Effects of PK-guided prophylaxis on clinical outcomes and FVIII consumption for patients with moderate to severe Haemophilia A.

INTRODUCTION: In recent years, there has been increased focus on individualizing treatment for persons with hemophilia including pharmacokinetic-guided (PK) dosing. AIMS: In this retrospective study clinical outcomes before and after PK-guided prophylaxis were examined. MATERIALS AND METHODS: Eight Haemophilia Treatment Centres from the United States participated in the study and included 132 patients classified into two cohorts: those undergoing a PK-assessment for product switch (switchers) or to optimize treatment (non-switchers). Subset analyses for the two most common products and patients with dosing per prescription label were included for annual bleeding rates (ABR), mean weekly consumption outcomes, and annualized cost of prophylaxis. RESULTS: The most common products before and after index date were octocog alfa, rurioctocog alfa pegol, and efmoroctocog alfa. Seventy-four (56%) patients were identified as switchers and 58 (44%) patients were classified as non-switchers. The majority of patients (78.0%) experienced either a decrease in ABR post-index or maintained 0 ABR during pre- and post-index time periods, with similar proportions identified in both switchers (77.0%) and non-switchers (79.3%) populations. Non-switchers were identified as having no significant change in cost of therapy, while switchers experienced increased cost of therapy driven by higher price of extended half-life products. Within subset analyses, patients receiving rurioctocog alfa pegol and efmoroctocog alfa had mean ABR under 1 after index date. CONCLUSION: PK-guided prophylaxis has the potential to improve clinical outcomes without increase in cost of therapy for patients maintaining product and can aid in maintaining effective protection against bleeds in those switching product.

Hemophilia: A Review of Perioperative Management for Cardiac Surgery.

Hemophilia is an X-linked, recessive bleeding disorder. Improvements in factor replacement therapy and overall approach to hemophilia management have increased the lifespan and quality of life for patients with hemophilia. Thus, they are presenting for cardiac surgery related to age-related atherosclerosis, vascular disorders, and degenerative valvular disease. Although challenging, cardiac surgery can be performed safely with appropriate planning, using a multidisciplinary approach. This article provides a narrative review and framework for the perioperative management of patients with hemophilia A and B undergoing cardiac surgery.

Using an educational intervention to assess and improve disease-specific knowledge and health literacy and numeracy in adolescents and young adults with haemophilia A and B.

INTRODUCTION: Health literacy (HL) and health numeracy (HN) are underestimated barriers to treatment adherence in patients with haemophilia. AIM: To test the ability of an educational intervention to improve knowledge, HL, HN, adherence and joint health in adolescent and young adult (AYA) males with haemophilia. METHODS: We performed a longitudinal pilot study of 41 participants aged 12-21 years with haemophilia A or B during two clinic visits 6-12 months apart. The first visit included a comprehensive pre-intervention assessment: demographics, knowledge survey, Montreal Cognitive Assessment testing, 5-question tool to assess baseline HN, assessment of HL with the Rapid Estimate of Adolescent Literacy in Medicine tool, history of adherence and Haemophilia Joint Health Score (HJHS). An educational intervention using a visual aid explained basic pharmacokinetic (PK) concepts and personal teaching regarding haemophilia treatment regimens was used during this visit. The second visit included a post-intervention assessment: a reassessment of knowledge, HL, HN, HJHS, adherence to prescribed therapy and number of joint bleeds since the pre-intervention visit. RESULTS: Forty-one males with haemophilia A or B were enrolled in the study. Of these, 33 completed the post-intervention assessment. Knowledge (p = .002) and HN (p = .05) were significantly improved post-intervention, although the HL, number of joint bleeds, adherence to prescribed therapy and HJHS were not. CONCLUSIONS: Participants with low HL and/or HN may benefit from alternate methods of education such as audiovisual material. Education using audiovisual materials improved knowledge and HN in this study; however, this did not affect adherence to prescribed therapy.

Bypassing agent prophylaxis in people with hemophilia A or B with inhibitors.

BACKGROUND: People with hemophilia A or B with inhibitors are at high risk of bleeding complications. Infusion of bypassing agents, such as recombinant activated FVII (rFVIIa) and plasma-derived activated prothrombin complex concentrate, are suggested as alternative therapies to factor VIII (haemophilia A) or IX (haemophilia B) for individuals who no longer respond to these treatments because they develop inhibitory antibodies. The ultimate goal of treatment is to preserve the individual's joints, otherwise destroyed by recurrent bleeds. OBJECTIVES: To assess the effects of bypassing agent prophylaxis to prevent bleeding in people with hemophilia A or B and inhibitors. SEARCH METHODS: We searched for relevant studies from the Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also searched trial registries (16 February 2017) and bibliographic references of retrieved studies were reviewed for potential articles to be included in the review.Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Coagulopathies Trials Register: 12 December 2016. SELECTION CRITERIA: We included randomized and quasi-randomized controlled studies (cross-over or parallel design) evaluating the effect of prophylaxis treatment with bypassing agents compared with on-demand treatment, or studies evaluating the effects of high-dose compared with low-dose prophylaxis in males of any age with hemophilia with inhibitors. DATA COLLECTION AND ANALYSIS: Two authors independently selected studies and extracted data and assessed the risk of bias according to standard Cochrane criteria. They assessed the quality of the evidence using the GRADE criteria. MAIN RESULTS: We included four randomized studies (duration 7 to 15 months) involving 116 males. Risk of bias was judged to be high in two studies due to the open-label study design and in one study due to attrition bias.Two studies compared on-demand treatment to prophylaxis with bypassing agents. In one study (34 males) prophylaxis significantly reduced mean overall bleeding rates, MD - 7.27 (95% CI -9.92 to -4.62) (low quality evidence), mean number of overall bleeding events per month, MD -1.10 (95% CI -1.54 to -0.66), mean number of hemarthrosis, MD -6.60 (95% CI -9.32 to -3.88) (low quality evidence) and mean number of joints that had hemarthrosis, MD -0.90 (95% CI -1.36 to -0.44). The meta-analysis did not conclusively demonstrate significant benefit of prophylaxis on health-related quality of life as measured by Haem-A-QoL score, EQ-5D total score and utility score, EQ-5D VAS and SF-36 physical summary and mental summary score (low quality evidence for all health-related quality of life analyses).The remaining two studies compared dose regimens. The results from one study (22 males) did not conclusively demonstrate benefit or harm of high-dose versus low-dose recombinant activated factor VIIa (rFVIIa) as a prophylaxis for overall bleeding rate, MD -0.82 (95% CI -2.27 to 0.63) (moderate quality evidence), target joint bleeding rate, MD -3.20 (95% CI -7.23 to 0.83) (moderate quality evidence) and serious adverse events, RR 9.00 (95% CI, 0.54 to 149.50) (moderate quality evidence).The overall quality of evidence was moderate to low due to imprecision from limited information provided by studies with small sample sizes and incomplete outcome data in one study. AUTHORS' CONCLUSIONS: The evidence suggests that prophylaxis with bypassing agents may be effective in reducing bleeding in males with hemophilia with inhibitors. However, there is a lack of evidence for the superiority of one agent over the other or for the optimum dosage regimen. Further studies are needed to evaluate the benefits and harms of prophylaxis treatment on health-related quality of life, as well as the effects of dose of bypassing agents on the outcomes.

Outcomes of a Vial-Sparing Antithrombin III Protocol in Pediatric Extracorporeal Membrane Oxygenation.

Exogenous antithrombin III (AT3) may be administered to pediatric patients supported by extracorporeal membrane oxygenation (ECMO) to achieve a greater systemic response to heparin. Antithrombin III administration and dosing practices vary between ECMO centers. This study compared the outcomes of two different AT3 replacement protocols used by a single pediatric ECMO center for 47 patients between December 2013 and August 2021. In May 2016, a weight-based continuous infusion protocol (WBP) was transitioned to a vial-sparing protocol (VSP) as a cost-saving measure. No difference was observed in the percentage of heparin monitoring levels within goal range, with a median of 56.5% therapeutic levels on the WBP compared with a median of 60.7% on the VSP ( p = 0.170). No significant differences were observed in amount of exogenous blood products administered, number of hemorrhagic or thrombotic events, number of mechanical failures, or number of circuit changes required. The VSP resulted in fewer AT3 dispenses ( p < 0.001) and units dispensed ( p = 0.005), resulting in a significant median cost reduction from $15,610.62 on the WBP to $7,765.56 on the VSP ( p = 0.005). A vial-sparing AT3 replacement protocol resulted in significant cost savings with similar efficacy and safety outcomes.

Decreased Bleeding Rates in Patients with Hemophilia A Switching from Standard-Half-Life FVIII to BAY 94-9027 Prophylaxis.

BAY 94-9027 (damoctocog alfa pegol, Jivi) is an extended-half-life recombinant factor VIII (rFVIII) shown to be well-tolerated and efficacious in bleeding prevention in previously treated patients with severe hemophilia A. During the PROTECT VIII study, prophylaxis patients received BAY 94-9027 at intervals determined based on their bleeding phenotype, observed during a 10-week run-in treatment period with twice-weekly dosing. Those with ≤ 1 spontaneous joint or muscle bleed were randomized to either 45 to 60 IU/kg every 5 days or 60 IU/kg every 7 days; patients could increase dosing frequency to every 5 days or twice weekly in the case of bleeds. Those enrolled after the randomization arms were full, and those with ≥ 2 bleeds in the run-in period, received 30 to 40 IU/kg twice weekly. Patients completing the main study could receive open-label BAY 94-9027 in the extension phase. Dosing regimen, total, and joint annualized bleeding rates were analyzed over three periods: prestudy, main study, and extension. A total of 80 patients who were on prophylaxis treatment prior to and during the study and had prior bleed data available were evaluated in this post hoc analysis of PROTECT VIII. Most patients (> 80%) required fewer infusions with BAY 94-9027 prophylaxis versus their previous standard-half-life (SHL) rFVIII product. Lower bleeding and joint bleeding rates were observed over time from the prestudy to the extension study period in all treatment regimens. Compared with SHL FVIII, BAY 94-9027 prophylaxis allows patients to reduce infusion frequency with maintained or improved protection from bleeds.

A Real-World Analysis of Commonly Prescribed FVIII Products Based on U.S. Medical Charts: Consumption and Bleeding Outcomes in Hemophilia A Patients.

BACKGROUND: Patients with hemophilia A are commonly treated with replacement recombinant factor VIII (rFVIII) products, which can be standard-acting or long-acting. Long-acting products have modifications, offering the potential for reduced dosing frequency while maintaining therapeutic benefit. Extended dosing intervals reduce patient burden and can improve quality of life and adherence. OBJECTIVE: To assess real-world data for the use of 6 commonly prescribed standard-acting and long-acting FVIII products in the United States: octocog alfa, BAY 14-2222, BAY 81-8973, rVIII-SingleChain, rFVIIIFc, and polyethylene glycol (PEG)-rFVIII. We summarized annualized bleeding rates (ABRs), dosing frequency, and factor consumption in patients treated with each product, with subgroup analyses for patients with severe disease. METHODS: De-identified patient data were collected from 11 hemophilia treatment centers in the United States. Patients treated with octocog alfa, BAY 14-2222, BAY 81-8973, rVIII-SingleChain, rFVIIIFc, or PEG-rFVIII prophylaxis for ≥ 8 weeks at the time of data collection were included in the analysis. Among the 6 treatment groups, matching was attempted for patient age and disease severity where possible. RESULTS: Data were obtained for 240 patients, of whom 191 patients had severe disease. Patients receiving long-acting FVIII products were dosed less frequently than those receiving standard-acting FVIII products. The proportion of patients dosed 2 times weekly or less was 65.0%, 70.0%, 72.5%, 25.0%, 40.0%, and 47.5% with rVIII-SingleChain, rFVIIIFc, PEG-rFVIII, octocog alfa, BAY 14-2222, and BAY 81-8973, respectively. Median ABRs ranged from 2.0 to 3.0 (mean 2.6 to 4.4) across the 6 products for all patients and were similar for patients with severe disease (median 2.0 to 3.0 and mean 2.5 to 4.8). The proportion of patients experiencing 0 bleeding episodes ranged from 7.5% to 25.0% for all patients and 12.0% to 28.6% for patients with severe disease. For all patients, median (mean) weekly FVIII product consumption was lowest for rVIII-SingleChain among the 6 products (P = 0.045); 91.9 (91.1) IU per kg per week for rVIII-SingleChain, 108.5 (103.6) for rFVIIIFc, 97.6 (111.0) for PEG-rFVIII, 114.0 (117.5) for octocog alfa, 102.5 (102.6) for BAY 14-2222, and 95.1 (100.7) for BAY 81-8973. Similar differences in weekly consumption among the 6 products were observed for patients with severe disease (P = 0.014). CONCLUSIONS: Real-world data demonstrate that long-acting products may be beneficial compared with standard-acting products because of reduced dosing frequency while maintaining effectiveness. The 6 products evaluated showed statistically comparable ABRs and percentage of patients with 0 bleeds for all patients including those with severe disease. rVIII-SingleChain demonstrated lowest mean consumption for all patients, as well as for patients with severe hemophilia A, which may lead to potential savings in health care costs. DISCLOSURES: This study was funded by CSL Behring. Simpson reports consulting honoraria for participation in advisory boards for Bayer, CSL Behring, HEMA Biologics, Novo Nordisk, Octapharma, and Takeda and speakers bureau for Bayer and Novo Nordisk. Yan and Desai are employees of CSL Behring. Maro is an employee of Adivo Associates, which conducted the analyses for this study. Data were presented in part at the Hemostasis and Thrombosis Research Society; May 9-11, 2019; New Orleans, LA; at the International Society on Thrombosis and Haemostasis; July 6-10, 2019; Melbourne, Australia; and have been published in part in "Comparing Factor Use and Bleed Rates in U.S. Hemophilia A Patients Receiving Prophylaxis with 3 Different Long-Acting Recombinant Factor VIII Products," by Mindy L. Simpson, Vidhi Desai, Géraldine S. Maro, Songkai Yan (J Manag Care Spec Pharm. 2020;26[4]:504-12).

The Authors Respond.

DISCLOSURES: No funding was received for the writing of this letter. Simpson reports consulting honoraria for participation in advisory boards for Bayer, CSL Behring, HEMA Biologics, Novo Nordisk, Octapharma and Takeda, and speakers bureau for Bayer and Novo Nordisk; Yan and Desai are employees of CSL Behring; Maro is an employee of Adivo Associates.

Comparing Factor Use and Bleed Rates in U.S. Hemophilia A Patients Receiving Prophylaxis with 3 Different Long-Acting Recombinant Factor VIII Products.

BACKGROUND: Recombinant factor VIII (rFVIII) products have been developed with improved pharmacokinetics, offering some patients the potential to extend dosing intervals, thereby reducing their dosing frequency while minimizing the occurrence of bleeding events. No clinical trials have been conducted to compare the bleeding rates and use of these long-acting products. OBJECTIVES: To (a) assess real-world use of prophylaxis regimens in patients using 1 of 3 different long-acting products-rVIII-SingleChain, rFVIIIFc, or PEG-rFVIII; and (b) compare bleeding rates, dosing frequency, and factor consumption in 3 cohorts of patients. For rVIII-SingleChain patients, these measures were also compared with the prior products these patients used. METHODS: De-identified patient chart data were collected from 11 hemophilia treatment centers in the United States. Patients were included if they had been treated with rVIII-SingleChain, rFVIIIFc, or PEG-rFVIII prophylaxis for ≥ 8 weeks at the time of data collection. Matching for age and disease severity was attempted between the 3 patient groups. Data were also collected for patients who switched from their prior FVIII product to prophylaxis with rVIII-SingleChain. RESULTS: Data were obtained for 120 male patients. The majority of patients were dosing 2 times per week or less frequently (rVIII-SingleChain 65.0%, rFVIIIFc 70.0%, and PEG-rFVIII 72.5%). Annualized bleeding rates were comparable among the 3 cohorts, with median (mean) values of 2.0 (2.6) with rVIII-SingleChain and rFVIIIFc, and 3.0 (3.7) with PEG-rFVIII. The overall median (mean) FVIII consumption in IU per kg per week (IU/kg/week) was 91.9 (91.1) with rVIII-SingleChain, 108.5 (103.6) with rFVIIIFc, and 97.6 (111.0) with PEG-rFVIII, resulting in expected mean annual consumption of 322,140 IU, 361,816 IU, and 373,100 IU, respectively, for a 70 kg patient aged ≥12 years. The mean consumption was significantly different among the 3 products for all patients (P = 0.0164) and for those dosed 2 times per week (P < 0.0001). Among patients infusing 2 times per week, median (mean) consumption with rVIII-SingleChain was 83.8 (81.2) IU/kg/week, compared with 109.6 (104.4) IU/kg/week for rFVIIIFc and 92.1 (91.5) IU/kg/week for PEG-rFVIII. Additionally, switching from prophylaxis with prior FVIII products to rVIII-SingleChain increased the proportion of patients dosing ≤ 2 times per week (20% to 65%), decreased mean consumption (103.3 to 91.9 IU/kg/week; P = 0.0164), and maintained the mean annualized bleeding rates (2.9 to 2.6; P = 0.5665). CONCLUSIONS: Results for rVIII-SingleChain confirm the findings from its pivotal trial. Analyses of annualized bleeding rates demonstrate comparable clinical outcomes of rVIII-SingleChain to the other 2 long-acting products assessed. In patients aged ≥ 12 years, rVIII-SingleChain prophylaxis may result in an 11.0% and 13.7% lower mean factor consumption than rFVIIIFc and PEG-rFVIII, respectively, representing a potential cost-saving opportunity of 34% in both cases-at the current wholesale acquisition cost of the corresponding products. In addition, in patients using rVIII-SingleChain prophylactically, consumption was reduced compared with their prior products, while bleeding control was well maintained. DISCLOSURES: This study was funded by CSL Behring. Analyses were conducted by Adivo Associates. Maro is an employee of Adivo Associates. Desai and Yan are employees of CSL Behring. Simpson has received consulting honoraria for participation in advisory boards for CSL Behring, Genentech, Octapharma, and Bioverativ and speakers bureau for Bayer and Novo Nordisk. Data were presented in part at the Hemostasis and Thrombosis Research Society; May 9-11, 2019; New Orleans, LA, and at the International Society on Thrombosis and Haemostasis; July 6-10, 2019; Melbourne, Australia.

Comparing Physician and Patient Perspectives on Prophylactic Treatment with BAY 94-9027 for Severe Haemophilia A: A Post Hoc Analysis.

INTRODUCTION: BAY 94-9027 is a newly developed extended half-life product to treat haemophilia, allowing for fewer injections than with standard products. This post hoc analysis aimed to compare physicians' and patients' opinions on BAY 94-9027 prophylaxis, and explore how qualitative interview data is aligned with the data from the Haemophilia-specific Quality of Life questionnaire for Adults (Haemo-QoL-A). METHODS: Exploratory qualitative interviews were conducted with physicians and patients by phone upon the exit of patients from the PROTECT VIII extension phase following a semi-directed guide. In this post hoc analysis, all transcripts were reviewed and reported concepts were compared to assess the level of concordance between physicians and patients. These qualitative data were compared with the Haemo-QoL-A mean global and subscale scores at baseline and end of main phase (36 weeks later). RESULTS: Ten physicians and 16 patients (mean age 47 years) from Israel, the Netherlands and the USA were interviewed. Significant improvements were reported by all physicians from baseline [e.g. lower frequency of bleeds (80%), improvement in emotional functioning (90%)], which is in concordance with patients' reports. The improved confidence reported by physicians cascaded to greater participation in various activities, resulting in a better perceived emotional state and a significant improvement on the Haemo-QoL-A emotional impact subscale score (p = 0.04) between baseline and end of main phase. Most physicians (80%) reported improvement in bleed frequency, as patients did (88%). Improvement in physical functioning or mobility was not consistently reported in this 8-month study. CONCLUSION: Interviewed physicians and patients generally agreed on the beneficial impact of BAY 94-9027, specifically regarding the increased level of self-confidence in patients and its subsequent positive impact on patients' lives. These findings supported the observed improvement on the Haemo-QoL-A emotional impact subscale. Overall, this study highlights the concordance between physician and patient perspective on the positive experience with BAY 94-9027.

Population Pharmacokinetic Modeling Of On-Demand And Surgical Use Of Nonacog Beta Pegol (N9-GP) And rFIXFc Based Upon The paradigm 7 Comparative Pharmacokinetic Study.

AIM/OBJECTIVE: Understanding pharmacokinetic (PK) differences between standard and extended half-life (EHL) products is important, particularly for factor IX (FIX), where differences are more significant than for factor VIII. Two single-dose PK trials showed N9-GP achieves higher FIX levels and greater area-under-the-curve than pdFIX, rFIX, and rFIXFc through higher recovery and longer terminal half-life. In paradigm 7, N9-GP demonstrated consistently favorable PK characteristics compared with rFIXFc. Collins et al explored population PK differences between N9-GP and pdFIX/rFIX based upon paradigm 1 data. This analysis uses population PK models based upon the paradigm 7 trial. METHODS: 15 patients (21-65 years) with hemophilia B received single 50-IU/kg doses of N9-GP and rFIXFc ≥21 days apart. A population PK model developed from single-dose PK profiles simulated plasma FIX activity following dosing for surgery and on-demand treatment of bleeds. Simulations explored doses and frequencies required to sustain target World Federation of Hemophilia (WFH) factor activity levels. RESULTS: PK profiles of N9-GP and rFIXFc were described by one- and three-compartment models, respectively. Simulations predicted significantly reduced dosing frequency and consumption for N9-GP than rFIXFc. For severe bleeds, a single N9-GP dose (80 IU/kg) is sufficient to maintain WFH-recommended FIX levels, whereas multiple rFIXFc doses are required. For surgery, redosing in the first week with N9-GP is modeled at day 6 vs rFIXFc dosing at 6, 30, 54, 78, and 126 hrs. For life-threatening bleeds, N9-GP is required at days 0, 3, 6, 13, and 18 vs rFIXFc redosing after 6 hrs with 10 additional doses at 24-, 48-, and 72 hr intervals. CONCLUSION: PK modeling approaches based upon direct comparative studies offer insights into PK differences between EHL FIX products. Model simulations show N9-GP may allow on-demand treatment and perioperative management with 55-75% fewer injections and 65-74% lower overall factor concentrate consumption than rFIXFc.

Favorable pharmacokinetics in hemophilia B for nonacog beta pegol versus recombinant factor IX-Fc fusion protein: A randomized trial.

BACKGROUND AND OBJECTIVE: Nonacog beta pegol (N9-GP) and recombinant factor IX-Fc fusion protein (rFIXFc) are extended half-life rFIX compounds. We report the first single-dose pharmacokinetic trial of N9-GP and rFIXFc. PATIENTS/METHODS: Paradigm 7 was a multicenter, open-label, randomized, crossover trial in previously treated (>150 exposure days) adults with congenital hemophilia B (FIX activity ≤2%). Patients received single intravenous injections (50 IU/kg) of N9-GP and rFIXFc with at least 21 days between doses. Plasma FIX activity, predose, and at serial time points up to 240 hours postdose, was measured using validated one-stage clotting assays (SynthAFax for N9-GP; Actin FSL for rFIXFc) and a chromogenic assay (ROX factor IX) with normal human plasma as calibrator. The primary endpoint was area under the FIX activity-time curve from 0 to infinity, dose-normalized to 50 IU/kg (AUC0-inf,norm). RESULTS: Fifteen patients received study treatment. Based on FIX activity results from the one-stage clotting assays, estimated AUC0-inf,norm was significantly greater for N9-GP than rFIXFc (ratio: 4.39; P < 0.0001, based on a two-sided test on 5% significance level). In addition, N9-GP had a longer terminal half-life, two times higher incremental recovery at 30 minutes and maximum FIX activity (dose-normalized to 50 IU/kg) and six times higher FIX activity at 168 hours than rFIXFc. These findings were largely comparable with the chromogenic assay data and are consistent with published data for each compound. CONCLUSIONS: In this comparison, N9-GP demonstrated favorable pharmacokinetic characteristics versus rFIXFc, helping clinicians to understand differences between N9-GP and rFIXFc. REGISTRATION: This trial is registered with clinicaltrials.gov (NCT03075670) and the European Clinical Trials Database (EudraCT: 2016-001149-25).

Management of joint bleeding in hemophilia.

Hemarthrosis, the hallmark of severe hemophilia, is the major cause of serious bleeding events, disability and reduced quality of life in patients with factor VIII or factor IX deficiency. Joint bleeding is one of the greatest challenges confronting individuals treating hemophilia, and its economic impact is enormous. This article reviews the current management of hemophilic joint bleeding and discusses the potential impact of novel therapies.

Simultaneous thrombin and plasmin generation capacities in normal and abnormal states of coagulation and fibrinolysis in children and adults.

INTRODUCTION: Thrombin and plasmin are the key enzymes involved in coagulation and fibrinolysis, respectively. Plasma coagulative and fibrinolytic potentials in normal children and adults, and in representative pathologically altered hemostatic states, were evaluated via simultaneous assessment of thrombin and plasmin generation. MATERIALS AND METHODS: An assay of Simultaneous Thrombin and Plasmin generation (STP) was developed to measure thrombin and plasmin in plasma using individual fluorometric substrates. Coagulation is initiated with dilute tissue factor, phospholipid, and calcium in platelet-poor plasma; fibrinolysis is accelerated via tissue plasminogen activator (tPA). Abnormal states of hemostasis were investigated. RESULTS: STP assay reproducibility and normal adult and pediatric values for measured and calculated parameters have been established. Onset of both thrombin and plasmin generation was significantly delayed in children relative to adults (p<0.001) and the maximum amplitudes of thrombin and plasmin generation were less in children than adults (p<0.01). No significant differences were measured among pediatric age groups. The most profound impairments in thrombin generation were observed for extrinsic and common pathway factor deficiencies, with the exception of afibrinogenemia. Plasmin generation was severely impaired in deficiencies of fibrinogen and plasminogen as well as with decreased tPA reagent concentration and addition of aminocaproic acid. Plasmin generation was greatly enhanced by alpha-2-antiplasmin deficiency and excess tPA reagent. CONCLUSION: Simultaneous assessment of thrombin and plasmin generation in plasma shows promise for affording an enhanced understanding of overall coagulative and fibrinolytic functions in physiological and pathologically altered states of hemostasis in children and adults.