Up to 41% of fish-allergic patients may tolerate at least one bony fish based on the absence of PV-sIgE
To investigate possibly tolerated fish species based on the absence of PV-sIgE, we first determined the percentage of the patients negative to each investigated PV in each analyzed country (Figure 3A ). IgE of 78% of patients in total did not recognize ray PV, with the highest proportion of such patients in Luxembourg (97%) and the lowest in Spain (64%). 25% of patients were negative to sole PV (highest proportion in Luxembourg, 41%), while 19% in total and up to 38% (China) were negative to cod PV. To investigate how to best identify the absence of IgE to PV from specific species, the probability of an IgE test to be negative for a specific PV, when already negative for another specific PV, was calculated (Figure 3B ). Among the beta-PVs, tuna, mackerel and carp appeared as the best predictors of highly probable negative IgE tests for other beta PVs. For example, if negative for tuna PV, a probability of ≥90% exists for an IgE test to be negative for any other tested PV, except for salmon (71%). These findings should be considered when designing a panel of species for tolerance-confirming FC.