Discussion
Some studies suggest that the use of both sIgE and BAT together improves
sensitivity (41, 66). However, this opinion is not universally held, as
some groups have shown no improvement in sensitivity with the use of
sIgE and BAT together, and do not support the use of both methods (67).
The 2020 EAACI position paper suggests that “it is advisable to performin vitro tests in addition to ST in high-risk patients in order
to improve the sensitivity of the allergy workup and thus reduce the
need for DPT (moderate/strong)”, but does not clarifying if one or both
tests should be done, or which test is preferred (16). BAT shows clearly
improved sensitivity above sIgE (51% vs 19%), (13). However, including
BAT and sIgE with their respective specificity of 89% and 97%, would
still mean a small proportion of patients may erroneously be considered
positive for penicillin allergy after optimal assessment, despite being
able to tolerate penicillin. For BAT to become a routine part of the
diagnostic work up for penicillin, it must either have a sensitivity
that is high enough for it to be used as a screening test, or a
specificity higher than skin test or sIgE (>97%).
Alternatively, another potential use of BAT could be as in vitrodiagnostic option for identifying clavulanic acid-specific allergy.
Since hypersensitivity reactions to amoxicillin-clavulanic acid
co-association is very common, being able to determine if it is
clavulanic acid eliciting the allergic reaction would rescue amoxicillin
use as single drug formulation. To date there is no commercially
available sIgE to clavulanic acid. In two recent studies BAT was able
successfully diagnose clavulanic acid allergy in an adult population
(41, 68). This is another way that BAT can be used to accurately
determine true amoxicillin or clavulanic acid allergy.