| 1. |
- Andersson, Nadine G, et al.
(författare)
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Novel F8 and F9 gene variants from the PedNet Hemophilia Registry classified according to ACMG/AMP guidelines
- 2020
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Ingår i: Human Mutation. - : Hindawi Limited. - 1059-7794 .- 1098-1004. ; 41:12, s. 2058-2072
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Tidskriftsartikel (refereegranskat)abstract
- In hemophilia A and B, analysis of the F8 and F9 gene variants enables carrier- and prenatal diagnosis and prediction of risk for development of inhibitors. The PedNet Registry collects clinical, genetic and phenotypic data prospectively on >2000 children with hemophilia. The genetic reports of F8/F9 gene variants were classified uniformly to HGVS nomenclature and re-evaluated using international population- and disease-specific databases, literature survey and, where applicable, computational predictive programs. We report 88 novel variants in the F8 and F9 genes, 80 fulfilling criteria for class 5 (pathogenic), six for class 4 (likely pathogenic) and two fulfilling criteria for class 3 (variant of unknown significance) of the ACMG (American College of Medical Genetics and Genomics)/AMP (Association for Molecular Pathology) guidelines together with information on the respective phenotype and inhibitor formation. The study highlights the need to re-evaluate and update earlier genetic reports in hemophilia both locally but also in variant databases in the light of changed nomenclature and new guidelines. This article is protected by copyright. All rights reserved.
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| 2. |
- Berntorp, Erik, et al.
(författare)
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Haemophilia
- 2021
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Ingår i: Nature Reviews Disease Primers. - : Springer Science and Business Media LLC. - 2056-676X. ; 7:1
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Forskningsöversikt (refereegranskat)abstract
- Haemophilia A and B are rare congenital, recessive X-linked disorders caused by lack or deficiency of clotting factor VIII (FVIII) or IX (FIX), respectively. The severity of the disease depends on the reduction of levels of FVIII or FIX, which are determined by the type of the causative mutation in the genes encoding the factors (F8 and F9, respectively). The hallmark clinical characteristic, especially in untreated severe forms, is bleeding (spontaneous or after trauma) into major joints such as ankles, knees and elbows, which can result in the development of arthropathy. Intracranial bleeds and bleeds into internal organs may be life-threatening. The median life expectancy was ~30 years until the 1960s, but improved understanding of the disorder and development of efficacious therapy based on prophylactic replacement of the missing factor has caused a paradigm shift, and today individuals with haemophilia can look forward to a virtually normal life expectancy and quality of life. Nevertheless, the potential development of inhibitory antibodies to infused factor is still a major hurdle to overcome in a substantial proportion of patients. Finally, gene therapy for both types of haemophilia has progressed remarkably and could soon become a reality.
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| 3. |
- Berntorp, Erik, et al.
(författare)
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Models of prophylaxis.
- 2012
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Ingår i: Haemophilia. - : Wiley. - 1351-8216. ; 18 Suppl 4, s. 136-140
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Tidskriftsartikel (refereegranskat)abstract
- Summary: Long-term, continuous prophylaxis for haemophilia began at a modest scale during the 1950s and 1960s in Sweden and The Netherlands. In the face of high cost and impediments to the performance of longitudinal, well-designed studies, it was decades before prophylaxis was considered to be the best practice in countries that could afford the cost. In 2007 and 2011, the only prospective randomized studies ever performed confirmed what large cohort studies in Europe had long since shown. Today, focus is on when to start prophylaxis, dosing and when/if to stop. Retrospective comparisons of the Swedish and Dutch cohorts, where different strategies have been used, indicate that a costly, high-dose regimen improves outcome, but not dramatically. A prospective comparison is now underway. Treatment, clinical outcome, clotting factor consumption and socioeconomic parameters will be compared between the two strategies. Results are expected to provide greater insight into the long-term consequences of the different prophylactic treatment strategies. The economic justification for prophylaxis has been addressed in several studies with varying results. While the majority (implicitly) suggest that prophylaxis is not cost effective at conventional willingness to pay for additional units in health thresholds, their results vary markedly. Closer inspection suggests that the primary reasons results differ include different definitions of prophylaxis, clotting factor price, discount rates, choice of outcome measures and time horizon.
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| 4. |
- Björkman, Sven, et al.
(författare)
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Population pharmacokinetics of recombinant factor VIII : the relationships of pharmacokinetics to age and body weight
- 2012
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 119:2, s. 612-618
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Tidskriftsartikel (refereegranskat)abstract
- Comparison of the pharmacokinetics (PK) of a coagulation factor between groups of patients can be biased by differences in study protocols, in particular between blood sampling schedules. This could affect clinical dose tailoring, especially in children. The aim of this study was to describe the relationships of the PK of factor VIII (FVIII) with age and body weight by a population PK model. The potential to reduce blood sampling was also explored. A model was built for FVIII PK from 236 infusions of recombinant FVIII in 152 patients (1-65 years of age) with severe hemophilia A. The PK of FVIII over the entire age range was well described by a 2-compartment model and a previously reported problem, resulting from differences in blood sampling, to compare findings from children and adults was practically abolished. The decline in FVIII clearance and increase in half-life with age could be described as continuous functions. Retrospective reduction of blood sampling from 11 to 5 samples made no important difference to the estimates of PK parameters. The obtained findings can be used as a basis for PK-based dose tailoring of FVIII in clinical practice, in all age groups, with minimal blood sampling.
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| 5. |
- Bukkems, Laura H., et al.
(författare)
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Association between Sports Participation, Factor VIII Levels and Bleeding in Hemophilia A
- 2023
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Ingår i: Thrombosis and Haemostasis. - : Georg Thieme Verlag KG. - 0340-6245 .- 2567-689X. ; 123:03, s. 317-325
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundLittle is known on how sports participation affects bleeding risk in hemophilia. This study aimed to examine associations between sports participation, factor VIII (FVIII) levels and bleeding in persons with hemophilia A.MethodsIn this observational, prospective, single-center study, persons with hemophilia A who regularly participated in sports were followed for 12 months. The associations of patient characteristics, FVIII levels, and type/frequency of sports participation with bleeding were analyzed by repeated time-to-event modelling.ResultsOne hundred and twelve persons (median age: 24 years [interquartile range:16-34], 49% severe, 49% on prophylaxis) were included. During follow-up, 70 bleeds of which 20 sports-induced were observed. FVIII levels were inversely correlated with the bleeding hazard; a 50% reduction of the baseline bleeding hazard was observed at FVIII levels of 3.1 and a 90% reduction at 28.0 IU/dL. The bleeding hazard did not correlate with sports participation. In addition, severe hemophilia, prestudy annual bleeding rate, and presence of arthropathy showed a positive association with the bleeding hazard.ConclusionsThis analysis showed that FVIII levels were an important determinant of the bleeding hazard, but sports participation was not. This observation most likely reflects the presence of adequate FVIII levels during sports participation in our study. Persons with severe hemophilia A exhibited a higher bleeding hazard at a similar FVIII levels than nonsevere, suggesting that the time spent at lower FVIII levels impacts overall bleeding hazard. These data may be used to counsel persons with hemophilia regarding sports participation and the necessity of adequate prophylaxis.
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| 6. |
- Chowdary, Pratima, et al.
(författare)
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Modeling to Predict Factor VIII Levels Associated with Zero Bleeds in Patients with Severe Hemophilia A Initiated on Tertiary Prophylaxis
- 2020
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Ingår i: Thrombosis and Haemostasis. - : Georg Thieme Verlag KG. - 0340-6245 .- 2567-689X. ; 120:5, s. 728-736
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Tidskriftsartikel (refereegranskat)abstract
- Background: Factor VIII (FVIII) trough levels > 1 IU/dL in patients with severe hemophilia A receiving regular prophylaxis may optimize bleed protection. Objectives: In this post hoc analysis of patients receiving tertiary prophylaxis for approximately 1 year, the relationship between estimated FVIII levels and reported bleeds was investigated to predict the potential for zero bleeds. Methods: Sixty-three patients (median [range] age, 28 [7-59] years) with severe hemophilia A (229 bleeds) were included. FVIII levels at time of each bleed were estimated from single-dose individual pharmacokinetics. The highest estimated FVIII level at which patients experienced a bleed was considered the potentially effective trough level for that bleed type. Kaplan-Meier estimates of proportions of patients with no bleeds above certain estimated FVIII levels were determined. Those not experiencing a bleed in the trial were assumed to have a bleed at 0 IU/dL (pragmatic approach) or at their median trough level (conservative approach). Results: Kaplan-Meier estimates based on pragmatic approach predicted zero all bleeds, joint bleeds, and spontaneous joint bleeds in 1 year in 40, 43, and 63% of patients, respectively, when the potentially effective trough FVIII level was set at 1 IU/dL. Between 1 and 10 IU/dL, every 1 IU/dL rise in estimated FVIII level was associated with an additional 2% of patients having zero all bleeds. Conclusion: This post hoc analysis confirms benefits with trough levels of approximately 1 to 3 IU/dL in most patients starting tertiary prophylaxis; prophylaxis with higher trough levels may help patients to achieve zero bleeds.
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| 7. |
- de Kovel, Marloes S., et al.
(författare)
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Bleeding phenotype according to factor level in 825 children with nonsevere hemophilia : data from the PedNet cohort
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Ingår i: Journal of Thrombosis and Haemostasis. - 1538-7933.
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Tidskriftsartikel (refereegranskat)abstract
- Background: Information on bleeding phenotype in nonsevere hemophilia may be used to determine target factor levels for prophylaxis or gene therapy in severe hemophilia. Objectives: To assess the association between endogenous factor level and bleeding phenotype in children with nonsevere (factor [F]VIII/FIX activity 1%-25%) hemophilia A (HA) and B without prophylaxis. Methods: Data on annualized bleeding rate (ABR), annualized joint bleeding rate (AJBR), and onset of bleeding were extracted from the international PedNet cohort including children born since 2000. Mean ABR and AJBR were modeled and compared according to FVIII/FIX endogenous activity (1%-2%, 3%-5%, 6%-10%, 11%-15%, 16%-20%, and 21%-25%) using negative binomial regression. Onset of bleeding was analyzed using Kaplan–Meier survival curves. Results: Eight hundred twenty-five children (40% with moderate hemophilia; 87% with HA) with median follow-up of 7.4 years/child were included. The median age at onset of bleeding and median bleeding rates changed with increasing endogenous activity. From endogenous FVIII 1% to 2% to 21% to 25%, the age at onset of bleeding changed from a median of 1.4 to 14.2 years, ABR from 1.6 to 0.1/y, and AJBR from 0.5 to 0.0/y. From endogenous FIX 1% to 2% to 16% to 25%, the onset of bleeding changed from a median of 1.7 to 6.1 years, ABR from 0.5 to 0.1/y, and AJBR from 0.1 to 0.0/y. The negative correlation between AJBR and factor level was most strongly pronounced up to a factor level of 6% in HA and hemophilia B. Conclusion: Endogenous factor activity of >5% was identified as a threshold to significantly lower joint bleeding rate, while FVIII levels >15% and FIX levels >10% were sufficient to achieve the goal of 0 bleeds in this pediatric cohort.
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| 8. |
- Fischer, Kathelijn, et al.
(författare)
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Intermediate- dose versus high-dose prophylaxis for severe hemophilia: comparing outcome and costs since the 1970s
- 2013
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 122:7, s. 1129-1136
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Tidskriftsartikel (refereegranskat)abstract
- Prophylactic treatment in severe hemophilia is very effective but is limited by cost issues. The implementation of 2 different prophylactic regimens in The Netherlands and Sweden since the 1970s may be considered a natural experiment. We compared the costs and outcomes of Dutch intermediate-and Swedish high-dose prophylactic regimens for patients with severe hemophilia (factor VIII/IX < 1 IU/dL) born between 1970 and 1994, using prospective standardized outcome assessment and retrospective collection of cost data. Seventy-eight Dutch and 50 Swedish patients, median age 24 years (range, 14-37 years), were included. Intermediate-dose prophylaxis used less factor concentrate (median: Netherlands, 2100 IU/kg per year [interquartile range (IQR), 1400-2900 IU/kg per year] vs Sweden, 4000 IU/kg per year [IQR, 3000-4900 IU/kg per year]); (P <.01). Clinical outcome was slightly inferior for the intermediate-dose regimen (P <.01) for 5-year bleeding (median, 1.3 [IQR, 0.8-2.7] vs 0 [IQR, 0.0-2.0] joint bleeds/y) and joint health (Haemophilia Joint Health Score > 10 of 144 points in 46% vs 11% of participants), although social participation and quality of life were similar. Annual total costs were 66% higher for high-dose prophylaxis (mean, 180 [95% confidence interval, 163 -196] 3 US$ 1000 for Dutch vs 298 [95% confidence interval, 271-325]) x US$ 1000 for Swedish patients; (P <.01). At group level, the incremental benefits of high-dose prophylaxis appear limited. At the patient level, prophylaxis should be tailored individually, and many patients may do well receiving lower doses of concentrate without compromising safety.
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| 9. |
- Fischer, Kathelijn, et al.
(författare)
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Primary prophylaxis in haemophilia care : Guideline update 2016
- 2017
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Ingår i: Blood Cells, Molecules, and Diseases. - : Elsevier BV. - 1079-9796. ; 67, s. 81-85
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Tidskriftsartikel (refereegranskat)abstract
- This paper reviews the current status on recommendations or guidelines for primary prophylaxis based on recent published papers from organizations or group of experts as well as some original key papers. A rather uniform view exists that prophylaxis should be initiated at an early age before or after no more than a single joint bleed and, if possible, preferably be continued for life. The dose and dose frequency of prophylaxis is dependent on the goal of treatment, bleeding phenotype, compliance, venous access and economic resources in the health care system and should be tailored individually based on clinical outcome and pharmacokinetics. For children, the effectiveness of prophylaxis is more dependent on maintaining minimum trough levels than in adults. Novel extended half-life products are being introduced, which should not affect the decision on when to start prophylaxis nor the initial dose, but which may be helpful for patients with difficult venous access and which may enable higher trough levels of factor VIII.
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| 10. |
- Fischer, Kathelijn, et al.
(författare)
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Targeting Factor Replacement Therapy in Severe Hemophilia: Which Level Is Important?
- 2015
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Ingår i: Seminars in Thrombosis and Hemostasis. - : Georg Thieme Verlag KG. - 1098-9064 .- 0094-6176. ; 41:8, s. 860-863
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Tidskriftsartikel (refereegranskat)abstract
- The original aim of prophylactic replacement therapy was to convert the bleeding pattern of severe hemophilia to that of moderate hemophilia through regular infusions of clotting factor concentrates. However, targeting prophylaxis on minimum trough levels does not prevent all bleeding. At the group level, there is a clear association of factor levels with bleeding and outcome. But bleeding phenotype in individual patients shows large variation, independent of trough levels maintained. The association of peak levels with bleeding on prophylaxis is not established. Experience with surgery suggests that certain peak levels need to be achieved during other hemostatic challenges, such as playing sports. Individualization of prophylaxis should include timing of infusion according to special activities. The clinical relevance of factor levels is even more urgent since the recent introduction of long-acting clotting factor concentrates with their different pharmacokinetic profiles and the prospect of gene therapy resulting in constant factor levels. It should be considered that the success of any prophylactic regimen is also dependent on other factors, such as the age at initiation of prophylaxis, adherence, lifestyle, cartilage susceptibility, and the other components of the clotting system. Factor levels are thus an important but quite small piece in the total picture of treating hemophilia and we currently cannot identify a specific trough or peak level to use for monitoring. At the same time, knowledge of a patients' level during the infusion intervals may help to individualize and adjust treatment according to the clinical symptoms.
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