Type 1 VWD classification revisited: novel insights from combined analysis of the LoVIC and WiN studies

ABSTRACT

There is significant ongoing debate regarding type 1 von Willebrand disease (VWD) defintion. Previous guidelines recommended patients with von Willebrand factor (VWF) levels <30 IU/dL be diagnosed type 1 VWD, whereas patients with significant bleeding and VWF levels from 30 to 50 IU/dL be diagnosed with low VWF. To elucidate the relationship between type 1 VWD and low VWF in the context of age-induced increases in VWF levels, we combined data sets from 2 national cohort studies: 162 patients with low VWF from the Low VWF in Ireland Cohort (LoVIC) and 403 patients with type 1 VWD from the Willebrand in The Netherlands (WiN) studies. In 47% of type 1 VWD participants, VWF levels remained <30 IU/dL despite increasing age. Conversely, VWF levels increased to the low VWF range (30-50 IU/dL) in 30% and normalized (>50 IU/dL) in 23% of type 1 VWD cases. Crucially, absolute VWF antigen (VWF:Ag) levels and increase of VWF:Ag per year overlapped between low VWF and normalized type 1 VWD participants. Moreover, multiple regression analysis demonstrated that VWF:Ag levels in low VWF and normalized type 1 VWD patients would not have been different had they been diagnosed at the same age (β = 0.00; 95% confidence interval, -0.03 to 0.04). Consistently, no difference was found in the prevalence of VWF sequence variants; factor VIII activity/VWF:Ag or VWF propeptide/VWF:Ag ratios; or desmopressin responses between low VWF and normalized type 1 VWD patients. In conclusion, our findings demonstrate that low VWF does not constitute a discrete clinical or pathological entity. Rather, it is part of an age-dependent type 1 VWD evolving phenotype. Collectively, these data have important implications for future VWD classification criteria.

Pharmacokinetic-Pharmacodynamic Modelling in Hemophilia A: Relating Thrombin and Plasmin Generation to Factor VIII Activity After Administration of a VWF/FVIII Concentrate

BACKGROUND

Hemophilia A patients are treated with factor (F) VIII prophylactically to prevent bleeding. In general, dosage and frequency are based on pharmacokinetic measurements. Ideally, an alternative dose adjustment can be based on the hemostatic potential, measured with a thrombin generation assay (TGA), like the Nijmegen hemostasis assay.

OBJECTIVE

The objective of this study was to investigate the predicted performance of a previously developed pharmacokinetic-pharmacodynamic model for FVIII replacement therapy, relating FVIII dose and FVIII activity levels with thrombin and plasmin generation parameters.

METHODS

Pharmacokinetic and pharmacodynamic measurements were obtained from 29 severe hemophilia A patients treated with pdVWF/FVIII concentrate (Haemate P®). The predictive performance of the previously developed pharmacokinetic-pharmacodynamic model was evaluated using nonlinear mixed-effects modeling (NONMEM). When predictions of FVIII activity or TGA parameters were inadequate [median prediction error (MPE) > 20%], a new model was developed.

RESULTS

The original pharmacokinetic model underestimated clearance and was refined based on a two-compartment model. The pharmacodynamic model displays no bias in the observed normalized thrombin peak height and normalized thrombin potential (MPE of 6.83% and 7.46%). After re-estimating pharmacodynamic parameters, EC50 and Emax values were relatively comparable between the original model and this group. Prediction of normalized plasmin peak height was inaccurate (MPE 58.9%).

CONCLUSION

Our predictive performance displayed adequate thrombin pharmacodynamic predictions of the original model, but a new pharmacokinetic model was required. The pharmacodynamic model is not factor specific and applicable to multiple factor concentrates. A prospective study is needed to validate the impact of the FVIII dosing pharmacodynamic model on bleeding reduction in patients.

The spectrum of neutralizing and non-neutralizing anti-FVIII antibodies in a nationwide cohort of 788 persons with hemophilia A

Objectives

Anti-factor VIII (FVIII) antibodies have been reported to exhibit both neutralizing and non-neutralizing characteristics. This is the first study investigating the full spectrum of FVIII-specific antibodies, including non-neutralizing antibodies, very-low titer inhibitors, and inhibitors, in a large nationwide population of persons with hemophilia A of all severities.

Methods

All persons with hemophilia A (mild (FVIII > 5-40 IU/dL)/moderate [FVIII 1-5 IU/dL)/severe (FVIII < 1 IU/dL)] with an available plasma sample who participated in the sixth Hemophilia in the Netherlands study between 2018 and 2019 were included. The presence of anti-FVIII antibodies of the immunoglobulin A, M, and G isotypes and IgG subclasses, along with antibody titer levels, were assessed using direct-binding ELISAs. FVIII specificity was assessed using a competition-based ELISA approach. The inhibitor status was determined using the Nijmegen ultra-sensitive Bethesda assay (NusBA) and the Nijmegen Bethesda assay (NBA).

Results

In total, 788 persons with hemophilia A (336 (42.6%) mild, 123 (15.6%) moderate, 329 (41.8%) severe hemophilia) were included. The median age was 45 years (IQR 24-60), and the majority (50.9%) had over 150 exposure days to FVIII concentrates. Within our population, 144 (18.3%) individuals had non-neutralizing FVIII-specific antibodies, 10 (1.3%) had very low-titer inhibitors (NusBA positive; NBA negative), and 13 (1.6%) had inhibitors (both NusBA and NBA positive). IgG1 was the most abundant FVIII-specific antibody subclass, and the highest titer levels were found for IgG4. In individuals without a reported history of inhibitor development, no clear differences were observed in antibody patterns between those who were minimally or highly exposed to FVIII concentrates. IgG4 subclass antibodies were only observed in persons with a reported history of FVIII inhibitor or in those with a currently detected (very low-titer) inhibitor.

Conclusion

In this cross-sectional study, we identified non-neutralizing antibodies in a relatively large proportion of persons with hemophilia A. In contrast, in our population, consisting of persons highly exposed to FVIII concentrates, (very low-titer) inhibitors were detected only in a small proportion of persons, reflecting a well-tolerized population. Hence, our findings suggest that only a small subpopulation of non-neutralizing FVIII-specific antibodies is associated with clinically relevant inhibitors.

Patients with moderate hemophilia A and B with a severe bleeding phenotype have an increased burden of disease

BACKGROUND

Patients with moderate hemophilia express varying bleeding phenotypes.

OBJECTIVES

To assess the burden of disease in patients with moderate hemophilia and a mild or severe phenotype incorporating the thrombin generation profile.

METHODS

This sub-study of the 6th Hemophilia in the Netherlands study, analyzed data of adults with moderate hemophilia A or B. Patient characteristics and information on bleeding tendency, joint status, and quality of life were obtained from electronic patient files and self-reported questionnaires. A severe bleeding phenotype was defined as an annual bleeding rate ≥5, an annual joint bleeding rate ≥3, and/or the use of secondary/tertiary prophylaxis, and a mild phenotype vice versa. TG was measured with the Nijmegen Hemostasis Assay.

RESULTS

This study included 116 patients: 21% had a severe phenotype of whom 46% used prophylaxis. Patients with a severe phenotype treated on demand reported a higher median annual bleeding rate (7), annual joint bleeding rate (3), and more frequently an impaired joint (77%) than patients with a severe phenotype on prophylaxis (2; 0; 70%) or patients with a mild phenotype (0; 0; 47%). Furthermore, patients with a severe phenotype treated on demand experienced a more decreased quality of life. Despite similar factor activity levels, patients with a severe phenotype had a lower thrombin peak height and thrombin potential (0.7%; 0.06%) than patients with a mild phenotype (21.3%; 46.8%).

CONCLUSION

Patients with moderate hemophilia and a severe phenotype treated on demand displayed a high burden of disease as well as a low thrombin generation profile advocating them toward more intensive prophylactic treatment.

The Nijmegen ultra-sensitive Bethesda Assay detects very low-titer factor VIII inhibitors in patients with congenital and acquired hemophilia A

BACKGROUND

An inhibitor can develop in congenital hemophilia A (HA) patients against exogenous infused factor (F)VIII, whereas in acquired HA (AHA) inhibitors initially develop against endogenous FVIII. Inhibitors can be detected with the Nijmegen Bethesda Assay (NBA), which has an international cut-off level of 0.60 Nijmegen Bethesda Units/mL (NBU/mL). Thereby, very low-titer inhibitors may remain undetected.

AIM

To describe the design and validation of the Nijmegen ultra-sensitive Bethesda Assay (NusBA) for the detection of very low-titer inhibitors.

METHODS

The NusBA is a modification of the NBA in which the ratio of patient plasma to normal pooled plasma is changed from 1:1 to 9:1. Analytical validation was performed according to the CLSI EP10 guideline in order to determine trueness and reproducibility. Clinical validation was performed in two cohorts of congenital HA patients (82 adults) with pharmacokinetic data and four AHA patients. The limit of quantitation (LOQ) was determined by measuring plasma samples spiked with inhibitor levels in the low range (0.05-0.80 NBU/mL).

RESULTS

The LOQ for the NusBA was 0.10 NusBU/mL, with a coefficient of variation of 24.2 %. Seven (8.5 %) congenital HA patients had a positive NusBA result, of which only one was detected with the NBA. There was no correlation between NusBA and FVIII half-life. In three of the AHA patients the NusBA remained positive, when the NBA became negative.

DISCUSSION

The NusBA is able to detect very low-titer FVIII inhibitors of ≥0.10 NBU/mL. Thereby, it may have added value in early inhibitor detection and therapy adjustments in patients with congenital HA and AHA.

High prevalence of heavy menstrual bleeding in women with rare bleeding disorders in the Netherlands: retrospective data from the RBiN study

BACKGROUND

Heavy menstrual bleeding (HMB) is associated with a reduced quality of life and limitations in social and physical functioning. Data on HMB in women with rare bleeding disorders (RBDs), including coagulation factor deficiencies and fibrinolytic disorders, are scarce.

OBJECTIVES

To analyze the prevalence, severity, and treatment of HMB in Dutch women with an RBD.

METHODS

The Rare Bleeding Disorders in the Netherlands (RBiN) study included 263 patients with an RBD from all 6 hemophilia treatment centers (October 2017-November 2019). In this analysis, data of 111 women aged ≥16 years were studied. According to the International Society on Thrombosis and Haemostasis bleeding assessment tool, HMB symptoms were scored from 0 (no/trivial) to 4 (severe symptoms requiring medical intervention). HMB was defined as a score ≥1. Age at RBD diagnosis was extracted from patient files.

RESULTS

HMB was reported by 80% of women (89/111) and was more prevalent in women with a fibrinolytic disorder (33/35; 94%) than in women with a coagulation factor deficiency (56/76; 74%) (P = .011). Of the 89 women with HMB, 82% (n = 73) ever required treatment. Multiple treatment modalities were frequently used, both in severe and mild deficiencies. Hormonal treatment was mostly used (n = 64; 88%), while antifibrinolytics were prescribed less frequently (n = 18; 25%). In women with HMB since menarche (n = 61; 69%), median age at RBD diagnosis was 28 years (IQR, 14-41).

CONCLUSION

HMB is common in women with RBDs. Women with mild deficiencies also frequently reported HMB. Only a minority of women were treated with hemostatic agents. A significant diagnostic delay was observed after the onset of HMB symptoms.

Transition readiness among adolescents and young adults with haemophilia in the Netherlands: Nationwide questionnaire study

INTRODUCTION

Care for adolescents with haemophilia is transferred from paediatric to adult care around the age of 18 years. Transition programs help to prepare adolescents for this transfer and prevent declining treatment adherence. Evaluating transition readiness may identify areas for improvement.

OBJECTIVE

Assess transition readiness among Dutch adolescents and young adults with haemophilia, determine factors associated with transition readiness, and identify areas of improvement in transition programs.

METHODS

All Dutch adolescents and young adults aged 12-25 years with haemophilia were invited to participate in a nationwide questionnaire study. Transition readiness was assessed using multiple-choice questions and was defined as being ready or almost ready for transition. Potential factors associated with transition readiness were investigated, including: socio-demographic and disease-related factors, treatment adherence, health-related quality of life, and self-efficacy.

RESULTS

Data of 45 adolescents and 84 young adults with haemophilia (47% with severe haemophilia) were analyzed. Transition readiness increased with age, from 39% in 12-14 year-olds to 63% in 15-17 year-olds. Nearly all post-transition young adults (92%, 77/84) reported they were ready for transition. Transition readiness was associated with treatment adherence, as median VERITAS-Pro treatment adherence scores were worse in patients who were not ready (17, IQR 9-29), compared to those ready for transition (11, IQR 9-16). Potential improvements were identified: getting better acquainted with the adult treatment team prior to transition and information on managing healthcare costs.

CONCLUSIONS

Nearly all post-transition young adults reported they were ready for transition. Improvements were identified regarding team acquaintance and preparation for managing healthcare costs.

High prevalence of postpartum hemorrhage in women with rare bleeding disorders in the Netherlands: retrospective data from the RBiN study

BACKGROUND

Women with rare bleeding disorders (RBDs), including coagulation factor deficiencies and fibrinolytic disorders, may have a higher risk of postpartum hemorrhage (PPH). Information on this patient category is lacking in the existing PPH guidelines because data on PPH in patients with RBDs are scarce.

OBJECTIVE

To describe the prevalence of PPH in women with an RBD and evaluate the use of peripartum hemostatic prophylaxis.

METHODS

In the Rare Bleeding Disorders in the Netherlands (RBiN) study, patients with RBDs (n = 263) were included from all 6 Dutch hemophilia treatment centers. Patient-reported information on delivery, peripartum hemostatic prophylaxis, and occurrence of PPH was collected retrospectively. If available, information about the precise volume of postpartum blood loss was extracted from electronic patient files. PPH was defined as blood loss ≥500 mL (World Health Organization guideline).

RESULTS

A total of 244 pregnancies, including 193 livebirths, were reported by 85 women. A considerable proportion of these women experienced PPH, ranging from 30% in factor V deficiency to 100% in hyperfibrinolysis. Overall, PPH was reported in 44% of deliveries performed with and 53% of deliveries performed without administration of peripartum hemostatic prophylaxis. Blood loss was significantly higher in deliveries without administration of hemostatic prophylaxis (median 1000 mL) compared to deliveries with administration of prophylaxis (median 400 mL) (p = 0.011). Patients with relatively mild deficiencies also frequently experienced PPH when peripartum hemostatic prophylaxis was omitted.

CONCLUSION

PPH is common in rare coagulation factor deficiencies, both severe and mild, and fibrinolytic disorders, especially when peripartum prophylactic hemostatic treatment was not administered. The use of prophylactic hemostatic treatment was associated with less postpartum blood loss.

Colorectal cancer screening in patients with inherited bleeding disorders: high cancer detection rate in hemophilia patients

BACKGROUND

The population-based colorectal cancer (CRC) screening program in individuals aged 55 to 75 years in the Netherlands uses fecal immunochemical testing (FIT), to detect hemoglobin in feces, followed by colonoscopy in individuals with a positive FIT.

OBJECTIVES

The objectives of this study are to assess the false-positive rate, detection rate, and positive predictive value of FIT for CRC and advanced adenoma (AA) in patients with Von Willebrand disease (VWD) or hemophilia.

METHODS

We performed a multicenter, nationwide cross-sectional study embedded in 2 nationwide studies on VWD and hemophilia in the Netherlands.

RESULTS

In total, 493 patients with hemophilia (n = 329) or VWD (n = 164) were included, of whom 351 patients participated in the CRC screening program (71.2%). FIT positivity and false-positive rate in patients with hemophilia and VWD were significantly higher than those in the general population (14.8% vs. 4.3%, p < .001 and 10.3% vs. 2.3%, p <.001, respectively). In patients with hemophilia, the detection rate of CRC/AA was significantly higher than that in the general male population (4.5% vs. 1.8%, p = .02), and the positive predictive value of FIT for CRC/AA was comparable (32.3% vs. 39.7%, n.s.). In patients with VWD, the detection rate was similar to that of the general population (0.8% vs. 1.4%, n.s.), whereas the positive predictive value was significantly lower than that in the general population (6.3% vs. 36.8%, p = .02).

CONCLUSION

This study indicates that despite a high false-positive rate of FIT in patients with inherited bleeding disorders, the detection rate of CRC and/or AA in hemophilia patients is high. FIT performs different in patients with hemophilia or VWD compared with the general population.

Thrombin generation assays to personalize treatment in bleeding and thrombotic diseases

Treatment of bleeding and thrombotic disorders is highly standardized and based on evidence-based medicine guidelines. These evidence-based treatment schemes are well accepted but may lead to either insufficient treatment or over-dosing, because the individuals' hemostatic properties are not taken into account. This can potentially introduce bleeding or thrombotic complications in individual patients. With the incorporation of pharmacokinetic (PK) and pharmacodynamic (PK-PD) parameters, based on global assays such as thrombin generation assays (TGAs), a more personalized approach can be applied to treat either bleeding or thrombotic disorders. In this review, we will discuss the recent literature about the technical aspects of TGAs and the relation to diagnosis and management of bleeding and thrombotic disorders. In patients with bleeding disorders, such as hemophilia A or factor VII deficiency, TGAs can be used to identify patients with a more severe bleeding phenotype and also in the management with non-replacement therapy and/or bypassing therapy. These assays have also a role in patients with venous thrombo-embolism, but the usage of TGAs in patients with arterial thrombosis is less clear. However, there is a potential role for TGAs in the monitoring of (long-term) antithrombotic therapy, for example with the use of direct oral anticoagulants. Finally this review will discuss controversies, limitations and knowledge gaps in relation to the introduction of TGAs to personalize medicine in daily medical practice.

Validation of the pedHALshort and HALshort in Dutch children and adults with haemophilia

INTRODUCTION

The Haemophilia Activities List (HAL) and paediatric HAL assess self-reported limitations in various daily activities. To reduce patient burden, shorter versions of the pedHAL (22 items) and HAL (18 items) have been developed.

AIM

This study aimed to determine the agreement between the pedHAL/HAL_full and pedHAL/HAL_short and construct validity and internal consistency of the pedHAL_/ HAL_short in persons with haemophilia (PWH).

METHODS

A cross-sectional secondary analysis of the Hemophilia in the Netherlands-6 national survey was performed. Adult and paediatric PWH completed the original pedHAL/HAL_full , from which pedHAL_/ HAL_short were derived. Score differences between the original and short versions were calculated. Construct validity was studied by testing hypotheses regarding the relationship of the pedHAL/HAL_short with the pedHAL/HAL_full , Haemophilia & Exercise Project Test-Questionnaire (HEP-Test-Q), Canadian Haemophilia Outcomes-Kids' Life Assessment Tool (CHO-KLAT) and RAND 36-item Health Survey (RAND-36) (convergent/discriminant validity) as well as its ability to discriminate between subgroups (known-group validity). Internal consistency was assessed with Cronbach's α.

RESULTS

We included 113 children (median 10y [range 4-17], 53% severe haemophilia) and 691 adults (median 51y [range 18-88], 35% severe). Scores of the pedHAL/HAL_full and pedHAL/HAL_short were similar with high correlations (>0.9). Construct validity was confirmed for the pedHAL/HAL_short . The HAL_short was able to discriminate between different disease severities and ages. Cronbach's α of the pedHAL/HAL_short was 0.95-0.97.

CONCLUSION

This study confirmed the agreement between the pedHAL/HAL_full and the pedHAL/HAL_short and the construct validity of the pedHAL/HAL_short . The next step is to study construct validity of the pedHAL/HAL_short when administered as short forms.

Socioeconomic participation of persons with hemophilia: Results from the sixth hemophilia in the Netherlands study

Background and objectives

Treatment availability and comprehensive care have resulted in improved clinical outcomes for persons with hemophilia. Recent data on socioeconomic participation in the Netherlands are lacking. This study assessed participation in education, in the labor market, and social participation for persons with hemophilia compared with the general male population.

Methods

Dutch adults and children (5–75 years) of all hemophilia severities (n = 1009) participated in a questionnaire study that included sociodemographic, occupational, and educational variables. Clinical characteristics were extracted from electronic medical records. General population data were extracted from Statistics Netherlands. Social participation was assessed with the PROMIS Ability to Participate in Social Roles and Activities short form, with a minimal important difference set at 1.0.

Results

Data from 906 adults and children were analyzed. Participation in education of 20 to 24 year olds was 68% (general male population: 53%). Educational attainment was higher compared with Dutch males, especially for severe hemophilia. Absenteeism from school was more common than in the general population. The employment‐to‐population ratio and occupational disability were worse for severe hemophilia than in the general population (64.3% vs. 73.2% and 14.7% vs. 4.8%, respectively), but similar for nonsevere hemophilia. Unemployment was 5.4% (general male population: 3.4%). Absenteeism from work was less common (38% vs. 45.2%). Mean PROMIS score was similar to or higher than in the general population (54.2; SD 8.9 vs. 50; SD 10).

Conclusion

Socioeconomic participation of persons with nonsevere hemophilia was similar to the general male population. Some participation outcomes for persons with severe hemophilia were reduced.

IRIDA Phenotype in TMPRSS6 Monoallelic-Affected Patients: Toward a Better Understanding of the Pathophysiology

Iron-refractory iron deficiency anemia (IRIDA) is an autosomal recessive inherited form of iron deficiency anemia characterized by discrepantly high hepcidin levels relative to body iron status. However, patients with monoallelic exonic TMPRSS6 variants have also been reported to express the IRIDA phenotype. The pathogenesis of an IRIDA phenotype in these patients is unknown and causes diagnostic uncertainty. Therefore, we retrospectively summarized the data of 16 patients (4 men, 12 women) who expressed the IRIDA phenotype in the presence of only a monoallelic TMPRSS6 variant. Eight unaffected relatives with identical exonic TMPRSS6 variants were used as controls. Haplotype analysis was performed to assess the (intra)genetic differences between patients and relatives. The expression and severity of the IRIDA phenotype were highly variable. Compared with their relatives, patients showed lower Hb, MCV, and TSAT/hepcidin ratios and inherited a different wild-type allele. We conclude that IRIDA in monoallelic TMPRSS6-affected patients is a phenotypically and genotypically heterogeneous disease that is more common in female patients. We hypothesize that allelic imbalance, polygenetic inheritance, or modulating environmental factors and their complex interplay are possible causes. This explorative study is the first step toward improved insights into the pathophysiology and improved diagnostic accuracy for patients presenting with IRIDA and a monoallelic exonic TMPRSS6 variant.

Thrombin generation for monitoring hemostatic therapy in hemophilia A: A narrative review

Patients with severe hemophilia A (HA) have an increased risk of spontaneous and trauma-related bleeding because of a congenital absence of factor VIII (FVIII). Most severe HA patients use prophylactic FVIII concentrate, the effect of which can be monitored with FVIII activity level measurement. However, FVIII activity level is less valuable in predicting the potential clinical bleeding risk. Some patients still experience breakthrough bleeds despite adequate FVIII trough levels, whereas others do not bleed with trough levels below threshold. This difference may be caused by inter-individual differences in pro- and anticoagulant factors, the so-called hemostatic balance. Thrombin generation assays (TGAs) measure the hemostatic balance as a whole. Thereby, the TGAs may be a better tool in the guidance and monitoring of treatment in HA patients. In addition, TGAs offer the opportunity to determine the response to bypassing agents and treatment with non-factor replacement therapy, in which FVIII activity assays are not suitable for monitoring. This review summarizes the current knowledge about monitoring different HA treatment modalities by TGA, as a single treatment option and when used in a concomitant fashion.

Treatment of patients with rare bleeding disorders in the Netherlands: Real-life data from the RBiN study

BACKGROUND

Patients with rare inherited bleeding disorders (RBDs) exhibit hemorrhagic symptoms, varying in type and severity, often requiring only on-demand treatment. Prolonged bleeding after invasive procedures is common. Adequate peri-procedural therapy may reduce this bleeding risk.

OBJECTIVE

To describe general treatment plans of RBD patients and evaluate the use of peri-procedural hemostatic therapy.

METHODS

In the Rare Bleeding Disorders in the Netherlands (RBiN) study, RBD patients from all six Dutch Hemophilia Treatment Centers were included. General treatment plans were extracted from patient files. Patients with a dental or surgical procedure in their history were interviewed about use of peri-procedural treatment and bleeding complications.

RESULTS

Two-hundred sixty-three patients with a rare coagulation factor deficiency or fibrinolytic disorder were included. Eighty-four percent had a documented general treatment plan. General treatment plans of patients with the same RBD were heterogeneous, particularly in factor XI deficiency. Overall, 308 dental and 408 surgical procedures were reported. Bleeding occurred in 50% of dental and 53% of surgical procedures performed without hemostatic treatment and in 28% of dental and 19% of surgical procedures performed with hemostatic treatment. Not only patients with severe RBDs, but also patients with mild deficiencies, experienced increased bleeding without proper hemostatic treatment.

CONCLUSION

Large heterogeneity in general treatment plans of RBD patients was found. Bleeding after invasive procedures was reported frequently, both before and after RBD diagnosis, irrespective of factor activity levels and particularly when peri-procedural treatment was omitted. Improved guidelines should include uniform recommendations for most appropriate hemostatic products per RBD and emphasize the relevance of individual bleeding history.

Platelet degranulation and bleeding phenotype in a large cohort of Von Willebrand disease patients

Von Willebrand disease (VWD) is a bleeding disorder caused by quantitative (type 1 or 3) or qualitative (type 2A/2B/2M/2N) defects of circulating von Willebrand factor (VWF). Circulating VWF levels not always fully explain bleeding phenotypes, suggesting a role for alternative factors, like platelets. Here, we investigated platelet factor 4 (PF4) in a large cohort of patients with VWD. PF4 levels were lower in type 2B and current bleeding phenotype was significantly associated with higher PF4 levels, particularly in type 1 VWD. Based on our findings we speculate that platelet degranulation and cargo release may play a role across VWD subtypes.

Fibrinolytic assays in bleeding of unknown cause: Improvement in diagnostic yield

Introduction

Aim

Methods

Results

Discussion

Von Willebrand disease type 2M: Correlation between genotype and phenotype

BACKGROUND

An appropriate clinical diagnosis of von Willebrand disease (VWD) can be challenging because of a variable bleeding pattern and laboratory phenotype. Genotyping is a powerful diagnostic tool and may have an essential role in the diagnostic field of VWD.

OBJECTIVES

To unravel the clinical and laboratory heterogeneity of genetically confirmed VWD type 2M patients and to investigate their relationship.

METHODS

Patients with a confirmed VWD type 2M genetic variant in the A1 or A3 domain of von Willebrand factor (VWF) and normal or only slightly aberrant VWF multimers were selected from all subjects genotyped at the Radboud university medical center because of a high suspicion of VWD. Bleeding scores and laboratory results were analyzed.

RESULTS

Fifty patients had a clinically relevant genetic variant in the A1 domain. Median bleeding score was 5. Compared with the nationwide Willebrand in the Netherlands study type 2 cohort, bleeding after surgery or delivery was reported more frequently and mucocutaneous bleedings less frequently. Median VWF activity/VWF antigen (VWF:Act/VWF:Ag) ratio was 0.32, whereas VWF collagen binding activity/VWF antigen (VWF:CB/VWF:Ag) ratio was 0.80. Variants in the A3 domain were only found in two patients with low to normal VWF:Act/VWF:Ag ratios (0.45, 1.03) and low VWF:CB/VWF:Ag ratios (0.45, 0.63).

CONCLUSION

Genetically confirmed VWD type 2M patients have a relatively mild clinical phenotype, except for bleeding after surgery and delivery. Laboratory phenotype is variable and depends on the underlying genetic variant. Addition of genotyping to the current phenotypic characterization may improve diagnosis and classification of VWD.

Patient-reported outcomes in autosomal inherited bleeding disorders: A systematic literature review

Aim

Currently, it is unknown which patient‐reported outcomes are important for patients with autosomal inherited bleeding disorders. Therefore, the purpose of this study is to systematically review the available literature assessing patient‐reported outcomes and their measurement methods in autosomal inherited bleeding disorders.

Methods

The Embase, Medline ALL, Web of Science Core Collection, Cochrane Central Register of Controlled Trails and Google Scholar databases were searched from inception until 14 August 2020. Studies on patient‐reported outcomes in patients with von Willebrand disease, inherited platelet function disorders and coagulation factor deficiencies were included.

Results

Twenty‐one articles met the inclusion criteria. Three studies were assessed as having poor quality, and therefore a high risk of bias. Nineteen studies had fair quality rating. Different measurements methods were used, ranging from predefined to self‐developed questionnaires. The majority of included studies focused on von Willebrand disease. Patients with von Willebrand disease reported lower health‐related quality of life compared to the general population. Overall, this trend was especially visible in the following domains: vitality, physical and social functioning and pain. Women with inherited bleeding disorders scored lower on health‐related quality of life compared to men, especially women with heavy menstrual bleeding. Patients with joint bleeds or heavy menstrual bleeding reported an increased level of pain.

Conclusion

Patients with autosomal inherited bleeding disorders report lower health related quality of life, especially those with joint bleeds or heavy menstrual bleeding. Numerous measurement methods are used in patients with autosomal inherited bleeding disorders, highlighting the need for studies using established, standardized measurement methods.

Social participation is reduced in type 3 Von Willebrand disease patients and in patients with a severe bleeding phenotype

INTRODUCTION

The negative impact of haemophilia on social participation is well established in previous studies, however, the impact of Von Willebrand disease (VWD) on social participation has not been studied.

AIM

To compare the social participation of a large cohort of VWD patients in the Netherlands with the general Dutch population. In addition, to identify factors associated with social participation in VWD.

METHODS

Patients participating in the "Willebrand in the Netherlands" study completed an extensive questionnaire on educational level, absenteeism from school or work, and occupational disabilities.

RESULTS

Seven-hundred and eighty-eight VWD patients were included (mean age 38.9 years, 59.5% females), of whom 136 children < 16 years. Adult patients with type 3 VWD more often had a low educational level (52.9%) compared to type 1 (40.2%), type 2 VWD (36.8%) and the general population (36.4%) (p = .005). Moreover, in patients aged ≥16 years the days lost from school and/or work in the year prior to study inclusion differed significantly between the VWD types (p = .011). Using negative binomial regression analysis, the occurrence of bleeding episodes requiring treatment in the year preceding study inclusion was significantly associated with the number of days lost from school and/or work among patients aged ≥16 years. Multivariable logistic regression analysis showed that a higher total bleeding score, older age and presence of at least one comorbidity were significantly associated with occupational disability in patients aged ≥16 years.

CONCLUSION

Our study shows that social participation was lower in type 3 VWD and VWD patients with a more severe bleeding phenotype.

Combining factor VIII levels and thrombin/plasmin generation: a population pharmacokinetic-pharmacodynamic model for patients with hemophilia A

Aims

Prophylactic treatment of haemophilia A patients with factor VIII (FVIII) concentrate focuses on maintaining a minimal trough FVIII activity level to prevent bleeding. However, due to differences in bleeding tendency, the pharmacokinetic (PK)‐guided dosing approach may be suboptimal. An alternative approach could be the addition of haemostatic pharmacodynamic (PD) parameters, reflecting a patient's unique haemostatic balance. Our aim was to develop a population PK/PD model, based on FVIII activity levels and Nijmegen Haemostasis Assay (NHA) patterns, a global haemostatic assay that measures thrombin/plasmin generation simultaneously.

Methods

PK/PD measurements were collected from 30 patients treated with standard half‐life FVIII concentrate. The relationship between FVIII activity levels and the thrombin/plasmin generation parameters (thrombin potential, thrombin peak height and plasmin peak height), were described by sigmoidal E_max functions.

Results

The obtained EC₅₀ value was smallest for the normalized thrombin potential (11.6 IU/dL), followed by normalized thrombin peak height (56.6 IU/dL) and normalized plasmin peak height (593 IU/dL), demonstrating that normalized thrombin potential showed 50% of the maximal effect at lower FVIII activity levels. Substantial inter‐individual variability in the PD parameters, such as EC₅₀ of thrombin potential (86.9%) was observed, indicating that, despite similar FVIII activity levels, haemostatic capacity varies significantly between patients.

Conclusion

These data suggest that dosing based on patients' individual PK/PD parameters may be beneficial over dosing solely on individual PK parameters. This model could be used as proof‐of‐principle to examine the application of PK/PD‐guided dosing. However, the relation between the PD parameters and bleeding has to be better defined.

Hepatitis C virus in hemophilia: Health-related quality of life after successful treatment in the sixth Hemophilia in the Netherlands study

INTRODUCTION

Persons with hemophilia and hepatitis C virus (HCV) infection have a lower health-related quality of life (HRQoL) than those never HCV infected. However, it is unknown whether HRQoL after HCV eradication is comparable to individuals never HCV infected. We aimed to compare HRQoL between HCV-cured and never chronically HCV-infected persons with hemophilia.

METHODS

All persons with hemophilia in the Netherlands were invited for a nationwide study conducted in 2018-2019. For the current analysis, participants born before 1992 with data on HRQoL and HCV status were included. HCV status was collected from medical records. HRQoL was measured by RAND-36 questionnaire, with a minimally important difference set at 4.0 points. Multivariable linear regression was used to adjust for age, hemophilia severity, HIV status, and self-reported joint impairment.

RESULTS

In total, 486 persons were eligible; 180 were HCV cured and 306 never chronically HCV infected. Compared with those never HCV infected, HCV-cured individuals were older (57 vs. 53 years), more often had severe hemophilia (67% vs. 21%), and reported more impaired joints (median 3 vs. 0). Compared with those never HCV infected, adjusted RAND-36 domain scores of HCV-cured individuals cured were lower on all RAND-36 domains except Pain, ranging from a difference of 4.5 (95% CI, -8.8 to -0.3) for Physical functioning to 11.3 (95% CI, -19.4 to -3.1) for Role limitations due to physical problems.

CONCLUSION

Despite effective HCV treatment, HRQoL of HCV-cured persons with hemophilia is still lower than HRQoL of those never chronically HCV-infected on all RAND-36 domains. This implies that careful psychosocial follow-up and support are indicated.

Validation of PROMIS Profile-29 in adults with hemophilia in the Netherlands

BACKGROUND

The Patient-Reported Outcomes Measurement Information System (PROMIS) Profile-29 questionnaire is widely used worldwide, but it has not yet been validated in the Netherlands, nor in persons with hemophilia.

OBJECTIVE

To validate the Dutch-Flemish version of the PROMIS-29 Profile v2.01 in adults with hemophilia.

METHODS

Dutch males with hemophilia (all severities) completed questionnaires that contained sociodemographic and clinical characteristics, the PROMIS-29, RAND-36, and the Hemophilia Activities List (HAL). Structural validity of each subscale was assessed with confirmatory factor analysis (CFA). Internal consistency was calculated for each subscale with sufficient model fit in CFA. Construct validity was assessed by testing hypotheses about (1) correlations of each PROMIS-29 subscale with corresponding scales of RAND-36 and domains of HAL, and (2) mean differences in T-scores between subgroups with different hemophilia severities, self-reported joint impairment, and HIV infection status. We considered ≥75% of data in accordance with the hypotheses evidence for construct validity.

RESULTS

In total, 770 persons with hemophilia participated in this cross-sectional study. CFA revealed sufficient structural validity for five subscales: Physical Function, Depression, Sleep Disturbance, Ability to Participate in Social Roles and Activities, and Pain Interference. Internal consistency was high and Cronbach's alpha ranged from 0.79 for Sleep Disturbance to 0.96 for Pain Interference. Differences between clinical subgroups were in the expected direction. Construct validity was confirmed for Physical Function, Anxiety, Depression, Fatigue, Sleep Disturbance, and Pain Intensity.

CONCLUSION

This study revealed sufficient evidence for structural validity, internal consistency, and construct validity for most PROMIS Profile-29 subscales among people with hemophilia in the Netherlands.

Health and treatment outcomes of patients with hemophilia in the Netherlands, 1972-2019

INTRODUCTION

We conducted six cross-sectional nationwide questionnaire studies among all patients with hemophilia in the Netherlands from 1972 until 2019 to assess how health outcomes have changed, with a special focus on patients >50 years of age.

METHODS

Data were collected on patient characteristics, treatment, (joint) bleeding, joint impairment, hospitalizations, human immunodeficiency virus and hepatitis C infections, and general health status (RAND-36).

RESULTS

In 2019, 1009 patients participated, of whom 48% had mild, 15% moderate, and 37% severe hemophilia. From 1972 to 2019, the use of prophylaxis among patients with severe hemophilia increased from 30% to 89%. Their median annual bleeding rate decreased from 25 to 2 bleeds. Patients with severe hemophilia aged <16 years reported joint impairment less often over time, but in those aged >40 years joint status did not improve. In 2019, 5% of all 1009 patients were positive for the human immunodeficiency virus. The proportion of patients with an active hepatitis C infection drastically decreased from 45% in 2001 to 2% in 2019 due to new anti-hepatitis C treatment options. Twenty-five percent had significant liver fibrosis even after successful therapy. Compared to the general male population, patients aged >50 years reported much lower scores on the RAND-36, especially on physical functioning.

DISCUSSION/CONCLUSION

Our study shows that increased use of prophylactic treatment and effective hepatitis C treatment have improved joint health and nearly eradicated hepatitis C infection in patients with hemophilia in the Netherlands. However, patients still suffer from hemophilia-related complications, especially patients aged >50 years.

Adherence to prophylaxis and its association with activation of self-management and treatment satisfaction

INTRODUCTION

Prophylactic replacement therapy (prophylaxis) in patients with haemophilia (PWH) requires lifelong, frequent (self)infusions. Prophylaxis effectiveness depends on adherence, and the drivers of treatment adherence among PWH are unclear.

AIM

To quantify prophylaxis adherence and associations between adherence and patients' treatment attitudes and satisfaction in a large cohort of children and adults with haemophilia.

METHODS

In a nationwide, cross-sectional, questionnaire-based study, PWH with complete information currently using prophylaxis were selected. Validated Hemophilia Regimen Treatment Adherence Scale-Prophylaxis (VERITAS-Pro; normalised score range: 0-100, optimum 0) measured treatment adherence; the Patient Activation Measure (PAM-13; total score range 0-100, optimum 100) measured activation of self-management; Hemophilia Patient Satisfaction Scale (Hemo-Sat; range 0-100, optimum 0) measured treatment satisfaction. Groups were compared according to age (children: <12 years; adolescents: 12-18 years; adults >18 years) and adherence levels using non-parametric tests, and correlations were assessed using Spearman's rho.

RESULTS

Among 321 participants (median age 33 years, interquartile range [IQR]:15-54 years), adherence was high (median VERITAS-Pro total score 17, 89% adherent) but worsened with age, with median scores of 5, 14 and 20 in children, adolescents, adults, respectively (p < .001). Attitudes towards treatment (median 66 vs. 68) participants and treatment satisfaction (12 vs. 10) were similar between adherent and non-adherent patients. The VERITAS-Pro total score was moderately correlated with PAM-13 (r = .41) but not with Hemo-Sat (r = -.11).

DISCUSSION

Prophylaxis adherence was high (89%) but decreased significantly with age and was not correlated with treatment attitude or treatment satisfaction.

Similar sports participation as the general population in Dutch persons with haemophilia; results from a nationwide study

Introduction

Although sports participation is advocated in people with haemophilia (PWH), detailed data concerning sports participation in Dutch PWH is lacking.

Aim

to assess sports participation in Dutch PWH (6‐65 years) compared to the Dutch general population (GP).

Methods

Data from a nationwide, cross‐sectional study in PWH were analysed. Sports participation (type, duration, frequency) was assessed by the Modifiable Activities Questionnaire (MAQ), limitations in activities using the (Paediatric) Haemophilia Activities List ((Ped)HAL). Sports in the two highest categories according to the National Hemophilia Foundation classification were considered high‐risk sports. Groups were compared using Chi‐square testing.

Results

A total of 524 Adult PWH (median age: 45 (IQR: 30–55); 37% severe) and 126 paediatric PWH (median age: 11 (IQR: 8–14); 52% severe) were included. Sports participation was higher in adults (70%) than the GP (58%) and similar to the GP in children (PWH: 68%, GP: 72%). High‐risk sports participation decreased with age in PWH: from 65% (6‐12 years) to 17% (50‐65 years), which was also observed in the GP. Sports participation in children was independent of severity (non‐severe: 67% vs. severe: 65%; P = 0.97), but not in adults (non‐severe: 75%, severe: 62%; P < 0.01). Non‐severe PWH played more high‐risk sports than severe PWH: children at 65% vs. 48% (P = 0.05), adults at 25% vs. 15% (P = 0.07).

Discussion

These results suggest that sports participation in PWH was comparable to the GP. Sports participation was dependent of haemophilia severity in adults. Children were more involved in high‐risk sports than adults. More studies on sports‐related injury‐risk are needed for adequate counselling.

Mortality, life expectancy, and causes of death of persons with hemophilia in the Netherlands 2001-2018

BACKGROUND

Treatment of patients with hemophilia has advanced over the past decades, but it is unknown whether this has resulted in a normal life expectancy in the Netherlands.

OBJECTIVE

This observational cohort study aimed to assess all-cause and cause-specific mortality in patients with hemophilia in the Netherlands between 2001 and 2018 and to compare mortality and life expectancy with previous survival assessments from 1973 onward.

PATIENTS/METHODS

All 1066 patients with hemophilia who participated in a nationwide survey in 2001 were followed until July 2018.

RESULTS

Information on 1031 individuals (97%) was available, of whom 142 (14%) deceased during follow-up. Compared with the general Dutch male population, mortality of patients with hemophilia was still increased (standardized mortality ratio: 1.4, 95% confidence interval: 1.2-1.7). Intracranial bleeding and malignancies were the most common causes of death. Estimated median life expectancy of patients with hemophilia was 77 years, 6 years lower than the median life expectancy of the general Dutch male population (83 years). Over the past 45 years, death rates of patients with hemophilia have consistently decreased, approaching the survival experience of the general population. Over the past decades, mortality due to human immunodeficiency virus and hepatitis C virus infections has decreased, death due to intracranial hemorrhages has increased, and death due to ischemic heart disease has remained consistently low over time.

CONCLUSIONS

Survival in patients with hemophilia in the Netherlands has improved over time but is still lower than that of the general population.

The potential of individualized dosing of ravulizumab to improve patient-friendliness of paroxysmal nocturnal haemoglobinuria treatment at reduced costs

Ravulizumab is a very expensive complement C5‐inhibitor for the treatment of paroxysmal nocturnal haemoglobinuria, with a fixed‐dosing interval of 8 weeks. For lifelong treatment, a cost‐effective and patient‐friendly dosing strategy is preferred. We therefore explored alternative ravulizumab dosing regimens in silico based on the thorough dose‐finding studies of the manufacturer. Extending the interval to 10 weeks or individually extending the interval to a mean of 12.8 weeks based on pharmacokinetic monitoring resulted in noninferior efficacy in terms of lactate dehydrogenase normalization, with drug cost savings up to 37%. We here show the potential of individualized ravulizumab dosing to improve patient‐friendliness at reduced costs.

Bleeding severity in patients with rare bleeding disorders: real-life data from the RBiN study

Patients with hereditary rare bleeding disorders (RBDs) present with diverse hemorrhagic symptoms. Correlation between factor activity levels and clinical bleeding severity is poor for most RBDs. Threshold factor activity levels have been previously described in relation to bleeding severity but have not yet been validated. The Rare Bleeding Disorders in the Netherlands (RBiN) study is a nationwide cross-sectional study of patients registered in all 6 Dutch Haemophilia Treatment Centers with a known RBD and who are age 1 to 99 years. Bleeding scores were determined, and laboratory and clinical data were extracted from patient files. In all, 263 patients were included, of whom 202 (77%) attended the scheduled study visit. The median International Society of Thrombosis and Haemostasis (ISTH) bleeding assessment tool (BAT) score was 9. Correlations between baseline factor activity levels and ISTH BAT scores were strong for deficiencies in factor II (FII) (r = -0.792) and FX (r = -0.838) and were moderate for deficiencies of fibrinogen (r = -0.683), FV (r = -0.623), FVII (r = -0.516), FXIII (r = -0.516), and α2-antiplasmin (r = -0.594). There was no correlation for FXI deficiency (r = -0.218). The RBD BAT identified more women (94% vs 83%) and children (100% vs 71%) with an RBD than the ISTH BAT did. Importantly, 48% of patients had more severe bleeding than predicted for their baseline factor activity level. In addition, 34% of patients were predicted to be asymptomatic, but they actually had grade 2 (31%) or 3 (3%) bleeding. Bleeding severity in patients with RBDs is more pronounced than previously anticipated. The previously determined threshold factor activity levels to ensure no (spontaneous) bleeding in patients with an RBD are inaccurate. This trial was registered at www.clinicaltrials.gov as #NCT03347591.

Pregnancy outcome in afibrinogenemia: Are we giving enough fibrinogen concentrate? A case series

Congenital afibrinogenemia is a rare autosomal recessive disorder associated with an increased risk of hemorrhage, thrombosis, and obstetric complications. This case series of 4 pregnancies in 2 related patients seeks to address the key clinical question of the necessary doses of fibrinogen concentrate during pregnancy and puerperium. One pregnancy without the prophylactic use of fibrinogen concentrate resulted in spontaneous abortion. The second pregnancy was complicated by a subchorionic hematoma despite the prophylactic administration of fibrinogen concentrate to maintain the plasma trough levels at ≥0.6 g/L. Labor was complicated by postpartum hemorrhage with a blood loss volume of 1480 cc. Two weeks later, the patient presented with postpartum thrombosis. The other 2 pregnancies were uncomplicated with fibrinogen trough levels ≥1.0 g/L during pregnancy and ≥1.5 g/L during labor. These cases illustrate that during pregnancy, patients may benefit from fibrinogen trough levels ≥1.0 g/L. In addition, the increased risk of postpartum thrombosis with prolonged fibrinogen supplementation warrants personalized postpartum advice that is guided by postpartum blood loss.

Diagnostic work up of patients with increased bleeding tendency

Introduction

The diagnostic trajectory of patients with increased bleeding tendency can be very costly and time‐consuming. In addition, previous studies have shown that half of these patients remain without final diagnosis despite all efforts.

Aim

This study aimed to improve insight into the current diagnostic process of these patients.

Methods

A total of 117 adult patients, referred to an academic hospital because of being suspected to have an increased bleeding tendency, were included. Different parameters were compared between patients receiving final diagnosis, patients without final diagnosis but a high Tosetto bleeding assessment tool (BAT) score (classified as bleeding of unknown cause, or BUC) and a control group consisting of patients without final diagnosis and a low BAT score.

Results

The BAT score was significantly higher in patients in the BUC group as compared to patients reaching final diagnosis (8.1 vs 4.9). Interestingly, the two subcategories most prevalently increased were surgery and post‐partum haemorrhage‐associated bleeding (surgery: 2.1 vs 1.1; post‐partum haemorrhage: 0.7 vs 0.0). Laboratory screening results were more often abnormal in patients reaching final diagnosis compared to patients remaining without diagnosis and a high BAT score (n = 32 (78%) vs n = 14 (46%), 95% CI 1.5‐12), especially concerning the PFA (=27 (66%) vs n = 10 (33%), 95% CI 1.4‐10) and von Willebrand factor activity levels (n = 11 (27%) vs n = 1 (3%), 95% CI 1.3‐91).

Conclusion

Isolated high bleeding score on surgical or post‐partum bleeding correlates with a lower chance of receiving final diagnosis. Withholding extensive haemostatic testing should be considered. Better screening and confirmative haemostatic assays are still needed.

Thrombin and plasmin generation in patients with plasminogen or plasminogen activator inhibitor type 1 deficiency

INTRODUCTION

Deficiencies of plasminogen and plasminogen activator inhibitor type 1 (PAI-1) are rare disorders of fibrinolysis. Current laboratory assays for analysis of activity of plasminogen and PAI-1 do not provide an accurate correlation with clinical phenotype.

METHODS

The Nijmegen Hemostasis Assay (NHA) was used to simultaneously measure thrombin and plasmin generation in 5 patients with plasminogen deficiency (PLGD) and 10 patients with complete PAI-1 deficiency. Parameters analysed included: lag time ratio, thrombin peak time ratio, thrombin peak height, thrombin potential (AUC), fibrin lysis time, plasmin peak height and plasmin potential. Parameters were expressed as a percentage compared to a reference value of 53 healthy normal controls.

RESULTS

Patients with PLGD demonstrated a short lag time and thrombin peak time, with normal thrombin peak height but an increased AUC. Plasmin generation was able to be detected in only one (23% plasminogen activity) of the five PLGD patients. All ten PAI-1 deficient patients demonstrated a short lag and thrombin peak time, low thrombin peak height with normal AUC. Plasmin generation revealed an increased plasmin peak and plasmin potential; interestingly, there was a large variation between individual patients despite all patients having the same homozygous defect.

CONCLUSION

Patients with either PLGD or PAI-1 deficiency show distinct abnormalities in plasmin and thrombin generation in the NHA. The differences observed in the propagation phase of thrombin generation may be explained by plasmin generation. These results suggest that disorders of fibrinolysis also influence coagulation and a global assay measuring both activities may better correlate with clinical outcome.

Iron handling by the human kidney: glomerular filtration and tubular reabsorption both contribute to urinary iron excretion

In physiological conditions, circulating iron can be filtered by the glomerulus and is almost completely reabsorbed by the tubular epithelium to prevent urinary iron wasting. Increased urinary iron concentrations have been associated with renal injury. However, it is not clear whether increased urinary iron concentrations in patients are the result of increased glomerular iron filtration and/or insufficient tubular iron reabsorption and if these processes contribute to renal injury. We measured plasma and urine iron parameters and urinary tubular injury markers in healthy human subjects ( n = 20), patients with systemic iron overload ( n = 20), and patients with renal tubular dysfunction ( n = 18). Urinary iron excretion parameters were increased in both patients with systemic iron overload and tubular dysfunction, whereas plasma iron parameters were only increased in patients with systemic iron overload. In patients with systemic iron overload, increased urinary iron levels were associated with elevated circulating iron, as indicated by transferrin saturation (TSAT), and increased body iron, as suggested by plasma ferritin concentrations. In patients with tubular dysfunction, enhanced urinary iron and transferrin excretion were associated with distal tubular injury as indicated by increased urinary glutathione S-transferase pi 1-1 (GSTP1-1) excretion. In systemic iron overload, elevated urinary iron and transferrin levels were associated with increased injury to proximal tubules, indicated by increased urinary kidney injury marker 1 (KIM-1) excretion. Our explorative study demonstrates that both glomerular filtration of elevated plasma iron levels and insufficient tubular iron reabsorption could increase urinary iron excretion and cause renal injury.

Whole exome sequencing in the diagnostic workup of patients with a bleeding diathesis

INTRODUCTION

Bleeding assessment tools and laboratory phenotyping often remain inconclusive in patients with a haemorrhagic diathesis.

AIM

To describe the phenotype and genetic profile of patients with a bleeding tendency.

METHODS

Whole exome sequencing (WES) was incorporated in the routine diagnostic pathway of patients with thrombocytopenia (n = 17), platelet function disorders (n = 19) and an unexplained bleeding tendency (n = 51). The analysis of a panel of 126 OMIM (Online Mendelian Inheritance in Man) genes involved in thrombosis and haemostasis was conducted, and if negative, further exome-wide analysis was performed if informed consent given.

RESULTS

Eighteen variants were detected in 15 patients from a total of 87 patients (17%). Causative variants were observed in MYH9 (two cases), SLFN14, P2RY12 and GP9. In addition, one case was considered solved due to combined carriership of F7 and F13A1 variants and one with combined carriership of F2, F8 and VWF, all variants related to secondary haemostasis protein aberrations. Two variants of uncertain significance (VUS) were found in two primary haemostasis genes: GFI1B and VWF. Eight patients were carriers of autosomal recessive disorders. Exome-wide analysis was performed in 54 cases and identified three variants in candidate genes.

CONCLUSION

Based on our findings, we conclude that performing WES at the end of the diagnostic trajectory can be of additive value to explain the complete bleeding phenotype in patients without a definite diagnosis after conventional laboratory tests. Discovery of combinations of (novel) genes that predispose to bleeding will increase the diagnostic yield in patients with an unexplained bleeding diathesis.

Hemorrhagic disorders of fibrinolysis: a clinical review

Hyperfibrinolytic bleeding can be caused by a deficiency of one of the inhibitors of fibrinolysis (plasminogen activator inhibitor type 1 [PAI-1] or α2-antiplasmin [α2-AP]), or an excess of one of the activators of fibrinolysis: tissue-type plasminogen activator or urokinase-type plasminogen activator. This review focuses on the clinical implications of these disorders. The bleeding phenotype of fibrinolytic disorders is characterized by delayed bleeding after trauma, surgery and dental procedures. Bleeding in areas of high fibrinolytic activity is also common, such as menorrhagia and epistaxis. Patients with α2-AP deficiency present with the most severe bleeding episodes. Recently, it was discovered that hyperfibrinolytic disorders are associated with a high rate of obstetric complications such as miscarriage and preterm birth, especially in PAI-1 deficient patients. Hyperfibrinolytic disorders are probably underdiagnosed because of lack of knowledge and lack of accurate diagnostic tests. A substantial part of the large group of patients diagnosed as 'bleeding of unknown origin' could actually have a hyperfibrinolytic disorder. In the case of a high index of suspicion (i.e. because of a positive family history, recurrent bleeding or uncommon type of bleeding such as an intramedullary hematoma), further testing should not be withheld because of normal results of standard hemostatic screening assays. Timely diagnosis is important because these disorders can generally be treated well with antifibrinolytic agents.

Recurrent extramedullary plasmacytoma in asymptomatic multiple myeloma: a case report

Introduction

The gross majority of extramedullary plasmacytomas arise in the lymphatic tissue of the upper respiratory tract. On average, one third of patients with a solid plasmacytoma will develop multiple myeloma, resulting in a worse clinical outcome. We describe a case of rapid recurrent extramedullary plasmacytomas in the background of an asymptomatic multiple myeloma.

Case presentation

A 71-year-old, white Caucasian woman presented with three extramedullary plasmacytomas occurring within a short time period. The third plasmacytoma was accompanied by progressive cervical pain and swallow dysfunction. Additional immunostaining test results were negative for CD56 and showed high MIB-1 expression in the extramedullary plasmacytoma and low MIB-1 expression in the bone marrow. A conventional swallow X-ray did not show any obstruction, however a magnetic resonance imaging scan of her cervical backbone revealed an extramedullary plasmacytoma, threatening her spinal cord. A short course of radiation therapy alleviated her pain and during almost a two-year follow-up period, the multiple myeloma remained asymptomatic, despite the rise in immunoglobulin A lambda levels. After the appearance of the third plasmacytoma, systemic chemotherapy was started to prevent the development of a fourth plasmacytoma, despite the asymptomatic character of the multiple myeloma.

Conclusions

In this case report we describe the rapid appearance of extramedullary plasmacytomas in the background of an asymptomatic multiple myeloma. An immunohistochemical analysis was negative for CD56 and showed high MIB-1 expression in the extramedullary plasmacytoma and low MIB-1 expression in the bone marrow, contributing to the potential underlying pathophysiology of the recurrent extramedullary plasmacytomas and their genetic changes. Systemic chemotherapy was started and no fourth extramedullary plasmacytoma has developed since.

Electronic supplementary material

The online version of this article (doi:10.1186/s13256-014-0506-3) contains supplementary material, which is available to authorized users.

Perioperative dilutional coagulopathy treated with fresh frozen plasma and fibrinogen concentrate: a prospective randomized intervention trial

BACKGROUND AND OBJECTIVES

  Treatment of dilutional coagulopathy by transfusing fresh frozen plasma (FFP) remains sub-optimal. We hypothesized that partial replacement of transfused FFP by fibrinogen concentrate results in improved coagulant activity and haemostasis. This was tested in a controlled clinical intervention trial with patients experiencing massive bleeding during major surgery.

METHODS

  Patients undergoing major elective surgery were treated according to current protocols. When transfusion with FFP was required, patients were randomized as follows: group A received 4 units FFP and group B received 2 units FFP plus 2 g fibrinogen concentrate. Blood samples were taken before and after the intervention. Analysts were blinded to the treatment type.

RESULTS

  Group A (B) consisted of 21 (22) patients, in 16 (17) of whom bleeding stopped after intervention. Plasma fibrinogen increased significantly more in group B (0·57 g/l) than in group A (0·05 g/l). However, levels of prothrombin and factors VIII, IX and X increased more in group A than in group B. Rotational thromboelastometry (ROTEM) of whole blood and plasma revealed improved fibrin clot formation in group B but not in group A. Thrombin generation [calibrated automated thrombogram (CAT)] in plasma increased more in group A. Principal parameters determining whole-blood thromboelastometry were the fibrinogen level and platelet count. In vitro addition of fibrinogen and prothrombin complex concentrate to pre-intervention samples restored both ROTEM and CAT parameters.

CONCLUSIONS

  Partial replacement of transfused FFP by fibrinogen increases fibrin clot formation at the expense of less improved thrombin generation. Coagulation factors other than fibrinogen alone are required for full restoration of haemostasis.

Spatial distribution of factor Xa, thrombin, and fibrin(ogen) on thrombi at venous shear

BACKGROUND

The generation of thrombin is a critical process in the formation of venous thrombi. In isolated plasma under static conditions, phosphatidylserine (PS)-exposing platelets support coagulation factor activation and thrombin generation; however, their role in supporting coagulation factor binding under shear conditions remains unclear. We sought to determine where activated factor X (FXa), (pro)thrombin, and fibrin(ogen) are localized in thrombi formed under venous shear.

METHODOLOGY/PRINCIPAL FINDINGS

Fluorescence microscopy was used to study the accumulation of platelets, FXa, (pro)thrombin, and fibrin(ogen) in thrombi formed in vitro and in vivo. Co-perfusion of human blood with tissue factor resulted in formation of visible fibrin at low, but not at high shear rate. At low shear, platelets demonstrated increased Ca(2+) signaling and PS exposure, and supported binding of FXa and prothrombin. However, once cleaved, (pro)thrombin was observed on fibrin fibers, covering the whole thrombus. In vivo, wild-type mice were injected with fluorescently labeled coagulation factors and venous thrombus formation was monitored in mesenteric veins treated with FeCl(3). Thrombi formed in vivo consisted of platelet aggregates, focal spots of platelets binding FXa, and large areas binding (pro)thrombin and fibrin(ogen).

CONCLUSIONS/SIGNIFICANCE

FXa bound in a punctate manner to thrombi under shear, while thrombin and fibrin(ogen) distributed ubiquitously over platelet-fibrin thrombi. During thrombus formation under venous shear, thrombin may relocate from focal sites of formation (on FXa-binding platelets) to dispersed sites of action (on fibrin fibers).

Impaired thrombin generation and fibrin clot formation in patients with dilutional coagulopathy during major surgery

Patients subjected to haemodilution during surgery are at increased risk of bleeding. We hypothesised that, in the acquired dilutional coagulopathy, insufficient haemostasis is due to either insufficient thrombin generation or insufficient fibrin clot formation. In tissue factor-activated plasmas from patients with coagulation deficiency, we measured time curves of thrombin generation and fibrin clot formation (thromboelastography). Investigated were in study A: 10 patients treated with vitamin K antagonist and five healthy subjects; in study B: 30 patients undergoing cardiopulmonary bypass (CPB) surgery and infused with on average 2,000 ml crystalloids and colloids (no major bleeding); in study C: 58 patients undergoing major general surgery, and transfused with >5,000 ml crystalloids, colloids and red cell concentrates, who experienced major bleeding and were post-transfused with fresh frozen plasma. The treatment with vitamin K antagonist led to a progressive reduction in thrombin generation but not fibrin clot formation. In CPB patients, plasma factor levels post-surgery were 53-60% of normal. This was accompanied by moderate reduction in both haemostatic processes. In plasmas from patients undergoing major surgery, factor levels were 38-41% of normal, and these levels increased after plasma transfusion. Taking preset thresholds for normal thrombin generation and fibrin clot formation, at least one of these processes was low in 88-93% of the patients with (persistent) bleeding, but only in 40-53% of the patients without bleeding. In conclusion, the ability of thrombin generation and fibrin clot formation is independently reduced in acquired dilutional coagulopathy, while minimal levels of both are required for adequate haemostasis.

Effects of plasma dilution on tissue-factor-induced thrombin generation and thromboelastography: partly compensating role of platelets

BACKGROUND

Bleeding upon major surgery or severe trauma is treated by transfusion with crystalloids, colloids, or plasma. This treatment, however, can lead to dilutional coagulopathy and impaired hemostasis. We investigated the suitability of two integrative coagulation tests to measure the hemostatic activity of diluted plasma.

STUDY DESIGN AND METHODS

Plasma from healthy donors was diluted in vitro with saline or colloid (venofundin or gelofusin). Coagulant activity in response to tissue factor was monitored by calibrated automated thrombin (CAT) generation and rotational thromboelastography (TEG), detecting formation of elastic fibrin clots. Plasma from patients receiving fluid infusion during coronary artery bypass grafting (CABG) was analyzed with the same assays.

RESULTS

Optimal activity of CAT and TEG assays required the presence of 10 pmol per L tissue factor and 4 micromol per L phospholipid vesicles or 100 x 10(9) platelets (PLTs) per L. Strikingly, thrombin generation and clot formation became impaired at a higher extent of dilution with PLTs present (< or =40% plasma) than with phospholipid vesicles present (< or =60% plasma). Colloids aggravated the dilution effect on clot formation, but FFP antagonized the dilution effect on thrombin and clot formation. In contrast, fibrinogen and Factor (F)XIII only restored the impaired clot formation. In plasma samples from patients undergoing CABG, CAT and TEG assay variables were altered to an extent corresponding with the volume of fluid infusion.

CONCLUSION

Thrombin generation and clot formation are reduced at a plasma dilution of more than 40 percent. In either process, PLTs can partly compensate for the dilution effect. In vitro dilution with colloids impaired fibrin clot elasticity compared to saline.