Introduction
With the recent advancement in the field of medical imaging equipment,
the use of iodinated low osmolar contrast media (LOCM) as a contrast
agent for computed tomography (CT) has substantially
increased.1 As a result, LOCM-related adverse
reactions, usually classified as toxic and rarely
immunologically-mediated hypersensitivity (HSR), have also
increased.2
The greatest risk factor for the development of recurrent HSR to
contrast media is a previous history of HSR.3,4 Two
main strategies have been widely used for managing patients with
previous immediate hypersensitivity according to severity:
premedication,3, 5-7 and change of the culprit
LOCM.8,9 The decision of which among these methods is
to be used is based on the severity of the HSR. For decades,
premedication has been the primary choice of care across the world for
preventing HSR .10-12 However, premedication cannot
completely prevent the recurrence of HSR, so called ‘breakthrough
reactions (BTRs)’, which occur in up to 17.1% of patients who
experienced a previous HSR to LOCM despite
premedication.3,13 A previous study reported that
changing the culprit LOCM to other one without skin test reduced the
recurrence of HSR from 31.1% to 7.6% in mild HSR
cases.9 However, there is no defined guideline for
choosing a safe alternative LOCM to prevent the recurrent HSR other than
avoiding the culprit agent. Therefore, it is of interest how to choose
the right and safe alternative LOCM which is non-reactive on systemic
re-exposure.
Skin testing to all patients who showed a prior HSR to LOCM is not
routinely recommended because of its relatively low sensitivity and an
unreliable positive predictive value.15 One option for
screening safe alternative(s) for re-exposure to contrast media is skin
testing with LOCM.14,15 However, its clinical
usefulness is not clearly validated yet and the choice of alternative
LOCMs is still unsolved problem since certain combinations of alternate
LOCM had no prophylactic effect.8 The cross-reactivity
by the
common
N-(2,3-dihydropoxypropyl)
carbamoyl
side chains found in LOCMs are believed to be a possible clue into
choosing safe alternatives for subsequent
re-exposure.18,19 There is, however, currently no
standard recommendation for deciding the optimal choice of safe
alternative LOCMs based on clinical evidence, such as outcomes of
re-exposure to contrast media.
The aim of this study was to evaluate the cross-reactivity between LOCMs
and the outcomes of LOCM re-administration based on the presence of
common carbamoyl side chain in patients who had immediate HSR.