The ISTH bleeding assessment tool as predictor of bleeding events in inherited platelet disorders: Communication from the ISTH SSC Subcommittee on Platelet Physiology

The ISTH Bleeding Assessment Tool (ISTH‐BAT) has been validated for clinical screening of suspected von Willebrand disease (VWD) and for bleeding prediction. Recently it has been validated for subjects with inherited platelet disorders (IPD) (BAT‐VAL study). To determine whether the ISTH‐BAT bleeding score (BS) predicts subsequent bleeding events requiring treatment in IPD patients. Patients with IPD, type 1 VWD (VWD‐1) and age‐ and sex‐matched healthy controls enrolled in the BAT‐VAL study were prospectively followed‐up for 2 years and bleeding episodes requiring treatment were recorded. Of the 1098 subjects initially enrolled, 955 were followed‐up and 124 suffered hemorrhages during follow‐up, 60% of whom had inherited platelet function disorders (IPFD). Total number of events was significantly higher in IPFD (n= 235) than VWD‐1 (n= 52) or inherited thrombocytopenia (IT; n= 20). Events requiring transfusions were 66% in IPFD, 5.7% in VWD‐1, and 3% in IT. Baseline BS was significantly higher in IPFD patients with a bleeding event at follow‐up than in those without (p< .01) and the percentage of subjects suffering a bleeding event increased proportionally to baseline BS quartile. A significant association between the BS and the chance of suffering severe bleeding was found in the overall, IPFD, and VWD‐1 populations. Similar results were obtained for the pediatric population. Inherited platelet function disorder patients with high BS at enrollment are more likely to suffer from bleeding events requiring treatment at follow‐up. Moreover, the higher the baseline BS quartile the greater the incidence of subsequent events, suggesting that independently from diagnosis a high BS is associated with a greater risk of subsequent hemorrhage.