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The incidence of factor IX (FIX) inhibitors in severe hemophilia B (SHB) is not well defined. Frequencies of 3-5% have been reported but most studies to date have been small, including patients with different severities, and without prospective follow up for inhibitor incidence. The study objective was to investigate the inhibitor incidence in patients with SHB followed up for to 500 exposure days (ED), the frequency of allergic reactions, and the relationship with genotypes. Consecutive previously untreated patients (PUP) with SHB enrolled into the PedNet cohort were included. Detailed data was collected for the first 50 ED, followed by the annual collection of the inhibitor status and allergic re-actions. The presence of inhibitors was defined by at least two consecutive positive samples. Additionally, data on FIX gene mutation was collected. One hundred and fifty-four PUP with SHB were included; 75% were followed up until 75 ED, and 43% until 500 ED. Inhibitors developed in 14 patients (seven high-titer). The median number of ED at inhibitor manifestation was 11 (interquartile range [IQR]: 6.5-36.5). The cumulative inhibitor incidence was 9.3% (95% Confidence Interval [CI]: 4.4-14.1) at 75 ED, and 10.2% (95% CI: 5.1-15.3) at 500 ED. Allergic reactions occurred in four (28.6%) inhibitor patients. Missense mutations were most frequent (46.8%) overall but not associated with inhibitors. Nonsense mutations and deletions with large structural changes comprised all mutations among inhibitor patients and were associated with an inhibitor risk of 26.9% and 33.3%, respectively. In an unselected, well-defined cohort of PUP with SHB, the cumulative inhibitor incidence was 10.2% at 500 ED. Nonsense mutations and large deletions were strongly associated with the risk of inhibitor development. The ‘PedNet Registry’ is registered at clinicaltrials.gov; identifier: NCT02979119.

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 (

International audience; Objectives: To evaluate the applicability and compliance with guidelines for early initiation of long-term prophylaxis in infants with severe hemophilia A and to identify factors associated with guideline compliance.Study design: This real-world, prospective, multicenter, population-based FranceCoag study included almost all French boys with severe hemophilia A, born between 2000 and 2009 (ie, after guideline implementation).Results: We included 333 boys in the study cohort. The cumulative incidence of long-term prophylaxis use was 61.2% at 3 years of age vs 9.5% in a historical cohort of 39 boys born in 1996 (ie, before guideline implementation). The guidelines were not applicable in 23.1% of patients due to an early intracranial bleeding or inhibitor development. Long-term prophylaxis was delayed in 10.8% of patients. In the multivariate analysis, 2 variables were significantly associated with "timely long-term prophylaxis" as compared with "delayed long-term prophylaxis": hemophilia treating center location in the southern regions of France (OR 23.6, 95% CI 1.9-286.7, P = .013 vs Paris area) and older age at long-term prophylaxis indication (OR 7.2 for each additional year, 95% CI 1.2-43.2, P = .031). Long-term prophylaxis anticipation was observed in 39.0% of patients. Earlier birth year (OR 0.5, 95% CI 0.3-0.8, P = .010 for birth years 2005-2009 vs 2000-2004) and age at first factor replacement (OR 1.9 for each additional year, 95% CI 1.2-3.0, P = .005) were significantly associated with "long-term prophylaxis guideline compliance" vs "long-term prophylaxis anticipation."Conclusions: This study suggests that long-term prophylaxis guidelines are associated with increased long-term prophylaxis use. However, early initiation of long-term prophylaxis remains a challenge.

The optimal mode of delivery for a pregnant hemophilia carrier is still a matter of debate. The aim of the study was to determine the incidence of intracranial hemorrhage and other major bleeds in neonates with moderate and severe hemophilia in relationship to mode of delivery and known family history. A total of 926 neonates, 786 with severe and 140 with moderate hemophilia were included in this PedNet multicenter study. Vaginal delivery was performed in 68.3% (n=633) and Cesarean section in 31.6% (n=293). Twenty intracranial hemorrhages (2.2%) and 44 other major bleeds (4.8%) occurred. Intracranial hemorrhages occurred in 2.4% of neonates following vaginal delivery compared to 1.7% after Cesarean section (P=not significant); other major bleeds occurred in 4.2% born by vaginal delivery and in 5.8% after Cesarean section (P=not significant). Further analysis of subgroups (n=813) identified vaginal delivery with instruments being a significant risk factor for both intracranial hemorrhages and major bleeds (Relative Risk: 4.78-7.39; P

Hemarthroses and muscle bleeds are well-known and well-documented complications in pediatric and young adult hemophilia patients. In contrast, deep bleeds in atypical locations can be a diagnostic challenge, since clinicians and radiologists are often unfamiliar with their clinical and radiological features. Some atypical bleeds, however, can be life-threatening or severely disabling, highlighting the need for prompt, accurate diagnosis. Rare bleeds include central nervous system bleeds (including intracranial and spinal hematomas), urogenital bleeds, intra-abdominal bleeds (mesenteric and gastrointestinal wall hematomas) and pseudo tumors in unusual locations like the sinonasal cavities. Because clinical assessment can be difficult, clinicians and radiologists should be aware of the possibility of these rare complications in their hemophilia patients, so that they can avoid unnecessary invasive diagnostic and surgical procedures and institute prompt, appropriate treatment. The purpose of this review is to illustrate the imaging features of bleeds that occur in rare locations in young (i.e., children and young adults) patients with hemophilia to make the reader more familiar with these conditions.

IntroductionSevere haemophilia is a rare disease characterised by spontaneous bleeding from early childhood, which may lead to various complications, especially in joints. It is nowadays possible to avoid these complications thanks to substitutive therapies for which the issue of adherence is major. The transition from adolescence to adulthood in young people with severe haemophilia is a critical period as it is associated with a high risk of lack of adherence to healthcare, which might have serious consequences on daily activities and on quality of life.Methods and analysisWe present the protocol for a cross-sectional, observational, multicentric study to assess the differences between adolescents and young adults with severe haemophilia in France through the transition process, especially on adherence to healthcare. This study is based on a mixed methods design, with two complementary and consecutive phases, comparing data from a group of adolescents (aged 14–17 years) with those from a group of young adults (aged 20–29 years). The quantitative phase focuses on the determinants (medical, organisational, sociodemographic and social and psychosocial and behavioural factors) of adherence to healthcare (considered as a marker of the success of transition). The qualitative phase explores participants’ views in more depth to explain and refine the results from the quantitative phase. Eligible patients are contacted by the various Haemophilia Treatment Centres participating in the French national registry FranceCoag.Ethics and disseminationThe study was approved by the French Ethics Committee and by the French National Agency for Medicines and Health Products Safety (number: 2016-A01034-47). Study findings will be disseminated to the scientific and medical community in peer-reviewed journals and presented at scientific meetings. Results will be popularised to be communicated via the French association for people with haemophilia to participants and to the general public.Trial registration numberNCT02866526; Pre-results.

International audience

Henoch-Schonlein purpura is a common form of immunological vasculitis in children. Hemophilia A is a genetic disorder, inherited in a X-linked recessive pattern, and characterized by spontaneous hemorrhage or prolonged bleeding due to factor VIII deficiency. The clinical signs depend on the severity of factor VIII deficiency. We herein report the case of a 4-year-old boy admitted to the emergency room for typical rheumatoid purpura, associated with a lengthening of aPTT, whose exploration had uncovered mild hemophilia A. Laboratory assays should explore lengthening of aPTT: firstly the presence of lupus anticoagulant without bleeding risk, in an inflammatory context; secondly a deficiency of VWF and one of the factors involved in the extrinsic coagulation pathway associated with bleeding risk.

Introduction.In patients with hemophilia treated with factor VIII products, the development of inhibitory antibodies poses the largest safety risk. Especially during the first 50 exposure days (EDs), up to 37% of patients with severe hemophilia A have been reported to develop an inhibitor. To study neo-immunogenicity of products and new treatment strategies, patients have been distinguished into previously untreated (PUPs) and previously treated patients (PTPs); the latter defined as patients treated for more than 150 EDs. The number of 150 EDs was established in the eighties during a time when most patients received on-demand treatment and testing for inhibitors was not frequently performed. More recent studies on inhibitor incidence in PUPs with severe hemophilia A report that 50% of inhibitors develop within 14-15 EDs, however the cut-off number of EDs for a PUP to become a PTP is not well defined. The aim of this study was to define the number of EDs for PUPs to become PTPs based on long-term follow-up of patients with severe hemophilia A Methods.All patients with severe hemophilia A born after January 1, 2000, treated for at least 1 ED and followed prospectively until inhibitor development or the number of EDs at last follow-up, were included. The number of EDs at inhibitor development is the last exposure day before the first positive titer was reported. An inhibitor was defined as positive when at least two positive inhibitor titers were measured. Positivity was defined according to the cut-off level in each individual center's laboratory. Results.Of 1,038 PUPs with severe hemophilia A, 930 (89.6%) were followed until 75 EDs, 429 until 500 EDs and 212 until 1000 EDs. In total, 300 inhibitors developed, of which 298 (99.3%) within the first 75 EDs. Thereafter only two inhibitors developed, both low titer: after 249 and 264 EDs. Conclusion.Almost all inhibitors develop during the first 75 EDs. Patients with severe hemophilia A can be defined as PTP after 75 instead of 150 exposure days. A change of definition of PTP will increase the number of severe hemophilia A patients eligible for new therapies. Disclosures Santagostino: Bioverativ: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees; Shire: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Kedrion: Membership on an entity's Board of Directors or advisory committees; Sobi: Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Grifols: Membership on an entity's Board of Directors or advisory committees; Octapharma: Membership on an entity's Board of Directors or advisory committees. Male:SOBI: Speakers Bureau; Shire: Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Octapharma: Speakers Bureau; Novo Nordisk: Speakers Bureau; Biotest: Speakers Bureau; Bayer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; CSL Behring: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Oldenburg:Novo Nordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Octapharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Shire: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biogen Idec: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Chugai: Honoraria, Membership on an entity's Board of Directors or advisory committees; Grifols: Honoraria, Membership on an entity's Board of Directors or advisory committees; Biotest: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; CSL Behring: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Swedish Orphan Biovitrum: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Liesner:Baxalta: Consultancy, Research Funding; Novo Nordisk: Research Funding, Speakers Bureau; Sobi: Speakers Bureau; Bayer: Consultancy, Research Funding; Roche: Research Funding; Octapharma: Consultancy, Other: Clinical study investigator for NuProtect Study (Octapharma sponsored), Research Funding, Speakers Bureau. Carcao:Shire: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Octapharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Grifols: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; CSL-Behring: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; LFB: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bioverativ/Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biotest: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Nolan:CSL Behring: Research Funding; Sobi: Research Funding; Bayer: Research Funding. Álvarez-Roman:Shire: Consultancy; NovoNordisk: Consultancy; SOBI: Consultancy. Koenigs:Gilead: Research Funding; CSL Behring: Consultancy, Research Funding; Pfizer: Research Funding, Speakers Bureau; Bayer: Consultancy, Research Funding, Speakers Bureau; Intersero: Research Funding; Bioverativ: Consultancy; Roche/Chugai: Consultancy; EU (IMI, FP7): Research Funding; Sobi: Consultancy, Research Funding, Speakers Bureau; Shire: Consultancy, Research Funding; Novo Nordisk: Consultancy, Speakers Bureau; Biotest: Research Funding, Speakers Bureau; Jansen: Research Funding.

During the last decades, long-term prophylaxis has become the gold standard for the treatment of children with severe haemophilia A or B. Prophylactic replacement regimens modify the natural history of the disease by aiming at the prevention of haemarthrosis, target joints and arthropathy. This treatment represents a constraint and an enhanced exposure to anti-haemophilic concentrates, which means potential increase of related risks and significant additional cost. The context of crisis of confidence due to the blood borne infections in the 1980s, may have delayed prophylaxis as an universal gold standard.In the early 2000s, the French group CoMETH proposed recommendations based on the review of the international experience. At first, specific guidelines of long-term prophylaxis were dedicated to children with severe haemophilia A or B, aged 3 years or less, with no history of target joint or arthropathy. The main concerns of this regimen consist in the early start and the escalating intensification of the treatment. In the French haemophilia care centres, the diffusion of these guidelines has apparently induced a significant turning point in therapeutic practices for haemophilia children. In 2006, more comprehensive recommendations were diffused to take into account all the children with severe haemophilia, whatever the bleeding history and joint status. The analysis of their impact, jointly with the National cohort "France Coag Network", will first assess the widespread implementation of the recommendations and the observance of the prophylactic regimen and identify factors associated to the compliance.

Prophylaxis for hemophilia is the scheduled infusion of the missing clotting factor with pre-specified dose, with the intention of preventing bleeds and subsequent hemophilic arthropathy. It is the treatment of choice for patients with severe hemophilia A in countries with available resources.[1][1

Henoch-Schönlein purpura is a common form of immunological vasculitis in children. Hemophilia A is a genetic disorder, inherited in a X-linked recessive pattern, and characterized by spontaneous hemorrhage or prolonged bleeding due to factor VIII deficiency. The clinical signs depend on the severity of factor VIII deficiency. We herein report the case of a 4-year-old boy admitted to the emergency room for typical rheumatoid purpura, associated with a lengthening of aPTT, whose exploration had uncovered mild hemophilia A. Laboratory assays should explore lengthening of aPTT: firstly the presence of lupus anticoagulant without bleeding risk, in an inflammatory context; secondly a deficiency of VWF and one of the factors involved in the extrinsic coagulation pathway associated with bleeding risk.

Phenotypic variability is well recognized in severe hemophilia A. A few studies, mainly in adults treated lifelong on demand, suggest that bleeding phenotype correlates with factor VIII gene (F8) mutation type. Because treatment regimens influence outcomes to a large extent, examining bleeding phenotype during the first years of life may be the most suitable way to define this variability. We set out to analyze the very early phenotypic expression of severe hemophilia A in 621 consecutively enrolled, well-characterized previously untreated patients and to correlate this with patients' F8 mutation. Detailed information was collected on bleeds and treatment of the first 75 exposure days or until inhibitor development. F8 mutation type was known for 531 patients; 402 had null mutations and 129 had non-null mutations. Considering only patients who had not started prophylaxis or developed an inhibitor before select bleeding events, we found that patients with null mutations experienced their first bleed and first joint bleed at younger median ages than patients with non-null mutations (9.7 vs 10.9 months and 13.8 vs 16.1 months, respectively). We conclude that F8 mutation type accounts for only a small component of the significant phenotypic variability found among patients with severe hemophilia A.

The development of anti-FVIII antibodies (i.e., inhibitors) is the major side effect of severe hemophilia A treatment. Inhibitors mainly develop in children during the first 50 exposure days and are classified in low-and high-titer (i.e., peak titer < or > 5 UB/ml). High-titer inhibitors have the major clinical impact. At diagnosis however, the real nature of the antibody is not clear in all patients, since some low-titer inhibitors may progress to high-titer. The determinants of the evolution from low- to high-titer inhibitors are still unclear and the aim of the present study was to investigate potential risk factors associated with the progression from low- to high-titer inhibitors. This study is a follow-up study of the PedNet Registry and includes 260 children with severe hemophilia A and clinically relevant inhibitors, born between 1990 and 2009 and consecutively recruited from 31 hemophilia centers in 16 countries. Clinical and laboratory data were collected from the date of first positive inhibitor test and covered a minimum of 3-years follow-up. Factors potentially associated with progression from low- to high-titer inhibitor development were analyzed using univariate and multivariate logistic regression. F8 mutation type was known in 247 patients (95%), including 202 (82%) null mutations (i.e., large deletions, nonsense mutations and inversions). Positive family history of inhibitors was present in 37 of 99 (37%) with positive family history of hemophilia. At diagnosis 49% (n=127) had low-titer inhibitors, however, upon FVIII re-exposure, 50% of low-titer inhibitors progressed to high-titer and only 25% of patients (n=69) had persistent low-titer inhibitors. Within the first 3 years of follow-up, immune tolerance induction (ITI) was equally implemented in around 80% of low-and high-titer patients but it was started later in children with high-titers (median time to ITI start 4.5 vs 0.3 months; p100 IU/kg/day) with an OR of 3.9 (95%CI 1.5-10.0), independent from the effects of F8 mutation type (adjusted OR 3.6, 95%CI 1.4-9.8) and family history of inhibitors (adjusted OR 6.7, 95%CI 1.1-42.6). No difference was found by comparing the use of daily versus non-daily ITI. In conclusion, in a cohort of 260 children with severe hemophilia A and inhibitors, 49% presented with low-titers at diagnosis and 46% of them progressed to high-titers during follow-up. Progression to high-titer inhibitors was associated with the use of high-dose ITI. These results suggest that intensive ITI should be avoided as initial strategy in low-titer inhibitor patients. Disclosures Mancuso: Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sobi/Biogen Idec: Consultancy, Speakers Bureau; Novo Nordisk: Consultancy, Speakers Bureau; CSL Behring: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Baxalta: Consultancy, Speakers Bureau; Bayer Healthcare: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kedrion: Consultancy. Fischer:Wyeth/Pfizer: Research Funding; Biogen: Consultancy; NovoNordisk: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Biotest Octapharma: Speakers Bureau; CSL Behring: Speakers Bureau; Baxter: Consultancy, Research Funding, Speakers Bureau; Freeline: Consultancy; Bayer: Consultancy, Research Funding, Speakers Bureau. Santagostino:Octapharma: Consultancy; Novo Nordisk: Consultancy; Kedrion: Consultancy; Sobi: Consultancy; Biogen Idec: Consultancy; Roche: Consultancy; Grifols: Consultancy; Pfizer: Consultancy; Baxalta: Consultancy; CSL Behring: Consultancy; Bayer: Consultancy. Escuriola:Baxalta, now part of Shire: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Investigator Clinical Studies, Research Funding; Bayer: Consultancy, Honoraria, Research Funding; Biotest: Consultancy, Honoraria, Research Funding; CSL Behring: Consultancy, Honoraria, Research Funding; Grifols: Consultancy, Honoraria, Research Funding; Octapharma: Consultancy, Honoraria, Research Funding; NovoNordisk: Consultancy, Honoraria, Research Funding. Liesner:BPL: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Speakers Bureau; Cangene: Research Funding; CSL Behring: Consultancy, Honoraria, Research Funding; Baxalta Innovations GmbH, now a part of Shire: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; SOBI: Consultancy, Honoraria, Research Funding, Speakers Bureau; Octapharma: Consultancy, Honoraria, Research Funding, Speakers Bureau; Biogen: Consultancy, Honoraria, Research Funding; Grifols: Consultancy, Honoraria. Nolan:Sobi: Research Funding; Biogen: Research Funding.

SummaryMany studies have reported an increased incidence of inhibitors in previously untreated patients (PUPs) with severe haemophilia A after the introduction of recombinant products. It was the objective of this study to investigate whether the inhibitor incidence has increased between 1990 and 2009 in an unselected cohort of PUPs with severe haemophilia A (FVIII < 1 %). Patients were consecutively recruited from 31 haemophilia treatment centres in 16 countries and followed until 50 exposure days or until inhibitor development. Inhibitor development was studied in five-year birth cohorts comparing cumulative incidences. Furthermore the risk for inhibitor development per five-year birth cohort was studied using multivariable Cox regression, adjusting for potential genetic and treatment-related confounders. A total of 926 PUPs were included with a total cumulative inhibitor incidence of 27.5 %. The inhibitor incidence increased from 19.5 % in 1990-1994 (lowest) to 30.9 % in 2000-2004 (highest; p-value 0.011). Low titre inhibitor incidence increased from 3.1 % in 1990-1994 to 10.5 % in 2005-2009 (p-value 0.009). High titre inhibitor incidences remained stable over time. After 2000, risk of all inhibitor development was increased with adjusted hazard ratios 1.96 (95 % CI 1.06-2.83) in 2000-2004 and 2.34 (1.42-4.92) in 2005-2009. Screening for inhibitors was intensified over this 20-year study period from a median of 1.9 to 2.9 tests/year before 2000 to 2.7 to 4.3 tests/ year after 2000. In conclusion, the cumulative inhibitor incidence has significantly increased between 1990 and 2009. The high titre inhibitor incidence has remained stable.