Vaccinations are not associated with inhibitor development in boys with severe haemophilia A.

BACKGROUND: Inhibitor development in previously untreated patients (PUPs) with severe haemophilia A is a multifactorial event. It is unknown whether paediatric vaccinations given in close proximity to factor VIII (FVIII) are associated with inhibitor development. OBJECTIVE: To assess whether paediatric vaccinations in close proximity to FVIII within the first 75 exposure days (EDs) are associated with inhibitor development in PUPs with severe haemophilia A. METHODS: We included 375 PUPs with severe haemophilia A (<0.01 IU/mL) from the PedNet Registry who had received vaccinations between the first and 75th ED or inhibitor development. Inhibitor risk was compared between patients who did and who did not receive vaccinations within 24, 72 or 120 hours of FVIII infusion. Unadjusted and adjusted hazard ratios were calculated for any or repeated vaccinations in close proximity to FVIII, using Cox regression. RESULTS: Inhibitor development occurred in 77 of 375 patients (20.5%). Overall inhibitor development appeared similar or lower in patients receiving vaccinations in close proximity to FVIII as compared to patients receiving vaccinations without FVIII: for 24 hours, this was 19.2% and 21.4% (P = .186), for 72 hours, 16.4% and 27.3% (P = .023) and for 120 hours, 18.3% and 25.0% (P = .085), respectively. CONCLUSION: We found no association between vaccinations given in close proximity to FVIII exposure within the first 75 EDs and inhibitor development. Our data do not support avoiding administration of FVIII at time of routine vaccinations.

Continuous infusion of recombinant factor VIII formulated with sucrose in surgery: non-interventional, observational study in patients with severe haemophilia A.

In haemophilia A, continuous infusion (CI) of FVIII perioperatively provides a more constant FVIII level than conventional bolus injections, avoiding low trough levels that could increase bleeding risk. Due to the low number of surgical cases in clinical trials, especially in haemophilia, more information on the clinical practice of CI from observational studies is helpful. We aimed to evaluate the effectiveness and safety of CI with recombinant factor VIII formulated with sucrose (rFVIII-FS) in a typical surgery practice setting. This was a non-interventional study in 12 centres. Patients with severe haemophilia A who received rFVIII-FS by CI during and after surgery were included in this study if they had more than 150 exposure days (EDs) to any FVIII product and had no history of inhibitors before CI. Patients were observed during the entire course of CI, with monitoring up to 3 months thereafter. Twenty-five patients with 28 surgeries were included in the analysis. Median age was 51.7 (range 10-75). Most (75%; 21/25) patients underwent orthopaedic surgeries. The median dose of rFVIII-FS consumed during CI was 376 IU kg(-1) (range 157.9-3605.6 IU kg(-1)) with a greater median dose for orthopaedic surgeries (424.0 IU kg(-1)) compared to non-orthopaedic surgeries (278.5 IU kg(-1)). 95% of all FVIII measurements (214/224) were on target. Efficacy and tolerability were rated as good/excellent in 89.3% (25/28) of surgeries. No inhibitors were observed during or after surgery. This study demonstrates the effectiveness of CI with rFVIII-FS during surgery in patients with severe haemophilia A in a clinical practice setting.

Prospective observational cohort studies for studying rare diseases: the European PedNet Haemophilia Registry.

Haemophilia is a rare disease. To improve knowledge, prospective studies of large numbers of subjects are needed. To establish a large well-documented birth cohort of patients with haemophilia enabling studies on early presentation, side effects and outcome of treatment. Twenty-one haemophilia treatment centres have been collecting data on all children with haemophilia with FVIII/IX levels up to 25% born from 2000 onwards. Another eight centres collected data on severe haemophilia A only. At baseline, details on delivery and diagnosis, gene mutation, family history of haemophilia and inhibitors are collected. For the first 75 exposure days, date, reason, dose and product are recorded for each infusion. Clinically relevant inhibitors are defined as follows: at least two positive inhibitor titres and a FVIII/IX recovery <66% of expected. For inhibitor patients, results of all inhibitor- and recovery tests are collected. For continued treatment, data on bleeding, surgery, prophylaxis and clotting factor consumption are collected annually. Data are downloaded for analysis annually. In May 2013, a total of 1094 patients were included: 701 with severe, 146 with moderate and 247 with mild haemophilia. Gene defect data were available for 87.6% of patients with severe haemophilia A. The first analysis, performed in May 2011, lead to two landmark publications. The outcome of this large collaborative research confirms its value for the improvement of haemophilia care. High-quality prospective observational cohorts form an ideal source to study natural history and treatment in rare diseases such as haemophilia.

Impact of HLA alleles and cytokine polymorphisms on inhibitors development in children with severe haemophilia A.

Human Leucocyte Antigen (HLA) alleles, cytokine polymorphisms and the type of factor VIII (FVIII) gene mutation are among predisposing factors for inhibitors (inh) development in children with severe haemophilia A (HA). The aim was to investigate the correlations among (i) FVIII gene intron-22 inversion, (ii) HLA alleles and haplotypes and (iii) certain cytokine polymorphisms, with the risk for FVIII inhibitors development in 52 Greek severe HA children, exclusively treated with recombinant concentrates. We performed Long-Range PCR for detection of intron-22 inversion and PCR-SSP, PCR-SSO for genotyping of HLA-A, B, C, DRB1, DQB1 alleles and also for cytokine polymorphisms of TNF-α, TGF-ß1, IL-10, IL-6 and IFN-γ. Chi-squared test and Fischer's exact test were used for statistical analysis. A total of 28 children had developed inhibitors (Group I), 71.4% high responding, while 24 had not (Group II). No statistically increased intron-22 inversion prevalence was found in Group I compared with Group II (P = 0.5). Comparison of HLA allele frequencies between the two groups showed statistically significant differences in the following genotypes (i) promoting inhibitors development: DRB1*01(P = 0.014), DRB1*01:01(P = 0.011) and DQB1*05:01 (P = 0.005) and (ii) possibly protecting from inhibitors development: DRB1*11 (P = 0.011), DRB1*11:01 (P = 0.031), DQB1*03 (P = 0.004) and DQB1*03:01 (P = 0.014). Analysis of cytokines revealed a higher incidence of inhibitor detection only in homozygotes of the haplotypes ACC and ATA for IL-10 polymorphisms (P = 0.05). There is evidence that HLA alleles and cytokine polymorphisms play an important role in FVIII inh development. On the contrary, no statistically significant results were obtained for intron-22 inversion and its impact on FVIII inhibitors formation.

Coagulation factor activity and clinical bleeding severity in rare bleeding disorders: results from the European Network of Rare Bleeding Disorders.

BACKGROUND: The European Network of Rare Bleeding Disorders (EN-RBD) was established to bridge the gap between knowledge and practise in the care of patients with RBDs. OBJECTIVES: To explore the relationship between coagulation factor activity level and bleeding severity in patients with RBDs. PATIENTS/METHODS: Cross-sectional study using data from 489 patients registered in the EN-RBD. Coagulation factor activity levels were retrieved. Clinical bleeding episodes were classified into four categories according to severity. RESULTS: The mean age of patients at data collection was 31 years (range, 7 months to 95 years), with an equal sex distribution. On linear regression analysis, there was a strong association between coagulation factor activity level and clinical bleeding severity for fibrinogen, factor (F) X, FXIII, and combined FV and FVIII deficiencies. A weaker association was present for FV and FVII deficiencies. There was no association between coagulation factor activity level and clinical bleeding severity for FXI. The coagulation factor activity levels that were necessary for patients to remain asymptomatic were: fibrinogen, > 100 mg dL(-1); FV, 12 U dL(-1); combined FV + VIII, 43 U dL(-1); FVII, 25 U dL(-1); FX, 56 U dL(-1) ; FXI, 26 U dL(-1); FXIII, 31 U dL(-1). Moreover, coagulation factor activity levels that corresponded with Grade III bleeding were: undetectable levels for fibrinogen, FV and FXIII, < 15 U dL(-1) for combined FV + VIII; < 8 U dL(-1) for FVI; < 10 U dL(-1) for FX; and < 25 U dL(-1) for FXI. CONCLUSIONS: There is a heterogeneous association between coagulation factor activity level and clinical bleeding severity in different RBDs. A strong association is only observed in fibrinogen, FX and FXIII deficiencies.

Assessment of the progression of haemophilic arthropathy in children.

Arthropathy is considered as an irreversible and progressive complication in patients with haemophilia, even in children on prophylaxis. To estimate the progression of haemophilic arthropathy, 85 joints of 24 boys with severe (n = 18) and moderate (n = 6) haemophilia (A: 22, B: 2) were investigated with clinical examination, X-rays and magnetic resonance imaging (MRI) at two time periods (time 0 and 1). Patients' age at time 0 was 10.5 +/- 3.6 years and time elapsed to time 1 was 3.8 +/- 1.4 years. At time 0: all investigated joints had more than three bleeds. Sixteen boys were on secondary prophylaxis for 5.4 +/- 2.8 years. Clinical score (a modification of World Federation of Haemophilia's scale): 2.0 +/- 3.6, X-ray score (Pettersson): 2.1 +/- 2.8, MRI score (Denver): 4.5 +/- 3.8. After the first evaluation, prophylaxis was intensified in 11 children and initiated in four. At time 1: clinical score: 1.5 +/- 3.1, X-ray: 1.7 +/- 2.7, MRI score: 5.1 +/- 4.1. On average, the clinical and X-ray scores showed a significant improvement (26% and 40% of the joints respectively, P < 0.01) and the number of haemarthroses evidenced a threefold reduction from time 0 to 1 (P < 0.01), findings that could be associated with the modification of prophylaxis after time 0. MRI findings showed deterioration in 34% of the joints. Conversely, 14 joints (16.5%) with mild or moderate synovitis without cartilage degradation at time 0 showed an improvement at time 1. The information carried by the three scales could be divided into information shared by the three scores and information specific to each score, thus giving a more complete picture of joint damage caused by bleedings.

Comparative study of validity of clinical, X-ray and magnetic resonance imaging scores in evaluation and management of haemophilic arthropathy in children.

To evaluate joints alterations, we performed clinical examination, X-rays and magnetic resonance imaging (MRI) (Denver score) in 165 joints of 40 children with severe (n, 32) or moderate (n, 8) haemophilia A or B. All investigated joints had a history of more than three bleeds. At evaluation, 25 of 40 haemophilic patients were on prophylaxis for the last 1-8 years (mean: 3.5 years). MRI revealed chronic synovitis in 55.4% and 50% of joints, which were diagnosed, as normal by the clinical scale and plain radiography respectively. Moreover, MRI unmasked more profound alterations than those observed by plain radiography in 70% of cases. Statistical analysis showed that the clinical and Pettersson scores in contrast to the Denver score provide an underestimation of arthritic changes. Besides, Denver score did not provide resolution in differentiating stages of arthropathy, because of its inherent nature; however, a score of 6 expressing severe synovitis seemed to be the cut-off value for the distinction of severe cases. Based on MRI findings we intensified prophylaxis in nine children and initiated it in another nine children. Five children, who were already on prophylaxis complied with our recommendations and eliminated haemorrhages. Finally, three boys with severe haemophilic arthropathy in knees underwent successful chemical synovectomy with rifampicin.

Mutations and polymorphisms in genes affecting hemostasis proteins and homocysteine metabolism in children with arterial ischemic stroke.

BACKGROUND: The pathogenesis of thrombosis in childhood seems to be multifactorial implicating genetic and environmental factors. AIM: To compare the distributions of mutations/polymorphisms in genes affecting hemostasis (factor V Leiden - FVL, FV H1298R-FVR2, FII 20210A, b-Fib 455G>A, FXIII V34L, PAI-1 4G, HPA-1b) or homocysteine metabolism (MTHFR C677T, MTHFR A1298C) among 90 children with arterial ischemic stroke (AIS) and 103 controls, and to associate the carriage of these mutations/polymorphisms with their corresponding proteins in children with AIS. RESULTS: AIS was more frequent in boys (p < 0.01). No studied mutation/polymorphism was found to be a risk factor for AIS, except for FVL [odds ratio 4.2 (95% CI 1.5-12.1)], the presence of which was even higher in 31 children with congenital AIS [odds ratio 6.82 (95% CI 2.0-22.8)]. FVL carriers had an odds ratio of 5.76 (95% CI 1.6-6.4) when FVR2 was absent. In thrombosed children, activated protein C resistance, prothrombin and fibrinogen levels were higher in the presence of FVL, FII20210A or b-Fib 455G-->A, respectively. Double heterozygotes in both MTHFR C677T and A1298T or homozygotes in one had significantly elevated homocysteine levels. CONCLUSION: Except for FVL, no definite conclusion could be reached regarding the involvement of the studied mutations/polymorphisms in childhood AIS.

Rituximab in the treatment of high responding inhibitors in severe haemophilia A.

The development of antibodies to factor VIII (FVIII) in severely affected haemophilia A patients is a serious complication associated with increased morbidity and mortality. Bypassing agents are used to treat acute bleeding episodes; however, elimination of the inhibitors can only be achieved with immune tolerance therapy (ITT) in 60-80% of cases. High responding (HR) inhibitors are more likely to respond to ITT if the titre is decreased to <5 BU over time or in selected cases after the administration of immunosuppressive drugs, plasmapheresis or immunoabsorption, techniques difficult to apply in children. Anti-CD20 (rituximab), a monoclonal antibody, was given as an alternative treatment in two haemophilic children with HR inhibitors and impaired quality of life, due to recurrent haemarthrosis. Rituximab was given at the dose of 375 mg m(-2), once weekly for four consecutive weeks. Both patients showed a partial response to rituximab reducing the inhibitor titre to <5 BU, thus facilitating ITT initiation; however, only the older patient eradicated the inhibitor within 21 days after application of ITT. The second patient, despite depletion of B cells, did not respond to ITT. No long-term side effects have been observed in both patients for a follow-up period of 20 and 18 months respectively. In conclusion, rituximab appears to be an alternative effective therapy to rapidly reduce or eliminate the inhibitor in selected cases of severely affected haemophiliacs before further proceeding to ITT. However, the dose and appropriate schedule, as well as long-term side effects need further investigation.

Mutations and polymorphisms in genes affecting haemostasis components in children with thromboembolic events.

The distribution of mutations/polymorphisms in genes affecting haemostasis [factor V Leiden (FVL), FV H1298R (FVR(2)), FII 20210A, b-Fib 455G-->A, FXIII V34L, PAI-1 4G, HPA-1b] among 141 children with thrombosis at various sites and 103 controls was compared. Additionally, the carriage of these mutations/polymorphisms was associated with the levels of their corresponding proteins in thrombosed children. Thrombosis was more frequent in boys (p = 0.021). No studied mutation/polymorphism was found to be a risk factor for thrombosis, except for FVL (odds ratio 3.8, 95% CI 1.4-10.6). The risk of thrombosis for FVL carriers was twice as high in children with an idiopathic thrombosis (odds ratio 5.4) than in thrombosed children with an underlying disease or a triggering event (odds ratio 2.7). FVL carriers had an odds ratio of 5.9 (95% CI 1.8-19.6) when FVR(2) was absent. In thrombosed children, the activated protein C resistance ratio was significantly lower in the presence of FVL (p < 0.001). Prothrombin and fibrinogen levels, although higher in FII 20210A and b-Fib 455G-->A carriers, did not reach statistical significance.

Retrospective evaluation of long-term efficacy and safety of splenectomy in chronic idiopathic thrombocytopenic purpura in children.

AIM: To review the long-term efficacy and safety of splenectomy in children with chronic idiopathic thrombocytopenic purpura (cITP). PATIENTS AND METHODS: Data from 33 splenectomized children were retrospectively analysed (median follow up period: 18.8 y from the removal of the spleen). The median age of children at splenectomy was 12 y and the median ITP duration 3.3 y. Indications for splenectomy were: persistent severe thrombocytopenia with extensive purpura, epistaxis and/or gum bleeds, menorrhagia (n = 5) and severe or recurrent haemorrhage from various sites (n = 11). RESULTS: Eighty-five per cent of the patients showed an excellent (n = 26) or partial response to splenectomy. Five children (15%), all females, failed to respond. Of the responders, 25% experienced a transient recurrence of thrombocytopenia within 6 mo to 4 y from splenectomy. The mortality rate due to severe sepsis was 3%. However, the majority of the splenectomized patients have not so far suffered any severe or mild bacterial infection, despite incomplete vaccination and/or antibiotic prophylaxis. CONCLUSION: Splenectomy remains the only effective therapeutic modality for children with cITP, although it is associated with transient recurrence and rarely with post-splenectomy sepsis, which could be fatal. Nonetheless, splenectomy should be the last treatment option for the cITP patient, after all available therapeutic modalities have been exhausted and the child still remains profoundly thrombocytopenic and symptomatic.

Prothrombotic factors in neonates with cerebral thrombosis and intraventricular hemorrhage.

AIM: To investigate whether the factor V Leiden mutation (FVL), the prothrombin gene G20210A variant or the methylenetetrahydrofolate reductase (MTHFR) C677T genotype are risk factors for central nervous system (CNS) thrombosis or intraventricular hemorrhage (IVH) in neonates. METHODS: Thirteen full-term infants with cerebral infarct documented with magnetic resonance imaging were assessed with the whole spectrum of assays for thrombophilia including the three DNA-based prothrombotic factors. The frequency of congenital defects was compared with that observed in 38 healthy full-term infants. The genetic defects were also assessed in 55 premature neonates, gestational age <32 wk, 17 of whom developed IVH, grade II-IV. The remaining 38 premature neonates without IVH were used as controls. RESULTS: In the CNS thrombosis group: a prothrombotic factor was detected in 53% of patients and an underlying disease or a triggering event in 61.5%. The frequency of FVL in thrombosed neonates was higher (23%) than in the group of healthy full-term infants (10.5%), although it did not reach statistical significance. IVH developed in 30.9% of premature neonates. Apart from several maternal or neonatal risk factors for IVH, FII G20210A was found in a considerably higher prevalence in the cohort of neonates with IVH (12%) than in those without (2%), although the difference was not statistically significant. CONCLUSION: The pathogenesis of cerebral thrombosis or IVH in neonates is multifactorial. Along with underlying diseases or triggering events, congenital prothrombotic factors (FVL or FII G20210A) showed a trend towards a higher frequency in full-term infants with CNS thrombosis or premature neonates with IVH than in controls. However, their contribution to neonatal cerebral thrombosis or IVH remains to be determined.

Indications of coagulation and/or fibrinolytic system activation in healthy and sick very-low-birth-weight neonates.

A combined hemostatic defect consisting of a reduction in certain procoagulants, anticoagulants (antithrombin III-ATIII-, protein C-PC-) and components of the fibrinolytic system (plasminogen-Plg-) was demonstrated in very-low-birth-weight infants (VLBW <1,500 g) with gestational age 26-32 weeks. Sixteen of them were healthy, 28 were suffering from RDS and 24 from septicemia. The hemostatic defect was more profound in the RDS group, nevertheless increased TAT (thrombin + ATIII complex) and/or PAP values (plasmin + a2-antiplasmin complex) was a more frequent finding in the septicemic group of infants (91.8 vs. 17.9%). Moderate-to-severe thrombocytopenia was detected in a higher percentage in the septicemic (70.8%) than in the RDS group (50%), and increased D-dimers were demonstrated in 34.8 and 28.6% of the infants, respectively. Elevated TAT or PAP values were not always associated with gross coagulation abnormalities, and advanced disseminated intravascular coagulation (DIC) was only documented in 16.7% of the septicemic and 7.1% of the RDS infants. None of the VLBW neonates presented with clinical evidence of thrombosis, although hemorrhagic manifestations were apparent in 34.8 and 14.3% of the neonates with septicemia or RDS, respectively, mainly due to DIC or severe thrombocytopenia. In conclusion, increased TAT and/or PAP values are good indicators of the in vivo activation of the hemostatic system, but still their impact on sick neonates morbidity and mortality remains unknown.

Diffuse splenic and visceral hemangiomas complicated by chronic consumption coagulopathy.

The case of a 7-year-old girl with a 2 year history of easy bruising associated with thrombocytopenia is reported. On admission she presented with ecchymoses, abdominal distention and splenomegaly. Hemostasis investigation revealed a consumption coagulopathy. Several radiological studies failed to confirm the diagnosis of diffuse splenic and visceral hemangiomatosis, which was eventually established by an explorative laparotomy. Platelet count and the other coagulation abnormalities progressively returned to normal after splenectomy, although the remaining hemangiomas were extensive.

Haemostatic variables in phenylketonuric children under dietary treatment.

Classical phenylketonuria (PKU) (McKusick 261600) is an inborn error of metabolism treated by a controlled low-phenylalanine (Phe) diet started as soon as possible in the first days of life. Such a diet can be achieved with vegetable protein and can be considered non-atherogenic because of the reduction of animal products. Thirty patients with PKU were classified into two groups according to their annual mean Phe levels. Their daily protein intake was largely replaced by PKU2 Milupa which contains a mixture of amino acids. The product has no phenylalanine or fat of any kind. Thirty-eight (38) individuals of comparable age were used as controls. Group A (n = 15) had good compliance with the special diet (Phe mean 192 +/- 115 mumol/L); group B (n = 15) did not strictly adhere to the diet (Phe mean 595 +/- 263 mumol/L). Certain haemostatic components (factors I, VII, VIII, and X, antithrombin III, protein C, and plasminogen) and lipid variables (cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, very-low-density lipoprotein) as well as Phe levels were estimated. All the haemostatic factors studied were found within the normal range with the exception of a significant reduction in protein C in both groups of PKU patients. Furthermore, a statistically significant reduction in factor VII and X concentrations was observed in patients on strict diet. Cholesterol and low-density lipoprotein concentrations were significantly lower in PKU children compared to normal controls. It is suggested that even though the special diet of PKU children, especially in group A, is rich in vegetables, the reduced fat intake might have impaired the absorption of vitamin K and its delivery to the site of synthesis of vitamin K-dependent haemostatic factors.