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

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 Genotyping and Phenotyping of Platelets 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.