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01 april 2023, Item does not contain fulltext, BACKGROUND: Accurate measurements of coagulation factor activity form an essential part of hemophilia management and are performed by the one-stage or chromogenic assay. Current literature suggests that approximately one-third of persons with nonsevere hemophilia A exhibit assay discrepancy, albeit with a high variability between studies. Such data are scarce in nonsevere hemophilia B. OBJECTIVES: To investigate the extent of factor VIII/IX one-stage and chromogenic assay discrepancy in moderate and mild hemophilia A and B. METHODS: Persons with previously diagnosed nonsevere hemophilia A and B with a factor level of 2 to 35 IU/dL were included from the international DYNAMO cohort study. Central measurements of the factor VIII and IX activity levels were performed by the one-stage and chromogenic assay. Relative and absolute discrepancy definitions were used, with the International Society on Thrombosis and Haemostasis-Scientific and Standardization Committee proposed ratio of >2.0 or <0.5 being the primary outcome. Discrepancy was also evaluated in a subgroup of 13 persons with mutations previously associated with discrepancy (≥3 cases reported in literature). RESULTS: A total of 220 persons were included, of whom 3 (1%) showed assay discrepancy: 2/175 hemophilia A and 1/45 hemophilia B. Six persons (3%) exhibited an absolute difference >10 IU/dL between the assay results. In addition, with more lenient definitions, over 90% of participants (n = 197) had no discrepant results. Only 1 out of 13 persons with a mutation previously associated with discrepancy had significant assay discrepancy. CONCLUSION: Little assay discrepancy was observed despite the presence of mutations previously associated with discrepancy, suggesting that the presence and magnitude of assay discrepancy are largely determined by laboratory variables.

01 september 2023, Contains fulltext : 295967.pdf (Publisher’s version ) (Open Access), INTRODUCTION: Off-label drug use in the paediatric population is common, and the lack of high-quality efficacy studies poses patients at risk for failing pharmacotherapy. Next to efficacy studies, pharmacokinetic (PK) studies are increasingly used to inform paediatric dose selection. As resources for paediatric trials are limited, we aimed to summarize existing PK and efficacy studies to identify knowledge gaps in available evidence supporting paediatric dosing recommendations, thereby taking paediatric cardiovascular drugs as proof of concept. METHODS: For each cardiovascular drug, paediatric indication and prespecified age group, together comprising one record, the authorized state was assessed. Next, for off-label records, the highest level of evidence was scored. High-quality efficacy studies were defined as meta-analysis or randomized controlled trials. Other comparative research, noncomparative research or consensus-based expert opinions were considered low quality. The level of evidence for PK studies was scored per drug and per age group, but regardless of indication. RESULTS: A total of 58 drugs included 417 records, of which 279 (67%) were off-label. Of all off-label records, the majority (81%) were not supported by high-quality efficacy studies, but for 140 of these records (62%) high-quality PK studies were available. CONCLUSION: We demonstrated that for the majority of off-label cardiovascular drugs, only low-quality efficacy studies were available. However, high-quality PK studies were frequently available. Combining these PK data with extrapolation of efficacy data from adults may help to close the current information gap and prioritize the drugs for which clinical studies and safety data are urgently needed.

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Severe congenital protein C deficiency (SCPCD) is rare and there is currently substantial variation in the management of this condition. A joint project by three Scientific and Standardization Committees of the ISTH: Plasma Coagulation Inhibitors, Pediatric/Neonatal Thrombosis and Hemostasis, and Women's Health Issues in Thrombosis and Hemostasis, was developed to review the current evidence and help guide on diagnosis and management of SCPCD. We provide a summary of the clinical presentations, differential diagnoses, appropriate investigations to confirm the diagnosis, approaches for management of the acute situation, and options for long-term management including subsequent pregnancies. We finally provide a set of recommendations to help in this regard.

BACKGROUND: We aimed to describe the clinical presentation, risk of bleeding and recurrent thrombosis, and perioperative anticoagulant management of children with cerebral venous thrombosis (CVT) and an associated head or neck infection. METHODS: In this subgroup analysis of the EINSTEIN-Jr study, we included children with CVT and an associated head or neck infection who received therapeutic anticoagulants with either low-molecular-weight heparin (with or without subsequent vitamin K antagonists) or rivaroxaban for a period of 3 months. Analyses are descriptive. RESULTS: Of 74 included children, 59 (80%) had otomastoiditis, 21 (28%) a central nervous system infection, 18 (24%) sinusitis, and 9 (12%) another upper respiratory tract infection; 29 (39%) had infection of multiple regions of the head or neck. All 74 children received antibiotics and therapeutic anticoagulants; 41 (55%) underwent surgery, of whom 34 were diagnosed with CVT preoperatively. Anticoagulation was started before surgery in 12 children and interrupted 0-1 days prior to surgery. Anticoagulation was (re)started in all 34 children at a median of 1 day (interquartile range: 0-1) postoperatively, in therapeutic doses in 94%. Overall, one child (1%, 95% confidence interval: 0-7) had recurrent thrombosis, and one (1%, 95% confidence interval: 0-7) had major bleeding; neither was associated with surgery. At 3 months, no children had died, 3 (4%) had persistent focal neurologic deficits, and 2 (3%) had impaired vision. CONCLUSIONS: Children with CVT and an associated head or neck infection administered therapeutic anticoagulants generally had low risks of bleeding and thrombotic complications, including those who had surgical interventions with delay or interruption of anticoagulation.

Item does not contain fulltext, Detailed information on the onset, frequency, and severity of bleeding in nonsevere hemophilia is limited. We aimed to assess the bleeding phenotype of persons with nonsevere hemophilia and to analyze the association between baseline factor VIII/IX (FVIII/IX) levels and the joint bleeding rate. In the DYNAMO (Dynamic Interplay Between Bleeding Phenotype and Baseline Factor Level in Moderate and Mild Hemophilia A and B) study, an international multicenter cohort, we included males with nonsevere hemophilia (FVIII/IX, 0.02-0.35 IU/mL) aged 12 to 55 years. Information on age at first treated (joint) bleed, annual bleeding rates (ABRs), and annual joint bleeding rates (AJBRs) was collected from the medical files. The association between baseline FVIII/IX levels and the joint bleeding rate was assessed by using a frailty model for recurrent events. In total, 304 persons (70 with moderate hemophilia and 234 with mild hemophilia) were included. The median age was 38 years (interquartile range [IQR], 25-49 years), and the median baseline FVIII/IX level was 0.12 IU/mL (IQR, 0.05-0.21 IU/mL). In total, 245 (81%) persons had experienced at least 1 bleed, and 156 (51%) had experienced at least 1 joint bleed. The median age at first bleed and first joint bleed was 8 and 10 years, respectively. The median ABR and AJBR was 0.2 (IQR, 0.1-0.5) and 0.0 (IQR, 0.0-0.2). From baseline FVIII/IX levels 0.02 to 0.05 IU/mL to >0.25 IU/mL, the median ABR decreased from 0.6 (IQR, 0.2-1.4) to 0.1 (IQR, 0.0-0.2) and the AJBR from 0.2 (IQR, 0.0-0.4) to 0.0 (IQR, 0.0-0.0). Baseline FVIII/IX was inversely associated with the joint bleeding rate (P < .001). Low bleeding rates were observed in persons with nonsevere hemophilia. However, one-half of all adolescents and adults had experienced a joint bleed.

Anticoagulant treatment of pediatric cancer-associated venous thromboembolism (VTE) has not been prospectively evaluated. Management of anticoagulation for cancer-associated VTE is often challenged by drug interactions and treatment interruptions. A total of 56 of the 500 children (11.2%) with VTE who participated in the recent EINSTEIN-Jr randomized study had cancer (hematologic malignancy, 64.3%, solid malignant tumor, 35.7%). Children were allocated to either therapeutic-dose bodyweight-adjusted oral rivaroxaban (n=40) or standard anticoagulation with heparins, with or without vitamin K antagonists (n=16) and received a median of 30 concomitant medications. Based on sparse blood sampling at steady-state, pharmacokinetic (PK) parameters of rivaroxaban were derived using population PK modeling. During the 3 months of treatment, no recurrent VTE or major bleeding occurred (95% confidence interval, 0.0%-6.4%), and 3-month repeat imaging showed complete or partial vein recanalization in 20 and 24 of 52 evaluable children (38.5% and 46.2%, respectively). Anticoagulant treatment was interrupted 70 times in 26 (46.4%) children because of thrombocytopenia, invasive procedures, or adverse events, for a mean individual period of 5.8 days. Anticoagulant therapy was resumed in therapeutic doses and was not associated with thrombotic or bleeding complications. Rivaroxaban exposures were within the adult exposure range and similar to those observed in children with VTE who did not have cancer-associated VTE. Rivaroxaban and standard anticoagulants appeared safe and efficacious and were associated with reduced clot burden in most children with cancer-associated VTE, including those who had anticoagulant treatment interruptions. Rivaroxaban exposures were within the adult exposure range despite significant polypharmacy use. This trial was registered at www.clinicaltrials.gov as #NCT02234843.

Contains fulltext : 238745.pdf (Publisher’s version ) (Open Access), A drug is granted a license for use after a thorough assessment of risks and benefits based on high-quality scientific proof of its efficacy and safety. Many drugs that are relevant to children are not licensed for use in this population implying that a thorough assessment of risks and benefits in the pediatric population has not been made at all, implying a negative risk-benefit balance in children, or implying insufficient information to establish the risk-benefit balance. Use of drugs without positive assessment of risks and benefits exposes children to potential lack of efficacy, unknown toxicity, and harm. To aid guideline committees and individual prescribers, we here present a tutorial of the Benefit and Risk Assessment for Off-label use (BRAvO) decision framework. This pragmatic framework offers a structured assessment of benefits and risks of off-label drug use, including a clinical pharmacological based approach to age-appropriate dose selection. As proof of concept and to illustrate the practical use, we have applied the framework to assess benefits and risks of off-label use of ondansetron for gastroenteritis-induced nausea and vomiting. The framework could also guide decisions on off-label use in other special populations (e.g., pregnant women, elderly, obese, or critically ill patients) where off-label drug use is frequent, thereby contributing to effective and safe pharmacotherapy.

Pediatric thromboembolism is a rare and heterogenous disease. As a result, there is a paucity of knowledge with regard to natural history, management, and outcomes of most types of pediatric venous and arterial thromboembolism. International research collaboration is needed to fill these knowledge gaps. Not only randomized controlled trials, but also representative observational studies are required to answer all research questions. Therefore, the ISTH SSC Subcommittee on Pediatric and Neonatal Thrombosis and Hemostasis initiated the International Pediatric Thrombosis Network (IPTN). The aims of the IPTN include (1) development of the Throm-PED registry to facilitate international prospective observational studies, and (2) establishment of a network of pediatric thrombosis centers experienced in effectively conducting clinical trials and observational studies. The IPTN needs dedicated clinicians all over the world and several funding sources to obtain high-quality research data to reach its ultimate goal of improving care in children with thrombosis. The aim of this communication is to call for active participation in the IPTN to all physicians taking care of children with thrombosis worldwide.

1 januari 2020, Contains fulltext : 219893.pdf (Publisher’s version ) (Closed access), BACKGROUND: Treatment of venous thromboembolism in children is based on data obtained in adults with little direct documentation of its efficacy and safety in children. The aim of our study was to compare the efficacy and safety of rivaroxaban versus standard anticoagulants in children with venous thromboembolism. METHODS: In a multicentre, parallel-group, open-label, randomised study, children (aged 0-17 years) attending 107 paediatric hospitals in 28 countries with documented acute venous thromboembolism who had started heparinisation were assigned (2:1) to bodyweight-adjusted rivaroxaban (tablets or suspension) in a 20-mg equivalent dose or standard anticoagulants (heparin or switched to vitamin K antagonist). Randomisation was stratified by age and venous thromboembolism site. The main treatment period was 3 months (1 month in children <2 years of age with catheter-related venous thromboembolism). The primary efficacy outcome, symptomatic recurrent venous thromboembolism (assessed by intention-to-treat), and the principal safety outcome, major or clinically relevant non-major bleeding (assessed in participants who received >/=1 dose), were centrally assessed by investigators who were unaware of treatment assignment. Repeat imaging was obtained at the end of the main treatment period and compared with baseline imaging tests. This trial is registered with ClinicalTrials.gov, number NCT02234843 and has been completed. FINDINGS: From Nov 14, 2014, to Sept 28, 2018, 500 (96%) of the 520 children screened for eligibility were enrolled. After a median follow-up of 91 days (IQR 87-95) in children who had a study treatment period of 3 months (n=463) and 31 days (IQR 29-35) in children who had a study treatment period of 1 month (n=37), symptomatic recurrent venous thromboembolism occurred in four (1%) of 335 children receiving rivaroxaban and five (3%) of 165 receiving standard anticoagulants (hazard ratio [HR] 0.40, 95% CI 0.11-1.41). Repeat imaging showed an improved e