Utility of the ISTH bleeding assessment tool in predicting platelet defects in participants with suspected inherited platelet function disorders

Summary Background The ISTH bleeding assessment tool ( ISTH ‐ BAT ) was developed to record bleeding symptoms and to aid diagnosis in patients with a possible bleeding disorder. Objectives To investigate the utility of the ISTH ‐ BAT in predicting functional defects in platelet activation in participants with suspected inherited platelet function disorders. Patients/Methods Participants with clinical evidence of excessive bleeding and suspected inherited platelet function disorders and healthy volunteers were recruited to the G enotyping and P henotyping of P latelets study ( GAPP ; ISRCTN  77951167). The ISTH ‐ BAT questionnaire was applied by a trained investigator prior to lumiaggregometry. Results One hundred participants were included (79 with suspected inherited platelet function disorders, and 21 healthy volunteers). The ISTH ‐ BAT score in participants with suspected inherited platelet function disorders (median 12; interquartile range [ IQR ] 8–16) was significantly higher than in healthy volunteers (median 0; IQR  0–0). There was no difference between participants with suspected inherited platelet function disorders with a platelet defect detected by lumiaggregometry (median 11; IQR  8–16) and those with normal platelet function (median 12; IQR  8–14) ( P  > 0.05). The ISTH ‐ BAT score was not associated with a demonstrable platelet defect on platelet function testing (area under the receiver operating characteristic curve = 0.501 [95% confidence interval 0.372–0.630, P  = 0.98] and odds ratio 1.01 [95% confidence interval 0.93–1.09, P  = 0.91]). Conclusions The ISTH ‐ BAT is a powerful tool for documenting lifelong bleeding history. However, the score obtained is not predictive of the presence of a platelet defect on lumiaggregometry in patients with suspected inherited platelet function disorders.