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.