Bleeding phenotype and diagnostic characterization of patients with congenital platelet defects

Phenotypic characterization of congenital platelet defects (CPDs) could help physicians recognize CPD subtypes and can inform on prognostic implications. We report the analyses of the bleeding phenotype and diagnostic characteristics of a large cohort of adult patients with a confirmed CPD. A total of 96 patients were analyzed and they were classified as Glanzmann thrombasthenia, Bernard-Soulier syndrome, dense granule deficiency, defects in the ADP or thromboxane A2 (TxA2) pathway, isolated thrombocytopenia or complex abnormalities. The median ISTH-BAT bleeding score was nine (IQR 5-13). Heavy menstrual bleeding (HMB) (80%), post-partum hemorrhage (74%), post-operative bleeds (64%) and post-dental extraction bleeds (57%) occurred most frequently. Rare bleeding symptoms were bleeds from the urinary tract (4%) and central nervous system (CNS) bleeds (2%). Domains with a large proportion of severe bleeds were CNS bleeding, HMB and post-dental extraction bleeding. Glanzmann thrombasthenia and female sex were associated with a more severe bleeding phenotype

Congenital platelet disorders and health status-related quality of life

Background: Patients with congenital blood platelet disorders (CPDs) demonstrate a predominantly mucocutaneous bleeding tendency. Repeated bleeds throughout life can have a significant impact on health status-related quality of life (HR-QoL), but few studies have investigated HR-QoL in patients with CPDs. Objectives: To determine HR-QoL in patients with suspected or confirmed CPDs as compared with the general Dutch population and to assess the association between bleeding phenotype and HR-QoL. Methods: Data were derived from the Thrombocytopathy in the Netherlands (TiN) study, a cross-sectional study of individuals suspected for a congenital platelet defect. TiN patients with an increased ISTH Bleeding Assessment Tool (ISTH-BAT) score (>3 in men and > 5 in women) were included for analysis. HR-QoL was assessed with the Short Form (SF)-36 survey. Bleeding symptoms were evaluated with the ISTH-BAT, resulting in a bleeding score. Results: One hundred fifty-six patients were analyzed, of whom 126 (81%) were women. Sixty-two patients (40%) had a confirmed CPD. Compared to the general Dutch population, patients with a suspected or confirmed CPD reported decreased physical functioning, limitations in daily activities due to physical health problems, limitations in social activities, decreased energy levels and fatigue, pain, and lower general health status. HR-QoL was not correlated with the ISTH-BAT score and was similar in patients with a confirmed CPD and those in whom a CPD could not be diagnosed. Conclusion: A bleeding tendency in patients with a suspected or confirmed CPD significantly impacts HR-QoL, independent of a confirmed explanatory diagnosis

The limitation of genetic testing in diagnosing patients suspected for congenital platelet defects

Thrombosis and Hemostasi

Flow cytometric mepacrine fluorescence can be used for the exclusion of platelet dense granule deficiency

Background: δ-storage pool disease (δ-SPD) is a bleeding disorder characterized by a reduced number of platelet-dense granules. The diagnosis of δ-SPD depends on the measurement of platelet ADP content, but this test is time consuming and requires a relatively large blood volume. Flow cytometric analysis of platelet mepacrine uptake is a potential alternative, but this approach lacks validation, which precludes its use in a diagnostic setting. Objectives: To evaluate the performance of platelet mepacrine uptake as a diagnostic test for δ-SPD. Patients/Methods: Mepacrine fluorescence was determined with flow cytometry before and after platelet activation in 156 patients with a suspected platelet function disorder and compared with platelet ADP content as a reference test. Performance was analyzed with a receiver operating characteristic (ROC) curve. Results: Eleven of 156 patients had δ-SPD based on platelet ADP content. Mepacrine fluorescence was inferior to platelet ADP content in identifying patients with δ-SPD, but both mepacrine uptake (area under the ROC curve [AUC] 0.87) and mepacrine release after platelet activation (AUC 0.80) had good discriminative ability. In our tertiary reference center, mepacrine uptake showed high negative predicitive value (97%) with low positive predictive value (35%). Combined with a negative likelihood ratio of 0.1, these data indicate that mepacrine uptake can be used to exclude δ-SPD in patients with a bleeding tendency. Conclusion: Mepacrine fluorescence can be used as a screening tool to exclude δ-SPD in a large number of patients with a suspected platelet function disorder

Flow cytometric mepacrine fluorescence can be used for the exclusion of platelet dense granule deficiency

Background: δ-storage pool disease (δ-SPD) is a bleeding disorder characterized by a reduced number of platelet-d

The limitation of genetic testing in diagnosing patients suspected for congenital platelet defects

Thrombosis and Hemostasi

Congenital platelet defects. Clinical features and diagnostic tests

Congenital platelet defects (CPDs) are rare disorders of primary hemostasis. Clinical characteristics and burden of disease are poorly described. Next to that, the current diagnostic tools lack sensitivity and specificity for CPDs. We are in need of improved platelet function diagnostics. This thesis aimed to gain insight into the bleeding phenotype and health-status related quality of life (HR-QoL) of patients with CPDs and to evaluate the diagnostic yield of advanced diagnostic tests. Chapter 2 reviewed the currently available diagnostic tests for platelet function and their pitfalls. The laboratory diagnostics entail many techniques and these are often insufficient to diagnose mild CPDs. We described flow cytometry and whole-exome sequencing (WES) as promising additional tests for diagnosing CPDs. In Chapter 3, we evaluated the bleeding phenotype and diagnostic characteristics of CPD patients. The most common diagnostic subgroups were ADP and thromboxane A2 pathway defects and isolated thrombocytopenia. The most common bleeding symptoms were heavy menstrual bleeding (HMB) and bleeds after a hemostatic challenge. Glanzmann thrombasthenia and female sex were associated with a more severe bleeding phenotype. In Chapter 4-6 we evaluated improved and advanced diagnostic tests. Chapter 4 showed that the self-administered ISTH bleeding assessment tool (self-BAT) was sufficiently reliable and feasible to detect a bleeding tendency in patients with (suspected) CPDs. This supports the use of the self-BAT as a screening tool. A self-BAT completed at home would save valuable time during an outpatient clinic visit and enhance screening before referral to the hemoaphilia treatment center for a suspected CPD. The diagnostic accuracy of mepacrine fluorescence measured on the flow cytometer for storage pool disease was evaluated in Chapter 5. This test showed good discriminative ability and, although the sensitivity and specificity were moderate, we showed that this test can be used to exclude storage pool disease in patients suspected for a CPD. A DNA-based approach has been proposed to increase the diagnostic rate of CPDs. Genetic analysis can provide accurate diagnoses and is proposed to be performed as a first-line investigation. However, Chapter 6 showed a limited diagnostic yield of genetic testing with a selected gene panel in patients suspected for a CPD. We recommended to not perform genetic analysis as a first-line investigation, but only in patients in whom a CPD is confirmed. Chapter 7 reported the HR-QoL of patients with suspected or confirmed CPDs. We showed that HR-QoL is significantly impaired in suspected or confirmed CPD patients as compared to the general Dutch population and that this patient group is one to care for. Taken together, this thesis contributed to our understanding of CPDs. We gained insight into the clinical characteristics and burden of disease of patients with CPDs and showed the advantages and limitations of advanced diagnostic tests. In the near future, we should continue to put these patients in the spotlight in order to create awareness among health professionals and society and we should continue to gain insight into platelet pathophysiology and molecular mechanisms in order to improve the diagnostic work-up for CPDs

Congenital platelet defects. Clinical features and diagnostic tests

Congenital platelet defects (CPDs) are rare disorders of primary hemostasis. Clinical characteristics and burden of disease are poorly described. Next to that, the current diagnostic tools lack sensitivity and specificity for CPDs. We are in need of improved platelet function diagnostics. This thesis aimed to gain insight into the bleeding phenotype and health-status related quality of life (HR-QoL) of patients with CPDs and to evaluate the diagnostic yield of advanced diagnostic tests. Chapter 2 reviewed the currently available diagnostic tests for platelet function and their pitfalls. The laboratory diagnostics entail many techniques and these are often insufficient to diagnose mild CPDs. We described flow cytometry and whole-exome sequencing (WES) as promising additional tests for diagnosing CPDs. In Chapter 3, we evaluated the bleeding phenotype and diagnostic characteristics of CPD patients. The most common diagnostic subgroups were ADP and thromboxane A2 pathway defects and isolated thrombocytopenia. The most common bleeding symptoms were heavy menstrual bleeding (HMB) and bleeds after a hemostatic challenge. Glanzmann thrombasthenia and female sex were associated with a more severe bleeding phenotype. In Chapter 4-6 we evaluated improved and advanced diagnostic tests. Chapter 4 showed that the self-administered ISTH bleeding assessment tool (self-BAT) was sufficiently reliable and feasible to detect a bleeding tendency in patients with (suspected) CPDs. This supports the use of the self-BAT as a screening tool. A self-BAT completed at home would save valuable time during an outpatient clinic visit and enhance screening before referral to the hemoaphilia treatment center for a suspected CPD. The diagnostic accuracy of mepacrine fluorescence measured on the flow cytometer for storage pool disease was evaluated in Chapter 5. This test showed good discriminative ability and, although the sensitivity and specificity were moderate, we showed that this test can be used to exclude storage pool disease in patients suspected for a CPD. A DNA-based approach has been proposed to increase the diagnostic rate of CPDs. Genetic analysis can provide accurate diagnoses and is proposed to be performed as a first-line investigation. However, Chapter 6 showed a limited diagnostic yield of genetic testing with a selected gene panel in patients suspected for a CPD. We recommended to not perform genetic analysis as a first-line investigation, but only in patients in whom a CPD is confirmed. Chapter 7 reported the HR-QoL of patients with suspected or confirmed CPDs. We showed that HR-QoL is significantly impaired in suspected or confirmed CPD patients as compared to the general Dutch population and that this patient group is one to care for. Taken together, this thesis contributed to our understanding of CPDs. We gained insight into the clinical characteristics and burden of disease of patients with CPDs and showed the advantages and limitations of advanced diagnostic tests. In the near future, we should continue to put these patients in the spotlight in order to create awareness among health professionals and society and we should continue to gain insight into platelet pathophysiology and molecular mechanisms in order to improve the diagnostic work-up for CPDs

Reliability and Feasibility of the Self-Administered ISTH-Bleeding Assessment Tool

Introduction  Standardized bleeding assessment tools (BATs), such as the International Society for Thrombosis and Hemostasis (ISTH)-BAT, are screening instruments used during the diagnostic workup of suspected bleeding disorders. A self-administered ISTH-BAT (self-BAT) would enhance screening and save time during an outpatient clinic visit. Aim  This study was aimed to investigate the reliability and feasibility of the self-BAT. Methods  The electronic self-BAT was created from the ISTH-BAT and paper-version of self-BAT and optimized by patients and physicians. Patients with a (suspected) congenital platelet defect (CPD), who had previously undergone physician-administered ISTH-BAT assessment, were invited to complete the self-BAT. Optimal self-BAT cut-off values to detect a bleeding tendency, as defined by the ISTH-BAT, were evaluated by receiver operator characteristic (ROC) curve analysis to reach a sensitivity ≥95%. Reliability was tested by assessing sensitivity, specificity, and intraclass correlation (ICC). Feasibility was evaluated on comprehension and length of self-BAT. Results  Both versions of the BAT were completed by 156 patients. Optimal cut-off values for self-BAT to define a bleeding tendency were found to be identical to those of the ISTH-BAT. Normal/abnormal scores of the ISTH-BAT and self-BAT were agreed in 88.5% (138/156, 95% confidence interval [CI]: 0.83-0.93) of patients. The sensitivity and specificity of the self-BAT to detect a bleeding tendency were 96.9 and 48.1%, respectively. The ICC was 0.73. Self-BAT questions were graded by 96.8% (151/156) as "very easy," "easy," and "satisfactory" and questionnaire length as "exactly right" by 91% (142/156) of patients. Conclusion  In patients with a (suspected) CPD, the self-BAT is sufficiently reliable and feasible to detect a bleeding tendency, which supports its use as a screening tool