HSRs was calculated by dividing the number of cases that had an HSR within one hour after LOCM exposure by the number of all cases undergoing enhanced CT during the study period.