Bleeding scores: are they really useful?

Diagnostic pitfalls and conundrums in type 1 von Willebrand disease

Most people with von Willebrand disease (VWD) have a partial quantitative deficiency of plasma von Willebrand factor (VWF) or type 1 VWD. In contrast to type 2 and type 3 VWD, laboratory assays will not always establish the diagnosis in type 1 VWD. This is because plasma VWF levels in type 1 VWD, especially those with levels closer to 50 IU/dL, overlap with the general population. Assessment is further complicated by increased plasma VWF levels in response to physiologic stressors or aging. Diagnosis of those with type 1 VWD with plasma VWF levels 30 to 50 IU/dL (previously referred to as "low VWF") requires expert assessment of bleeding phenotype as well as an understanding of the limitations of both bleeding assessment tools (BATs) and laboratory testing. Using the available evidence and highlighting research gaps, we discuss common dilemmas facing providers relating to assessment of adolescents, transition from pediatrics to adult care, and older individuals with type 1 VWD.

Reducing use of coagulation tests in a family medicine practice setting: An implementation study

Introduction

Clinicians often order the international normalized ratio (INR) and activated partial thromboplastin time (APTT) to evaluate for the possibility of inherited bleeding disorders despite sensitivities and specificities of 1%-2%. The most accurate tool to evaluate for bleeding disorders is a validated bleeding assessment tool (BAT). Our aim was to reduce coagulation testing by >50% in a large family practice in Ontario, Canada.

Methods

We conducted an implementation study from May 2016 to February 2020. Iterative interventions included introduction of a validated BAT into the electronic medical record (EMR); removal of the APTT as a prepopulated selection from the laboratory requisition; and education targeting family medicine teams and laboratory personnel. The primary outcome was the rate of pre- and post-APTT testing. Creatinine testing was the control. Data were analyzed via an interrupted time series analysis using Stata 13.

Results

Immediately following education of the laboratory personnel on coagulation testing, the APTT rate level dropped by 1.26 tests per 100 patient visits per month (p < 0.001) and was sustained until the end of the study. Meanwhile, the PT/INR and creatinine testing rate levels did not change (rate level = -0.02 per 100 visits per month, p = 0.79 and 0.49, p = 0.22 respectively). There was good uptake of the BAT following integration and 18/88 (20%) obtained a referral to hematology after BAT completion.

Conclusions

Multidisciplinary, iterative interventions reduced APTT testing and enabled the use of BATs to guide hematology referrals in a large family practice.

Treatment Algorithm for Patients With von Willebrand Syndrome Type 2A and Congenital Heart Disease-A Treatment Algorithm May Reduce Perioperative Blood Loss in Children With Congenital Heart Disease

OBJECTIVES

In children with congenital heart disease (CHD), excessive perioperative bleeding is associated with increased morbidity and mortality, thus making adequate perioperative hemostasis crucial. We investigate the prevalence of acquired von Willebrand syndrome type 2A (aVWS) in CHD and develop a treatment algorithm for patients with aVWS and CHD (TAPAC) to reduce perioperative blood loss.

DESIGN

Retrospective cohort study.

SETTING

Single-center study.

PATIENTS

A total of 627 patients with CHD, undergoing corrective cardiac surgery between January 2008 and May 2017.

INTERVENTIONS

The evaluation of perioperative bleeding risk was based on the laboratory parameters von Willebrand factor (VWF) antigen, ristocetin cofactor activity, platelet function analyzer (PFA) closure time adenosine diphosphate, and PFA epinephrine. According to the bleeding risk, treatment was performed with desmopressin or VWF.

MEASUREMENTS AND MAIN RESULTS

aVWS was confirmed in 63.3 %, with a prevalence of 45.5% in the moderate and 66.3 % in the high-risk group. In addition, prevalence increased with ascending peak velocity above the stenosis (v max ) from 40.0% at less than or equal to 3 m/s to 83.3% at greater than 5 m/s. TAPAC reduced mean blood loss by 36.3% in comparison with a historical control cohort ( p &lt; 0.001), without increasing the number of thrombotic or thromboembolic events during the hospital stay. With ascending v max , there was an increase in perioperative blood loss in the historical cohort ( p &lt; 0.001), which was not evident in the TAPAC cohort ( p = 0.230).

CONCLUSIONS

The prevalence of aVWS in CHD seems to be higher than assumed and leads to significantly higher perioperative blood loss, especially at high v max . Identifying these patients through appropriate laboratory analytics and adequate treatment could reduce blood loss effectively.

The Society for Obstetric Anesthesia and Perinatology Interdisciplinary Consensus Statement on Neuraxial Procedures in Obstetric Patients With Thrombocytopenia

Because up to 12% of obstetric patients meet criteria for the diagnosis of thrombocytopenia in pregnancy, it is not infrequent that the anesthesiologist must decide whether to proceed with a neuraxial procedure in an affected patient. Given the potential morbidity associated with general anesthesia for cesarean delivery, thoughtful consideration of which patients with thrombocytopenia are likely to have an increased risk of spinal epidural hematoma with neuraxial procedures, and when these risks outweigh the relative benefits is important to consider and to inform shared decision making with patients. Because there are substantial risks associated with withholding a neuraxial analgesic/anesthetic procedure in obstetric patients, every effort should be made to perform a bleeding history assessment and determine the thrombocytopenia etiology before admission for delivery. Whereas multiple other professional societies (obstetric, interventional pain, and hematologic) have published guidelines addressing platelet thresholds for safe neuraxial procedures, the US anesthesia professional societies have been silent on this topic. Despite a paucity of high-quality data, there are now meta-analyses that provide better estimations of risks. An interdisciplinary taskforce was convened to unite the relevant professional societies, synthesize the data, and provide a practical decision algorithm to help inform risk-benefit discussions and shared decision making with patients. Through a systematic review and modified Delphi process, the taskforce concluded that the best available evidence indicates the risk of spinal epidural hematoma associated with a platelet count ≥70,000 × 106/L is likely to be very low in obstetric patients with thrombocytopenia secondary to gestational thrombocytopenia, immune thrombocytopenia (ITP), and hypertensive disorders of pregnancy in the absence of other risk factors. Ultimately, the decision of whether to proceed with a neuraxial procedure in an obstetric patient with thrombocytopenia occurs within a clinical context. Potentially relevant factors include, but are not limited to, patient comorbidities, obstetric risk factors, airway examination, available airway equipment, risk of general anesthesia, and patient preference.

Use of electronic self-administered bleeding assessment tool in diagnosis of paediatric bleeding disorders

INTRODUCTION

In the era of electronic medical records, pen-and-paper-based physician-administered bleeding assessment tools (BAT) remain under-utilized in the clinical setting, as they are noted to be time-consuming.

AIM

The current study reviews the use of an electronic self-administered bleeding assessment tool (eBAT) prospectively in a paediatric haematology clinic and in comparison with a physician administered BAT (pBAT).

MATERIALS AND METHODS

This was reviewed and approved in the current form because the aims statement includes the method regarding comparison of 2 groups. So no additional section required.

RESULTS

A total of 94 BAT response pairs were available for analysis. The median time required for patients or parents to complete the eBAT was 8 min, with less than a third of the patients requiring over 10 min. The median bleeding scores noted in this study were 4 for both the BATs, with strong positive correlation between the eBAT and the physician administered bleeding questionnaire. The eBAT had a sensitivity of 93.8% (95% CI 82.8%-98.7%), a specificity of 34.8% (95% CI 21.4%-50.3%), a positive predictive value (PV) of 60.0% (95% CI 54.5%-65.2%) and a negative PV of 84.2% (95% CI 62.5%-94.5%) for identifying a bleeding disorder.

CONCLUSIONS

Findings indicate that eBAT is a valid and time-efficient screening tool for evaluating patients' bleeding symptoms, which can improve clinical applicability of BATs by reducing time for bleeding history review.

Hemostasis Laboratory Diagnostics: Characteristics, Communication Issues, and Current Challenges Resulting from Centralization of Laboratory Medicine

Laboratory diagnostics of patients with bleeding and thrombotic disorders can be a delicate task, which requires special skills and expertise. In this article, characteristic features of hemostasis testing are reviewed, including staged protocols and synoptic assessment of the patient history, clinical symptoms, and laboratory findings. Despite major progress in the diagnostic and therapeutic management, centralized testing of hemostasis can be associated with substantial challenges, resulting from the current dissociation between the clinical and laboratory world. To address some of these challenges, possible solutions are discussed, including adaptation of an established working paradigm.

Bleeding assessment tools to predict von Willebrand disease: Utility of individual bleeding symptoms

BACKGROUND

Bleeding assessment is part of the diagnostic workup of von Willebrand disease (VWD). Bleeding assessment tools (BATs) have standardized obtaining this information but have been criticized because they are time consuming.

OBJECTIVE

To use our legacy data to determine which questions from BATs are the strongest predictors of a VWD diagnosis.

PATIENTS/METHODS

Bleeding score data from 3 different BATs were used. Patients aged <12 years were excluded. Questions on BATs relate to different bleeding symptoms, and each symptom is scored by severity. Scores for each symptom were sorted based on whether they indicated clinically significant bleeding, and nonsignificant scores were set as the reference category. Multivariable logistic regression was used to determine the symptoms that were the strongest predictors of a laboratory-confirmed VWD diagnosis.

RESULTS

A total of 927 participants were included; 144 (16%) were patients with VWD, and 783 (84%) were healthy controls. The top 3 symptoms for which a clinically significant positive response increased the likelihood of VWD were hemarthrosis (odds ratio [OR], 19.2; 95% confidence interval [CI], 3.7-100.4), postsurgical bleeding (OR, 15.2; 95% CI, 5.9-38.9), and menorrhagia (OR, 10.3; 95% CI, 4.9-21.9). With each increase in number of bleeding symptom categories with clinically significant scores, subjects had a stepwise increase in odds of a VWD diagnosis.

CONCLUSIONS

Our results suggest that most of the bleeding symptoms on BATs are significant predictors of VWD, and there is value in assessing multiple bleeding symptoms when eliciting a bleeding history. Certain bleeding symptoms are more useful predictors than others. Future BAT revisions may consider adding a relative weighting to each symptom.

Utility of repeat testing in the evaluation for von Willebrand disease in pediatric patients

BACKGROUND

Von Willebrand disease (VWD) is the most common inherited bleeding disorder and is caused by quantitative and qualitative defects in von Willebrand factor (VWF). The laboratory diagnosis of VWD in pediatric patients is complicated by VWF interassay and intra-assay variability, stress-induced elevations in VWF levels, and a lack of significant bleeding history with which to correlate test results.

OBJECTIVE

Guidelines recommend repeat testing in patients with a high suspicion of VWD and unclear laboratory assay results; however, no studies have evaluated the utility of repeat VWF testing in pediatric patients.

METHODS

This retrospective single-center cohort study aimed to determine clinical variables associated with requiring more than one test to diagnose VWD and to establish a cutoff VWF value above which further testing is not informative.

RESULTS

Of 811 patients evaluated for a suspected bleeding disorder, 22.2% were diagnosed with VWD, with ~70% diagnosed on the first test. Patients with VWD were younger (5.8 vs. 8.5 years, P = .002) and more likely to have a family history of VWD (38% vs. 22%, P < .001) than those without VWD. Univariate analysis failed to identify any clinical variables that correlated with needing multiple tests for a VWD diagnosis. A cutoff of 100 IU/dL for VWF antigen or activity on the first test yielded negative predictive values >95%.

CONCLUSIONS

We demonstrate that the majority of pediatric patients had diagnostic VWF values on the first set of testing. Pediatric patients without a family history of VWD and VWF levels >100 IU/dL may not need further testing to rule out the diagnosis of VWD.

Fundamentals for a Systematic Approach to Mild and Moderate Inherited Bleeding Disorders: An EHA Consensus Report

Healthy subjects frequently report minor bleedings that are frequently ‘background noise’ of normality rather than a true disorder. Nevertheless, unexpected or unusual bleeding may be alarming. Thus, the distinction between normal and pathologic bleeding is critical. Understanding the underlying pathologic mechanism in patients with an excessive bleeding is essential for their counseling and treatment. Most of these patients with significant bleeding will result affected by non-severe inherited bleeding disorders (BD), collectively denominated mild or moderate BD for their relatively benign course. Unfortunately, practical recommendations for the management of these disorders are still lacking due to the current state of fragmented knowledge of pathophysiology and lack of a systematic diagnostic approach. To address this gap, an International Working Group (IWG) was established by the European Hematology Association (EHA) to develop consensus-based guidelines on these disorders. The IWG agreed that grouping these disorders by their clinical phenotype under the single category of mild-to-moderate bleeding disorders (MBD) reflects current clinical practice and will facilitate a systematic diagnostic approach. Based on standardized and harmonized definitions a conceptual unified framework is proposed to distinguish normal subjects from affected patients. The IWG proposes a provisional comprehensive patient-centered initial diagnostic approach that will result in classification of MBD into distinct clinical-pathological entities under the overarching principle of clinical utility for the individual patient. While we will present here a general overview of the global management of patients with MBD, this conceptual framework will be adopted and validated in the evidence-based, disease-specific guidelines under development by the IWG.

Predictive value of a bleeding score for postpartum hemorrhage

BACKGROUND

A reliable screening tool that could contribute to the identification of women with an increased risk of postpartum hemorrhage would be of great clinical significance.

OBJECTIVES

The aim of this study was to examine the added predictive value of a bleeding assessment tool for postpartum hemorrhage exceeding 1000 mL.

PATIENTS/METHODS

Prospective two-center cohort study among 1147 pregnant women visiting the outpatient clinic or the maternity ward who completed a bleeding assessment tool prior to birth. The condensed MCMDM-1VWD bleeding assessment tool was adjusted to a questionnaire that could be used as a self-assessment bleeding tool. A score of ≥4 was considered to be abnormal.

RESULTS

In the 1147 pregnant women in our cohort, bleeding scores ranged from -3 to 13, with a median of 1 (IQR -1 to 3); 197 (17%) women developed postpartum hemorrhage. Among women with a history of postpartum hemorrhage 29% developed postpartum hemorrhage. Among 147 women with an abnormal bleeding score (≥4), 27 (18%) developed postpartum hemorrhage, whereas the remaining 170 cases of postpartum hemorrhage had a normal bleeding score. Despite the high incidence of postpartum hemorrhage, the ability of the bleeding score to predict postpartum hemorrhage was poor: area under receiver operating curve 0.53 (95% CI 0.49-0.58) for postpartum hemorrhage (PPH) ≥1000 mL.

CONCLUSIONS

A history of significant postpartum hemorrhage was associated with an increased risk of subsequent postpartum hemorrhage. However, screening with a bleeding assessment tool did not help to discriminate women who will develop postpartum hemorrhage from women who will not.

Prevalence of Macrothrombocytopenia in Healthy College Students in Western India

Macrothrombocytopenia is being increasingly described across the globe. There is paucity of data on the prevalence of this condition from different parts of India. 10,047 healthy college students from the city of Surat in western India were investigated for macrothrombocytopenia i.e. those with Mean platelet Volume of > 11 fL and platelet count of less than 150 × 10⁹/L. ABO blood groups, complete blood counts, peripheral smear examination and haemoglobinopathy work up was also done. Siblings and parents of the macrothrombocytopenic individuals were also studied when available. Bleeding assessment tool of International society of thrombosis and haemostasis were applied to see if there were excessive bleeding in macrothrombocytropenia patients. One hundred and ninety-six students (1.95%) had asymptomatic macrothrombocytopenia. More female students (P < 0.0001) had this condition and blood group A was under represented (P = 0.019) with this condition. Prevalence of macrothrombocytopenia was not related to ethnic subgroups to which the students belonged to, nor was it linked to presence of any haemoglobinopathy gene. In 38 of the 52, 1st degree relatives studied macrothrombocytopenia was confirmed at least in one of them. Excessive bleeding in none of the individuals with macrothrombocytopenia was noted. Asymptomatic macrothrombocytopenia is rare in western parts of India and affects 1.95% of the healthy population. Females were over represented with this condition raising a suspicion of X linked dominant inheritance. Underrepresentation of blood group A in this condition requires further study.

Diagnostic challenges of inherited mild bleeding disorders: a bait for poorly explored clinical and basic research

The best-known inherited mild bleeding disorders (MBDs), i.e. type 1 von Willebrand disease (VWD), platelet function disorders (PFDs), and mild to moderate clotting factor deficiencies, are characterized clinically by mucocutaneous bleeding, and, although they are highly prevalent, still pose difficult diagnostic problems. These include establishing the pathological nature of bleeding, and the uncertainties surrounding the clinical relevance of laboratory results. Furthermore, the high frequency of bleeding symptoms in the normal population and the subjective appraisal of symptoms by patients or parents makes elucidating the pathological nature of bleeding difficult. Standardized bleeding assessment tools and semiquantitative bleeding scores (BSs) help to discriminate normal from abnormal bleeding. However, as most MBDs have similar bleeding patterns, for example, bleeding sites, frequency, and severity, BSs are of little help for diagnosing specific diseases. Global tests of primary hemostasis (bleeding time; PFA-100/200) lack sensitivity and, like BSs, are not disease-specific. Problems with the diagnosis of type 1 VWD and PFD include assay standardization, uncertain definition of von Willebrand factor cut-off levels, and the lack of universal diagnostic criteria for PFD. Regarding clotting factor deficiencies, the bleeding thresholds of some coagulation factors, such as factor VII and FXI, are highly variable, and may lead to misinterpretation of the clinical relevance of mild to moderate deficiencies. Remarkably, a large proportion of MBDs remain undiagnosed even after comprehensive and repeated laboratory testing. These are tentatively considered to represent bleeding of undefined cause, with clinical features indistinguishable from those of classical MBD; the pathogenesis of this is probably multifactorial, and unveiling these mechanisms should constitute a fertile source of translational research.

von Willebrand Disease: Diagnostic Strategies and Treatment Options

von Willebrand disease (VWD) is one of the most common inherited bleeding disorders. Since its first description in 1926, the diagnosis and management of VWD has significantly improved due to increasing scientific knowledge of the genetics and biology of von Willebrand factor (VWF). This article reviews the molecular structure and function of VWF as well as the clinical symptoms, laboratory-based diagnostic workup, and classification schema for VWD. It highlights current treatment options and state-of-the art research in VWF and VWD.

Bleeding score in type 1 von Willebrand disease patients using the condensed MCMDM-1 vWD validated questionnaire

BACKGROUND

Assessment of the severity of bleeding symptom has led to the evolution of bleeding assessment tools which are now validated.

AIMS

To administer the condensed molecular and clinical markers for the diagnosis and management of type 1 von Willebrand disease VWD (MCMDM-1 vWD) questionnaire to the Omani type 1 vWD patients and correlate it with the laboratory parameters.

METHODS

Patients and controls were personally interviewed and the condensed MCMDM-1 vWD questionnaire administered by a single investigator. Bleeding score (BS) was calculated, based on the presence or absence of the bleeding symptoms according to a standard validated questionnaire in both the patients and the controls.

RESULTS

The median age of the patient cohort was 27 (range, 7-49) years with 60.87% of females. The median time to administer condensed MCMDM-1 BS questionnaire was 11 minutes (interquartile range-IQR;7,16). Overall, bleeding from the oral cavity was the most predominant symptom (63%). The median BS was 5 (IQR;1,8) although individual scores ranged between 0 and 29. However, there was no statistically significant difference in BS between genders (males: median 4; IQR 1,6 and females: median 5, IQR 1,10) (P > .05, Kruskal-Wallis test) The Spearman's correlation value of BS was weak with FVIII:C levels and von Willebrand Ristocetin co-factor activity; very weak with von Willebrand Antigen level, and moderate with vonWillebrand Collagen Binding activity being -0.29, -0.28, -0.14 and -0.43, respectively.

CONCLUSION

The BS reflects the severity of bleeding among the vWD patients. Although the BS was abnormal, it did not correlate significantly with the surrogate laboratory parameters [P > .05].

Bleeding score in Type 1 von Willebrand disease patients using the ISTH-BAT questionnaire

BACKGROUND

Bleeding assessment tools have evolved in the last decade to standardize the assessment of the severity of bleeding symptom in a consistent way. In 2010, the International Society on Thrombosis and Hemostasis-Bleeding Assessment Tool (ISTH-BAT) was developed and validated.

AIMS

Our aim was to administer ISTH-BAT questionnaire to the Omani patients with type 1 VWD and obtain the bleeding score (BS). We also studied the severity of their bleeding symptoms and correlated it with the BS as well as with the laboratory parameters.

METHODS

Forty-eight type I VWD index cases and 52 normal subjects were interviewed and the ISTH-BAT questionnaire administered. The BS was calculated based on a history of bleeding symptoms from 12 different sites according to the standard ISTH-BAT questionnaire. Laboratory parameters were obtained from patient's medical records.

RESULTS

The mean age of this cohort was 27 years (range, 6-49) with 60% being females. The median time to administer this questionnaire was 10 minutes with an interquartile range (IQR) from 8 to 17 minutes. Overall, the median BS was 7 (IQR; 2,11) although individual scores ranged between 0 and 36. The BS was negatively correlated with VWF: Ag, VWF: RCo, and VWF: CB and the Spearman's correlation coefficient "rho" was, respectively, -0.15, -0.08, and -0.22.

CONCLUSION

The ISTH-BAT BS is designed to reflect the severity of bleeding. Our results demonstrate the inherent variability of this bleeding pattern. We also found that the ISTH-BAT BS significantly correlated with VWF: Ag and VWF: CB.

Unclassified bleeding disorders: outcome of haemostatic challenges following tranexamic acid and/or desmopressin

INTRODUCTION

In a minority of patients with a significant bleeding history no cause is found despite extensive testing and we diagnose such cases as unclassified bleeding disorders (UBD). UBDs may have diverse underlying causes and currently no standard management strategy exists in the event of a haemorrhage or to cover surgery.

AIM

To document the clinical characteristics and response to treatment of UBDs.

METHODS

We performed a retrospective chart review of all patients with UBDs who had an invasive procedure at our centre between 1998 and 2014.

RESULTS

The commonest symptoms were menorrhagia (89%) and bleeding at the time of surgery (88%) or dental extraction (85%). A total of 33 patients underwent 78 minor and major haemostatic challenges. Haemostatic cover was provided in 28 procedures with tranexamic acid alone, two with desmopressin and 45 with both agents in combination. A successful haemostatic outcome was observed in 70/78 (90%) cases. No patient required additional surgical intervention to achieve haemostasis, but one patient required a platelet transfusion to control postoperative bleeding.

CONCLUSIONS

This is the first study to report on the investigation and treatment of UBD. Future studies are needed to further our understanding of the bleeding phenotype and identify any underlying causes.

How I treat type 2 variant forms of von Willebrand disease

Type 2 von Willebrand disease (VWD) includes a wide range of qualitative abnormalities of von Willebrand factor structure and function resulting in a variable bleeding tendency. According to the current classification, 4 different subtypes can be identified, each with distinctive phenotypic and therapeutic characteristics. Current available laboratory methods allow a straightforward approach to VWD subtyping, and although the precise molecular characterization remains complex, it is not required for appropriate treatment of the vast majority of cases. Desmopressin can be useful only in a few type 2 cases compared with patients with actual quantitative deficiency (type 1), most often in variants with a nearly normal multimeric pattern (type 2M). However, since no laboratory test accurately predicts response to desmopressin, a trial test should always be performed in all type 2 VWD patients, with the exception of type 2B ones. Replacement therapy with plasma-derived von Willebrand factor-factor VIII concentrates represents the safe mainstay of treatment of all patients, particularly those not responding to desmopressin or requiring a sustained hemostatic correction because of major surgery or bleeding. A significant patient bleeding history correlates with increased bleeding risk and should be considered in tailoring the optimal antihemorrhagic prophylaxis in the individual patient.

Systematic Analysis of Bleeding Phenotype in PT-VWD Compared to Type 2B VWD Using an Electronic Bleeding Questionnaire

Objective:

To investigate the utility of an electronic version of the condensed molecular and clinical markers for the diagnosis and management of type 1 von Willebrand disease (VWD) bleeding questionnaire (eBQ) in assessing the bleeding phenotype in platelet-type VWD (PT-VWD) and compare it to its closely similar disorder, type 2B VWD.

Methods:

Retrospective analysis of the clinical bleeding and laboratory phenotype of 13 patients with PT-VWD and 12 type 2B VWD.

Results:

Bleeding score (BS) was significantly lower in PT-VWD as compared to type 2B. Bleeding score correlated with platelet count and von Willebrand factor:Ristocetin cofactor activity in PT-VWD but not in type 2B with a significant reduction in platelet count in type 2B VWD compared to PT-VWD. The eBQ had sensitivity of 62% in PT-VWD and 92% in type 2B VWD.

Conclusion:

Objective analysis of bleeding symptoms further the understanding of the phenotype of 2 closely similar bleeding disorders for better diagnosis and follow-up. Larger international prospective studies are warranted to evaluate the utility of the eBQ in PT-VWD and other rare bleeding disorders.

Bleeders, bleeding rates, and bleeding score

Bleeding symptoms are frequently reported even in otherwise healthy subjects, and differentiating a normal subject from a patient with a mild bleeding disorder (MBD) can be extremely challenging. The concept of bleeding rate, that is, the number of bleeding episodes occurring within a definite time, could be used as the unifying framework reconciling the bleeding risk observed in congenital and acquired coagulopathies into a single picture. For instance, primary prevention trials have shown that the incidence of non-major bleeding symptoms in normal subjects is around five per 100 person-years, and this figure is in accordance with the number of hemorrhagic symptoms reported by normal controls in observational studies on hemorrhagic disorders. The incidence of non-major bleeding in patients with MBDs (e.g. in patients with type 1 VWD carrying the C1130F mutation) is also strikingly similar with that of patients taking antiplatelet drugs, and the incidence in moderately severe bleeding disorders (e.g. type 2 VWD) parallels that of patients taking vitamin K antagonists. The severity of a bleeding disorder may therefore be explained by a bleeding rate model, which also explains several common clinical observations. Appreciation of the bleeding rate of congenital and acquired conditions and of its environmental/genetic modifiers into a single framework will possibly allow the development of better prediction tools in the coming years and represents a major scientific effort to be pursued.

Prevalence of disease and relationships between laboratory phenotype and bleeding severity in platelet primary secretion defects

BACKGROUND

The prevalence of platelet primary secretion defects (PSD) among patients with bleeding diathesis is unknown. Moreover, there is paucity of data on the determinants of bleeding severity in PSD patients.

OBJECTIVE

To determine the prevalence of PSD in patients with clinical bleeding and to study the relationships between the type of platelet defect and bleeding severity.

METHODS

Data on patients referred for bleeding to the Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan (Italy) in the years between 2008 and 2012 were retrieved to study the prevalence of PSD. Demographic, clinical and laboratory information on 32 patients with a diagnosis of PSD was used to compare patients with or without associated medical conditions and to investigate whether or not the type and extension of platelet defects were associated with the bleeding severity score (crude and age-normalized) or with the age at first bleeding requiring medical attention.

RESULTS

The estimated prevalence of PSD among 207 patients with bleeding diathesis and bleeding severity score above 4 was 18.8% (95% confidence interval [CI]: 14.1-24.7%). Patients without associated medical conditions had earlier age of first bleeding (18 vs 45 years; difference: -27 years; 95% CI: -46 to -9 years) and different platelet functional defect patterns (Fisher's exact test of the distribution of patterns, P = 0.007) than patients with accompanying medical conditions. The type and extension of platelet defect was not associated with the severity of bleeding.

CONCLUSIONS

PSD is found in approximately one fifth of patients with clinical bleeding. In patients with PSD, the type and extension of laboratory defect was not associated with bleeding severity.