Building the foundation for a community-generated national research blueprint for inherited bleeding disorders: research priorities for mucocutaneous bleeding disorders.

BACKGROUND: Excessive or abnormal mucocutaneous bleeding (MCB) may impact all aspects of the physical and psychosocial wellbeing of those who live with it (PWMCB). The evidence base for the optimal diagnosis and management of disorders such as inherited platelet disorders, hereditary hemorrhagic telangiectasia (HHT), hypermobility spectrum disorders (HSD), Ehlers-Danlos syndromes (EDS), and von Willebrand disease (VWD) remains thin with enormous potential for targeted research. RESEARCH DESIGN AND METHODS: National Hemophilia Foundation and American Thrombosis and Hemostasis Network initiated the development of a National Research Blueprint for Inherited Bleeding Disorders with extensive all-stakeholder consultations to identify the priorities of people with inherited bleeding disorders and those who care for them. They recruited multidisciplinary expert working groups (WG) to distill community-identified priorities into concrete research questions and score their feasibility, impact, and risk. RESULTS: WG2 detailed 38 high priority research questions concerning the biology of MCB, VWD, inherited qualitative platelet function defects, HDS/EDS, HHT, bleeding disorder of unknown cause, novel therapeutics, and aging. CONCLUSIONS: Improving our understanding of the basic biology of MCB, large cohort longitudinal natural history studies, collaboration, and creative approaches to novel therapeutics will be important in maximizing the benefit of future research for the entire MCB community.

More people experience mucocutaneous bleeding (MCB), affecting tissues like skin and gums, than have hemophilia A or B. MCB is not understood as well as hemophilia. Common types of MCB include nosebleeds, bleeding gums, heavy menstrual bleeding, and digestive tract bleeding. Mucocutaneous inherited bleeding disorders include inherited platelet disorders, hereditary hemorrhagic telangiectasia (HHT), hypermobility spectrum disorders (HSD) and Ehlers-Danlos syndromes (EDS), von Willebrand Disease (VWD), and others. Diagnosing and treating MCB is complicated and sometimes medical providers dismiss the bleeding that patients report when they cannot find a medical explanation for it. Many people with mucocutaneous bleeding (PWMCB) do not receive the care they need; for example, women with VWD live with symptoms for, on average, 16 years before they are diagnosed in the US. This struggle to obtain care has important negative impacts on patients' physical and psychological health and their quality-of-life. The National Hemophilia Foundation (NHF), a large US bleeding disorders patient advocacy organization, set out to develop a National Research Blueprint for Inherited Bleeding Disorders focused on community priorities. They brought together a group of patients, providers, and researchers with MCB expertise to identify the research that would most improve the lives of PWMCB through targeted and accessible diagnostics and therapies. We report in this paper that research is needed to better understand the biology of MCB and to define the mechanisms of disease in these disorders. We also describe high priority research questions for each of the main disorders, novel therapeutics, and aging.

Consensus guidelines for diagnosis and management of anemia in epidermolysis bullosa.

BACKGROUND: Anemia is a common complication of severe forms of epidermolysis bullosa (EB). To date, there are no guidelines outlining best clinical practices to manage anemia in the EB population. The objective of this manuscript is to present the first consensus guidelines for the diagnosis and management of anemia in EB. RESULTS: Due to the lack of high-quality evidence, a consensus methodology was followed. An initial survey exploring patient preferences, concerns and symptoms related to anemia was sent to EB patients and their family members. A second survey was distributed to EB experts and focused on screening, diagnosis, monitoring and management of anemia in the different types of EB. Information from these surveys was collated and used by the panel to generate 26 consensus statements. Consensus statements were sent to healthcare providers that care for EB patients through EB-Clinet. Statements that received more than 70% approval (completely agree/agree) were adopted. CONCLUSIONS: The end result was a series of 6 recommendations which include 20 statements that will help guide management of anemia in EB patients. In patients with moderate to severe forms of EB, the minimum desirable level of Hb is 100 g/L. Treatment should be individualized. Dietary measures should be offered as part of management of anemia in all EB patients, oral iron supplementation should be used for mild anemia; while iron infusion is reserved for moderate to severe anemia, if Hb levels of > 80-100 g/L (8-10 g/dL) and symptomatic; and transfusion should be administered if Hb is < 80 g/L (8 g/dL) in adults and < 60 g/L (6 g/dL) in children.

Iron status and burden of anemia in children with recessive dystrophic epidermolysis bullosa.

BACKGROUND AND OBJECTIVES: To describe the prevalence, severity, and management of anemia in a cohort of children with recessive dystrophic epidermolysis bullosa (RDEB) and to highlight the use of soluble transferrin receptor (sTfR) to diagnose iron deficiency in this chronic inflammatory state. METHODS: We studied a cohort of 114 patients with RDEB followed at a pediatric hospital-based Epidermolysis Bullosa Center from 2010 to 2020; data were prospectively tracked in a comprehensive clinical database that captured all visits, laboratory tests, iron infusions, and transfusions. The primary outcome was occurrence of anemia, which was assessed by age and sex, with and without transfusion support. Secondary outcomes included iron status using a combination of ferritin and sTfR levels, the cumulative incidence of parenteral iron therapy and transfusions, and survival. RESULTS: In RDEB, anemia begins in the first year of life and becomes more frequent and severe with age. The prevalence of iron deficiency anemia (IDA) estimated by ferritin was 33.6% (37/110), but the sTfR/log10 -ferritin ratio indicated a 1.5-fold higher true prevalence of IDA of 50.6% (41/81). 53.5% (61/114) received parenteral iron infusions, transfusions, or both. Higher ferritin was associated with earlier mortality. CONCLUSIONS: Individuals with RDEB have a high burden of anemia (IDA and anemia of inflammation) that requires frequent medical interventions. The sTfR/log10 -ferritin ratio improves the detection of iron deficiency in the context of inflammation and guides therapy.

Improving bleeding disorder treatment log adherence: An application of the information-motivation-behavioral skills model.

INTRODUCTION: For people with severe bleeding disorders (PwBD) who are prescribed home treatment, treatment logs are an important part of the management of their care. Treatment logs provide a clinical picture of the home treatment regimen and can serve as a communication tool between the medical team and the person with a bleeding disorder. Most importantly, treatment logs allow for the adjustment of the treatment dose and frequency to prevent bleeding episodes. Yet, a large number of PwBD do not complete treatment logs. AIMS: We aimed to develop and implement interventions to increase adherence rates of treatment log completion in PwBD on a home treatment regimen by at least 20% over 2 years. METHODS: We conducted a quality improvement initiative from 2019-2022 involving developing and implementing interventions that were guided by the application of the Information-Motivation-Behavioural Skills Model. Examples of interventions included: the development of educational materials on the different methods of log completion and interactive discussions that involved a patient-driven decision of selecting a treatment log method. Data on the implementation of the theoretically-based interventions as well as outcome data on the success of treatment log completion was reviewed monthly. RESULTS: Following the application of the Information-Motivation-Behavioural Skills Model on the designed and implemented interventions, there was a 20% increase in individuals' adherence with treatment logs completion (N = 68). CONCLUSION: Treatment logs are an important piece of a PwBDs' prescribed home treatment regimen. Quality improvement interventions promoted increased treatment log adherence for PwBDs'prescribed prophylactic home treatment.

Moderate-intensity aerobic exercise vs desmopressin in adolescent males with mild hemophilia A: a randomized trial.

Persons with mild hemophilia A (HA) may use intranasal desmopressin prior to sports participation. Desmopressin is expensive and can cause vomiting, headache, palpitation, and occasionally seizures. Our group has previously documented a 2.3-fold increase in factor VIII activity (FVIII:C) in adolescents with mild HA after moderate-intensity aerobic exercise. Herein, we report principal findings of a randomized trial of intranasal desmopressin vs a standardized, moderate-intensity aerobic exercise regimen in adolescents with mild HA. Our primary objective was to compare the change in FVIII:C associated with these 2 interventions. We also examined changes in hemostatic parameters arising from their sequential administration. The study was conducted simultaneously at the Hospital for Sick Children, Canada, and Nationwide Children's Hospital, USA. Thirty-two eligible male adolescents (mean age ± standard deviation: 16.1 ± 2.6 years) with mild HA (mean baseline FVIII:C: 27.9% ± 18.4%) were randomized to 1 of 4 study arms (desmopressin followed by exercise, desmopressin alone, exercise followed by desmopressin, and exercise alone). Blood work was obtained at baseline and at 3 subsequent time-points. Participants randomized to exercise cycled on an ergometer for approximately 12 minutes, with the final 3 minutes at 85% of their predicted maximum heart rate. Standard weight-based dosing of desmopressin was used. Mean immediate increase in FVIII:C was 1.7-fold with exercise compared with 1.9-fold with desmopressin (noninferiority, P = .04). Exercise-induced improvement in hemostatic parameters including FVIII:C was brief compared with more sustained improvements seen with desmopressin. More than 60% of participants randomized to receive both exercise and desmopressin achieved normal (>50%) FVIII:C, 75 and 135 minutes into the study protocol.

Quality of life in a large multinational haemophilia B cohort (The B-Natural study) - Unmet needs remain.

INTRODUCTION: The B-Natural study is a multicentre, multinational, observational study of haemophilia B (HB) designed to increase understanding of clinical manifestations, treatment and quality of life (QoL). AIM: To characterise and compare QoL in HB across disease severity groups and individuals with inhibitors to identify gaps in treatment. METHODS: A total of 224 individuals from 107 families were enrolled from a total of 24 centres in North America (n = 16), Europe (n = 7) and Asia (n = 1). Of these, 68 (30.4%) subjects had severe (<1 IU/dL), median age 15.6 years, 114 (50.9%) moderate (1-5 IU/dL), age 13.3 years, and 42 (18.8%) mild (>5-< 40 IU/dL), age 12.1 years, disease. Twenty-nine participants had inhibitors or a history of inhibitors. Three versions of the EQ-5D instrument were used as a measure of QoL: proxy (ages 4-7), youth (ages 8-15) and self (age 16+). Each instrument included a visual analogue scale ranging from 100 (best health) to 0 (worst health) to assess current day's health (EQ VAS). Range-of-motion (ROM) for elbows, knees and ankles was assessed using a four-point scale, from which a composite score was calculated. RESULTS: In all severity groups, a proportion of subjects showed less than optimal QoL. The majority of the mild and moderate severe participants reported a normal EQ-5D health profile (79% and 72%, respectively), whereas about half (47%) of the severe participants and only 13% of the inhibitor participants reported this profile. CONCLUSION: The B-Natural study reveals impacted QoL in all disease severities of HB including those with inhibitors. Unmet needs remain and include nonsevere HB.

Correlation among Hemolysis Biomarkers in Pediatric Patients Undergoing Extracorporeal Membrane Oxygenation.

Hemolysis is a common complication associated with mortality on extracorporeal membrane oxygenation (ECMO). Plasma-free hemoglobin (PFH) is the most commonly used biomarker reported for hemolysis on ECMO. This test is not readily available at all institutions, and other more readily available tests may indicate hemolysis nearly as well or as well as PFH. The purpose of this study was to study the correlation of other biomarkers of hemolysis to PFH on ECMO. All patients younger than 21 years placed on ECMO in a quaternary children's hospital between January 2013 and December 2016 were included in the study; biomarkers (urine hemoglobin [U-Hb], PFH, lactate dehydrogenase [LDH], aspartate aminotransferase [AST], gross hemolysis, and red cell distribution width (RDW)) were collected from the medical record. Descriptive statistics and repeated bivariate analyses were determined using SPSS 22.0. The median age on day 0 of ECMO was 29 days (.08 years) (IQR: 2; 319 days (.005; .875 years)). The median weight was 3.9 kg (IQR: 2.8; 8.6), and the median total duration of the ECMO run was 10.48 days (IQR: 4.25; 14), with 82% of all the patients being on venoarterial ECMO. There was no correlation between hematuria on urinalysis and the level of PFH (p = .338). There was a statistically significant positive correlation between PFH and the following respective biomarkers: gross hemolysis on the routine chemistry studies (p < .01, Rho = .439), AST (p < .01, Rho = .439), RDW (p < .01, Rho = .190), LDH (p < .01, Rho = .584), and AST (when associated elevated alanine transaminase (ALT) levels were censored) (p < .01, Rho = .552). U-Hb correlated poorly with PFH. The serum biomarkers AST (in the absence of ALT elevation) and LDH can be useful surrogates for PFH to quantify hemolysis on ECMO in pediatric patients.

Pediatric May-Thurner Syndrome-Systematic review and individual patient data meta-analysis.

BACKGROUND: The outcomes of deep vein thrombosis (DVT) in children with May-Thurner Syndrome (MTS) remain unclear. OBJECTIVES: This systematic review and patient-level meta-analysis aims to describe the outcomes of children with MTS presenting with DVT. METHODS: A systematic review of the published literature was performed. Data related to patients <18 years diagnosed with MTS and DVT was extracted. Risk of bias was assessed using the Murad criteria. Outcomes included vessel patency post-treatment, DVT recurrence, and post-thrombotic syndrome (PTS). Predictive and explanatory models were developed for these outcomes. RESULTS: In total, 109 cases were identified (age range 4-17 years; 77 females) in 28 studies; 75% of patients had ≥1 additional risk factor for DVT. PTS was seen in 61% of patients, DVT recurrence in 38%, and complete vessel patency post-treatment in 65%. The models developed to predict and explain PTS performed poorly overall. Recurrent thrombosis (adjusted for age and patency) predicted PTS (odds ratio [OR] 3.36, 95% confidence interval [CI] 1.28-8.82). DVT management strategies (adjusted for age and DVT characteristics) predicted vessel patency (OR 2.10, 95% CI 1.43-3.08). Lack of complete vessel patency (adjusted for age and thrombophilia) predicted recurrent DVT (OR 2.70, 95% CI 1.09-6.67). Sensitivity analyses showed the same direction of effects for all outcomes. CONCLUSIONS: PTS and DVT recurrence occur frequently in pediatric MTS. PTS prediction is complex and it was not possible to identify early predictors to guide clinical practice. Use of imaging-guided therapy and thrombus burden predicted venous patency, and lack of patency predicted DVT recurrence.

Natural history study of factor IX deficiency with focus on treatment and complications (B-Natural).

INTRODUCTION: Haemophilia B (HB) is less well studied than haemophilia A (HA); despite similarities between the two inherited bleeding disorders, important differences remain that require further research. AIM: B-Natural is a multi-centre, prospective, observational study of HB, designed to increase understanding of clinical manifestations, treatment, quality-of-life (QoL), inhibitor development, immune tolerance induction (ITI) outcome, renal function and create a biorepository for future investigations. METHODS: Participants include sibling pairs/groups without a current/history of inhibitors and singletons or siblings with a current/history of inhibitors followed for six months. Demographics, medical, social history and treatment were recorded. A physical examination including joint range of motion (ROM) was performed; QoL was assessed. Samples were collected for F9 gene mutation, HLA typing, non-inhibitory antibodies and renal function testing. RESULTS: Twenty-four centres enrolled 224 individuals from 107 families including 29 with current/history of inhibitors. Of these, 68, 30.4%, had severe (<1% FIX level of normal); 114, 50.9%, moderate (1%-5%); and 42, 18.8%, mild (>5-<40%) disease. At enrolment, 53.1% had 50 + exposure days to exogenous FIX. Comparison of joint scores showed significant (P < .05) differences between those with severe (with/without inhibitors), and those with moderate/mild disease. The majority with severe disease, 80.0% with current/history of inhibitors and 64.3% of those without, were treated with prophylaxis. CONCLUSION: B-Natural provides data supporting an increased understanding of HB and its impact throughout life. The need for optimal disease control to normalize physical and psychosocial outcomes is underscored, and further analyses will contribute to an increased understanding of critical issues in HB.

Enteral iron absorption in patients with recessive dystrophic epidermolysis bullosa.

BACKGROUND/OBJECTIVES: To determine whether iron was being enterally absorbed in anemic patients with recessive dystrophic epidermolysis bullosa (RDEB). METHODS: Anemic patients with RDEB who were refractory or had poor adherence to oral or gastrostomy-given iron underwent enteral iron absorption challenges. Subjects were given 2 mg/kg of elemental iron. Successful iron absorption was defined as a two- to threefold increase of serum iron or a rise to above 100 µg/dL. RESULTS: Nine of 12 iron challenges did not show increased iron absorption. Only three of the ten subjects demonstrated elevated iron absorption. All patients had elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), low serum albumin, and hemoglobin levels. Eight challenges were in patients with elevated soluble transferrin receptor (STFR)/log ferritin levels, indicating iron deficiency. The three challenges with elevated iron absorption also had elevated STFR/log ferritin as well as elevated ESR and CRP, but these inflammatory markers were, in general, less elevated than those in non-absorbers. CONCLUSIONS: Enteral iron is routinely prescribed for anemic patients with RDEB assuming a component of iron deficiency. Adherence to enteral iron tends to be unreliable due to unpalatable taste and gastrointestinal complaints. Enteral iron absorption tests are relatively noninvasive and appear to be well tolerated. Poor gastrointestinal iron absorption may be an important factor in failure to improve anemia in RDEB enterally. It may be prudent to test patients with RDEB who are anemic and not responding well to conventional iron supplements with iron absorption tests and to consider replacement with intravenous iron in iron-deficient patients.

Non-transfusion-dependent ß-Thalassemia Because of a Single ß-Thalassemia Mutation and Coinherited α-Globin Gene Triplication: Need for Increased Awareness to Prevent Incorrect and Delayed Diagnosis.

The thalassemias are genetically complex and usually autosomal recessive. We describe 5 unrelated individuals with non-transfusion-dependent ß-thalassemia (NTDT), some with apparently dominant transmission, because of a single ß-thalassemia mutation coinherited with a triplicated α-globin locus. Each had an initial, incorrect diagnosis of ß-thalassemia trait. The correct diagnosis of NTDT was made at a mean of 7 years of age. Despite reports of this compound genotype causing NTDT, it remains unfamiliar to many clinicians. To increase awareness, we highlight its varied and sometimes subtle clinical and laboratory features and the need for comprehensive genetic testing for timely and correct diagnosis.

Treatment of Pediatric Venous Thromboembolism.

GUIDELINE TITLE: American Society of Hematology 2018 Guidelines for the management of venous thromboembolism: treatment of pediatric venous thromboembolism DEVELOPER: The American Society of Hematology multidisciplinary subcommittee RELEASE DATE: November 27, 2018 FUNDING SOURCE: American Society of Hematology PRIOR VERSION: N/A TARGET POPULATION: less than 18 years of age.

Antiphospholipid syndrome in pediatric patients.

PURPOSE OF REVIEW: The purpose of this review is to summarize the diagnosis and management of the antiphospholipid syndrome (APS) in children. RECENT FINDINGS: APS is a rare, acquired autoimmune systemic disease that can result in significant morbidity in children related to vascular thrombosis. The diagnosis and management of APS in children can be challenging due to a lack of validated diagnostic criteria and the rarity of the disease. In addition, many healthy children have transient circulating antiphospholipid antibodies without thrombotic complications. Nevertheless, epidemiological studies suggest that APS represents a greater relative proportion of thrombotic disease in children than it does in adults. Management of pediatric APS is largely inferred from adult data despite unique characteristics of pediatric APS. The current recommendations include long-term anticoagulation, which can be problematic in young, active individuals. There is little data on potential benefits of nonantithrombotic therapy in the management of pediatric APS. SUMMARY: Data on pediatric APS are limited, but evidence suggests that using current available diagnostic testing is valuable and, until further evidence is available, treating thrombotic complications with heparins or warfarin should be standard of care.

Clinical algorithm to manage anemia in epidermolysis bullosa.

Epidermolysis bullosa is a group of rare genetic disorders with multiple organ system involvement. In one severe form, recessive dystrophic epidermolysis bullosa, chronic anemia is common. This report outlines the multifactorial nature of anemia in recessive dystrophic epidermolysis bullosa and presents a practical clinical algorithm based on expert consensus for the diagnosis and treatment of anemia in recessive dystrophic epidermolysis bullosa.

Inferior vena cava atresia predisposing to acute lower extremity deep vein thrombosis in children: A descriptive dual-center study.

PURPOSE: Thrombosis in the healthy pediatric population is a rare occurrence. Little is known about the optimal treatment or outcomes of children with unprovoked acute lower extremity (LE) deep vein thrombosis (DVT) associated with atresia of the inferior vena cava (IVC). METHODS: We retrospectively analyzed the records of patients with acute LE DVT subsequently found to have IVC atresia who presented to two tertiary pediatric institutions between 2008 and 2016. Data were reviewed for thrombophilia risk factors, treatment, and outcomes. RESULTS: Eighteen patients, aged 13-18 years (median: 16 years), presenting with acute LE DVT were found to have IVC atresia. Three patients also presented with pulmonary embolism. Fourteen patients underwent site-directed thrombolysis in addition to anticoagulation. Five patients (28%) had confirmed or suspected recurrent thrombosis. Thirteen patients (72%) had no identified provocation for DVT. Ten patients (56%) had post-thrombotic syndrome, and 17 of 18 patients remain on indefinite anticoagulation. CONCLUSION: This study suggests that IVC atresia is a risk factor for LE DVT and pulmonary embolism in otherwise healthy children and highlights the importance of dedicated imaging of the IVC in young patients with unprovoked LE DVT. Indefinite anticoagulation may be considered in pediatric patients presenting with unprovoked thrombosis secondary to an atretic IVC.

Duration of anticoagulant therapy in pediatric venous thromboembolism: Current approaches and updates from randomized controlled trials.

INTRODUCTION: Compared with the incidence of venous thromboembolism in the adult population, pediatric VTE is rare. Yet, recent data suggest that the incidence of VTE in children is increasing, and little is known about the optimal duration of anticoagulation in pediatrics. Areas covered: This review summarizes current evidence-based adult recommendations and associated clinical trials from which current guidelines on the duration of anticoagulation in children have been extrapolated. It also discusses pediatric expert consensus-based guidelines and current pediatric clinical trials on duration of therapy in pediatric VTE. Expert commentary: The vast majority of pediatric VTE are provoked, and evidence on duration of anticoagulation for pediatric VTE is highly limited, but suggests that a maximum duration of 3 months is reasonable for most patients with provoked VTE, whereas longer duration is likely appropriate for unprovoked VTE. Whether shorter duration than 3 months is optimal for pediatric provoked VTE is as yet unclear. Results from the multinational randomized controlled trial studying the duration of anticoagulant therapy for provoked VTE in patients <21 years old (Kids-DOTT) will be critical to inform the future standard of care in pediatric VTE treatment.

Pediatric Thrombolysis: A Practical Approach.

The incidence of pediatric venous thromboembolic disease is increasing in hospitalized children. While the mainstay of treatment of pediatric thrombosis is anticoagulation, reports on the use of systemic thrombolysis, endovascular thrombolysis, and mechanical thrombectomy have steadily been increasing in this population. Thrombolysis is indicated in the setting of life- or limb-threatening thrombosis. Thrombolysis can rapidly improve venous patency thereby quickly ameliorating acute signs and symptoms of thrombosis and may improve long-term outcomes such as postthrombotic syndrome. Systemic and endovascular thrombolysis can result in an increase in minor bleeding in pediatric patients, compared with anticoagulation alone, and major bleeding events are a continued concern. Also, endovascular treatment is invasive and requires technical expertise by interventional radiology or vascular surgery, and such expertise may be lacking at many pediatric centers. The goal of this mini-review is to summarize the current state of knowledge of thrombolysis/thrombectomy techniques, benefits, and challenges in pediatric thrombosis.

A bleeding assessment tool correlates with intraoperative blood loss in children and adolescents undergoing major spinal surgery.

Screening laboratory studies for bleeding disorders are of little predictive value for operative bleeding risk in adults. Predicting perioperative bleeding in pediatric patients is particularly difficult as younger patients often have not had significant hemostatic challenges. This issue is distinctly important for high bleeding risk surgeries, such as major spinal procedures. The aim of this study was to determine if the score of a detailed bleeding questionnaire (BQ) correlated with surgical bleeding in pediatric patients undergoing major spinal surgery. A total of 220 consecutive pediatric patients (mean age 14.2years) undergoing major spinal surgery were administered the BQ preoperatively, as well as having routine screening laboratory studies (i.e., PT, aPTT, PFA) drawn. A retrospective analysis was conducted to determine if there was a correlation between either the results of the BQ and/or laboratory studies with operative outcomes. A BQ score>2 showed a strong positive correlation with intraoperative bleeding based on both univariate and multivariate analyses. In contrast, abnormalities in screening laboratory studies showed no significant correlation with operative bleeding outcomes. Relying on screening laboratory studies alone is inadequate. The BQ used here correlated with increased intraoperative hemorrhage, suggesting this tool may be useful for assessing pediatric surgical bleeding risk, and may also be useful in identifying a subset of patients with a very low bleeding risk that may not require laboratory screening.