Background: The basophil activation test (BAT) has high accuracy to diagnose peanut allergy (PA) and can reduce the need for oral food challenges (OFC); however, so far it has not been incorporated in clinical practice. Methods: We compared two BAT methodologies, their performance in two separate laboratories, their diagnostic utility and impact of BAT in clinical-decision-making in a specialised centre. Results: 102 children being assessed for PA were tested on BAT (72 allergic, 30 sensitised tolerant). There was little internal variation (CV<15%) and a very strong correlation (Rs>0.95) between BAT performed across laboratories. The 2 BAT methods were correlated but not interchangeable and 19% of cases had opposite results. The in-house BAT method (IH-BAT) was superior, as demonstrated by its better diagnostic performance (area under the ROC curve 0.929/0.957 versus 0.892/0.895 for CD63/CD203c), lower number of non-responders (4% versus 14%), lower background basophil activation (4% versus 9%) and less need for oral food challenges (29/12 versus 37/20 for OFC/positive OFC). BAT was feasible and well-accepted by clinicians: no patient with positive BAT was referred for OFC; only 37% of all tested patients needed an OFC and 14% of these (5% of total) reacted during OFC, which corresponded to 72/89% decrease in OFC/positive OFC, respectively, with the integration of BAT in the diagnostic work-up for peanut allergy. Conclusions: The BAT is a robust test that can reliably be transferred between laboratories; however, different BAT methods are not interchangeable. BAT was well integrated in the clinical decision-making process in a specialised centre.

Newborn screening is an important public health measure of secondary prevention. With the increasing number of target conditions, there is a growing demand to optimize laboratory processes to save patient material and to work cost-effectively. Here, we report an adaption of the commercially available SpotOn Clinical Diagnostics tandem mass spectrometry test kit to detect hemoglobin fragments as well as substrate-product pairs of biotinidase and porphobilinogen synthase at once. The presence of specific peptides and the enzyme activities allows to infer to disease states, i.e., sickle cell disease, biotinidase deficiency and hereditary tyrosinemia type 1.