Figure Summary receiver operator characteristic curves (SROC) from all 22 papers including results on two assay types from six of the paper, so 28 results in total. Note we have only presented SROC curves as different stimulation index (SI) thresholds for a positive value were used across all studies. A - studies immediately analyzing whole blood with flow cytometry, n=17, I2=59.78% (95% CI 30.3 – 76.7%), tau20.292; B – studies measuring sulfidoleukotriene release, n=4, I2=26.9% (95% CI 0 – 72.5%), tau2 0.0; C – studies measuring histamine release , n=2, I2=15.8%, tau20; D studies using a direct method of observing basophils, n=2, I2=91.8% (95% CI71.7% - 97.6%), tau23.3713; D studies using an indirect method of observing basophils, n=2, I2=0%, tau20 .