Clinical Characteristics of Glanzmann Thrombasthenia-First Results from the Glanzmann Thrombasthenia Natural History Study

Abstract

Introduction: Glanzmann Thrombasthenia (GT) is a severe inherited platelet disorder leading to an increased bleeding tendency. Bleeding phenotype is commonly assessed with the International Society on Thrombosis and Haemostasis (ISTH) Bleeding Assessment Tool (BAT). Method(s): The Glanzmann Thrombasthenia Natural History Study is an international multicenter observational cohort study initiated by the GT working group of the European Association for Haemophilia and Allied Disorders. This study was made possible in part by an unrestricted research grant of Hemab Aps. Data on clinical characteristics and patient reported outcomes on bleeding phenotype were collected. Besides the (self)-ISTH-BAT for lifetime bleeding, the self-administered Immune Thrombocytopaenia (ITP)-BAT assessed bleeding in the past month. Descriptive data are presented as means/medians and frequencies. Paired self-ITP-BAT differences (baseline vs. 6 months) were tested with Wilcoxon signed-rank and correlation with ISTH-BAT was assessed via Spearman's test. Result(s): Currently, 22 GT patients from 4 centers in the Netherlands and Italy have been included; 50% female, mean age 52 years (range 4-81). Median age at diagnosis was 2 years (IQR 0.5-14.0) and diagnosis was made based on genetic testing, biochemical diagnosis, or a combination of both in 9%, 41%, and 50% respectively. Mean ISTH-BAT score at inclusion was 15.7 (range 3-30). Based on the ISTH-BAT and self-ITP-BAT at inclusion, cutaneous bleeds (86%/81%), epistaxis (77%/76%), and bleeds from minor wound (73%/71%) were most commonly reported during lifetime and in the past month respectively. In the 13 patients who completed the self-ITP-BAT both at baseline (median 10, range 3-27) and 6 months (median 6, range 0-31), no significant difference between the scores was found (p = 0.107). There was a significant positive correlation between the self-ITPBAT and the ISTH-BAT scores at baseline (r=0.56, p=0.008). 41% of patients required medical treatment due to bleeding in the past month, and 82% of patients required platelet transfusion during lifetime. Discussion/Conclusion: The first results of the Glanzmann Thrombasthenia Natural History Study show that GT is a severe platelet disorder characterised by mucocutaneous bleeds, often requiring treatment. There seems to be a correlation between bleeding severity experienced over lifetime and that reported in the past month.