Considerations for instituting pediatric pulmonary embolism response teams: A tool kit.

The incidence of pediatric pulmonary embolism (PE) has increased by 200 % in the last decade, but at a single center, it is still infrequent. Given the unique epidemiologic features of pediatric PE, diagnosis is often delayed, and the management is empiric, based on individual physician experience or preference. Thus, there is a strong need for center-specific uniform management of pediatric PE patients. In adults, the development of pulmonary embolism response teams (PERTs) or PE critical care pathways has shortened the time to diagnosis and the initiation of definitive management. Evidence to support an improvement in PE outcomes after the development of PERTs does not exist in children. Nonetheless, we have summarized the practical practice guidelines that physicians and institutions can adopt to establish their institutional PERTs or critical pathways. We also provide strategies for resource-challenged institutions for partnering with centers with expertise in the management of pediatric PE.

Apixaban overdose in children: case report and proposed management. A brief communication from the Pediatric and Neonatal Thrombosis and Hemostasis SSC of ISTH.

Background: Direct oral anticoagulants are commonly prescribed for adults and increasingly also for children requiring anticoagulation therapy. While household medications should not be accessible to children, accidental, and intentional overdoses occur. Key Clinical Question: How should apixaban overdose in children be managed?. Clinical Approach: We present a case of an accidental overdose with the factor Xa antagonist apixaban in a young child and propose an approach to the management of cases of apixaban overdose in children. Conclusion: Given the increasing use of direct oral anticoagulants, it is important to have an approach to the management of overdose of these medications.

A post hoc analysis of PROTECT VIII kids assessing long-term efficacy and safety of damoctocog alfa pegol in adolescents with severe haemophilia A.

INTRODUCTION: The safety and efficacy of the extended half-life factor VIII (FVIII) product damoctocog alfa pegol (BAY 94-9027, Jivi®) has been demonstrated in the PROTECT VIII Kids study (NCT01775618), where male previously-treated patients (PTPs) aged <12 years old with severe haemophilia A and ≥ 50 exposure days (EDs) were treated prophylactically. The PROTECT VIII Kids extension study assessed the long-term safety and efficacy of damoctocog alfa pegol in the same population. AIM: To evaluate the long-term impact of damoctocog alfa pegol in a post hoc subgroup analysis of adolescent patients in the PROTECT VIII Kids study and its extension from 12th birthday onwards. METHODS: The current analysis included PTPs aged ≥12 years old, who remained in the extension for ≥6 months following their 12th birthday. The observation period was defined as the time from 12th birthday to the end of the extension period; all data from this birthday were included whether in the main study or extension phase. The main efficacy variable was annualised bleeding rate (ABR) and the main safety variable was the frequency of inhibitor development. RESULTS: This subgroup analysis comprised 25 patients. Median observation time after 12th birthday was 3.2 years. Median total/joint/spontaneous ABRs in the observation period were 1.7/0.7/0.3, respectively. Safety findings were consistent with those reported for the overall study population; no confirmed FVIII inhibitors or anti-drug antibodies were reported. CONCLUSIONS: Damoctocog alfa pegol is efficacious with a favourable safety profile in adolescents with haemophilia A, supporting its long-term use in children and adolescents.

Assessment of exposure to direct oral anticoagulants in elderly hospitalised patients.

It is unclear whether elderly patients established on direct oral anticoagulants (DOACs) have greater exposure to these drugs, which could subsequently increase their risk of bleeding. We assessed DOAC exposure and factors affecting it in a real-world elderly cohort of patients. For this, 151 medically stable hospital inpatients (76 established on apixaban, 61 on rivaroxaban, 14 on dabigatran) with a median [interquartile range (IQR)] age of 84 (78-89) years were recruited. Patients provided blood samples for measurement of peak and trough plasma DOAC concentrations. There was up to 48-fold and 13-fold variation in trough and peak plasma drug concentrations respectively. A significantly greater proportion of patients on apixaban had peak plasma drug concentrations within the reported ranges compared to those on either rivaroxaban or dabigatran (82·9% vs. 44·3% vs. 64·3% respectively; P < 0·001). A third of the variability in DOAC plasma concentrations was attributed to the influences of DOAC dosage, renal function and gender. To what extent the observed increases in DOAC exposure in the older patients is the cause of their increased risk of bleeding, which could potentially be ameliorated by dosing titration, requires further investigation.

Immune tolerance induction in severe haemophilia A: A UKHCDO inhibitor and paediatric working party consensus update.

INTRODUCTION: In good risk patients (historic inhibitor peak < 200BU), the International Immune Tolerance Study demonstrated equal efficacy to induce tolerance between high (200iu/kg/day) and low dose (50iu/kg ×3 times/week) immune tolerance induction (ITI) regimens. However, the trial stopped early on account of the excessive bleed rate in the low dose ITI arm. METHODS: United Kingdom Haemophilia Centre Doctors' Organization (UKHCDO) Paediatric and Inhibitor working parties considered available ITI data alongside the bi-phenotypic antibody emicizumab (Hemlibra®) efficacy and safety data to develop a consensus guideline for the future UK ITI guideline. RESULTS: This revision of UKHCDO ITI guidance incorporates the recommendation to use emicizumab as a prophylaxis haemostatic agent to reduce bleeding rates and to facilitate low dose and reduced frequency of FVIII CFC for ITI in the majority of children. CONCLUSION: This consensus protocol will facilitate future evaluation of ITI outcomes in the evolving landscape of haemophilia therapeutics and ITI strategies.

PROTECT VIII kids extension study: Long-term safety and efficacy of BAY 94-9027 (damoctocog alfa pegol) in children with severe haemophilia A.

INTRODUCTION: BAY 94-9027 (damoctocog alfa pegol; an extended half-life PEGylated recombinant factor VIII [FVIII]) demonstrated efficacy and safety in previously treated paediatric patients (PTPs) aged <12 years with severe haemophilia A in the PROTECT VIII Kids study (NCT01775618). AIM: To evaluate the long-term safety of BAY 94-9027 in PTPs aged <12 years at enrolment. METHODS: In the PROTECT VIII Kids study, boys <12 years with severe haemophilia A were enrolled in two age cohorts (6-<12 years and <6 years) and treated prophylactically twice weekly, every 5 days or every 7 days, with BAY 94-9027 for ≥50 exposure days (EDs). Patients who had completed ≥50 EDs and ≥6 months in the main study or 12-week safety expansion study were eligible to participate in the extension. Primary safety variable was frequency of inhibitor development; main efficacy variable was annualised bleeding rate (ABR). RESULTS: Of 73 PTPs from the main/expansion studies, 59 (81%) entered the extension phase for a median (range) duration of 5.0 (0.4-5.9) years. Overall, 39 patients completed ≥5 years of treatment. No patients developed FVIII inhibitors/anti-PEG antibodies, and two patients aged <6 years discontinued. Median ABR for total bleeds was 1.5 (<6 years) and 1.9 (6-<12 years). Total ABR improved in the extension vs. the main study. In the last 12 months of treatment, median spontaneous ABR was 0.0 in both age groups. CONCLUSIONS: BAY 94-9027 showed long-term safety and efficacy for the prevention and treatment of bleeds in younger and older paediatric patients with severe haemophilia A.

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.

Elderly people are inherently sensitive to the pharmacological activity of rivaroxaban: implications for DOAC prescribing.

According to both trial and clinical data on direct oral anticoagulants (DOACs) elderly patients are at greatest risk of bleeding. It is unclear whether age intrinsically affects anticoagulation response. To investigate the age-related sensitivity to DOACs, we compared the pharmacological activity of the direct factor Xa inhibitor, rivaroxaban, between young and elderly subjects ex-vivo. 36 fit elderly and 30 fit young subjects [median (IQR) age: 83(75-87) vs 30(26-38) years] provided a blood sample. Clotting parameters were measured in the resultant plasma samples incubated with rivaroxaban (100-500 ng/ml). Parametric, non-parametric tests and regression lines adjusted for rivaroxaban concentration and baseline values were used to compare data. Rivaroxaban produced a greater prolongation of both Prothrombin Time (PT) and modified Prothrombin Time (mPT) (both p < 0.001) in the elderly compared to young subjects (with difference in mean PT increasing from 1.6 to 6.1s and for mPT from 23.5 to 71.1s at 100 ng/ml and 500 ng/ml plasma rivaroxaban concentration, respectively). Factor X and factor II activity was significantly lower in the elderly in the presence of rivaroxaban (p < 0.001 for both). Rivaroxaban prolonged time-based parameters and suppressed the amount of thrombin generation to a significantly greater extent in the elderly compared to young subjects [%change from baseline for Endogenous Thrombin Potential (ETP): - 35.0 ± 4.4 vs - 29.8 ± 7.4 nM*min; p = 0.002]. The use of validated DOAC assays will be of considerable benefit for monitoring elderly patients who, because of their increased sensitivity to rivaroxaban, may require lower doses of the drug for therapeutic anticoagulation.

Safety and efficacy of rivaroxaban in pediatric cerebral venous thrombosis (EINSTEIN-Jr CVT).

Anticoagulant treatment of pediatric cerebral venous thrombosis has not been evaluated in randomized trials. We evaluated the safety and efficacy of rivaroxaban and standard anticoagulants in the predefined subgroup of children with cerebral venous thrombosis (CVT) who participated in the EINSTEIN-Jr trial. Children with CVT were randomized (2:1), after initial heparinization, to treatment with rivaroxaban or standard anticoagulants (continued on heparin or switched to vitamin K antagonist). The main treatment period was 3 months. The primary efficacy outcome, symptomatic recurrent venous thromboembolism (VTE), and principal safety outcome, major or clinically relevant nonmajor bleeding,were centrally evaluated by blinded investigators. Sinus recanalization on repeat brain imaging was a secondary outcome. Statistical analyses were exploratory. In total, 114 children with confirmed CVT were randomized. All children completed the follow-up. None of the 73 rivaroxaban recipients and 1 (2.4%; CVT) of the 41 standard anticoagulant recipients had symptomatic, recurrent VTE after 3 months (absolute difference, 2.4%; 95% confidence interval [CI], -2.6% to 13.5%). Clinically relevant bleeding occurred in 5 (6.8%; all nonmajor and noncerebral) rivaroxaban recipients and in 1 (2.5%; major [subdural] bleeding) standard anticoagulant recipient (absolute difference, 4.4%; 95% CI, -6.7% to 13.4%). Complete or partial sinus recanalization occurred in 18 (25%) and 39 (53%) rivaroxaban recipients and in 6 (15%) and 24 (59%) standard anticoagulant recipients, respectively. In summary, in this substudy of a randomized trial with a limited sample size, children with CVT treated with rivaroxaban or standard anticoagulation had a low risk of recurrent VTE and clinically relevant bleeding. This trial was registered at clinicaltrials.gov as #NCT02234843.

Consensus-based clinical recommendations and research priorities for anticoagulant thromboprophylaxis in children hospitalized for COVID-19-related illness.

BACKGROUND: Observational studies indicate that children hospitalized with COVID-19-related illness, like adults, are at increased risk for venous thromboembolism (VTE). A multicenter phase 2 clinical trial of anticoagulant thromboprophylaxis in children hospitalized with COVID-19-related illness has recently been initiated in the United States. To date, there remains a paucity of high-quality evidence to inform clinical practice world-wide. Therefore, the objective of this scientific statement is to provide consensus-based recommendations on the use of anticoagulant thromboprophylaxis in children hospitalized for COVID-19-related illnesses, and to identify priorities for future research. METHODS: We surveyed 20 pediatric hematologists and pediatric critical care physicians from several continents who were identified by Pediatric/Neonatal Hemostasis and Thrombosis Subcommittee leadership as having experience and expertise in the use of anticoagulant thromboprophylaxis and/or the management of COVID-19-related illness in children. A comprehensive review of the literature on COVID-19 in children was also performed. RESULTS: Response rate was 90%. Based on consensus of expert opinions, we suggest the administration of low-dose low molecular weight heparin subcutaneously twice-daily as anticoagulant thromboprophylaxis (in the absence of contraindications, and in combination with mechanical thromboprophylaxis with sequential compression devices, where feasible) in children hospitalized for COVID-19-related illness (including the multisystem inflammatory syndrome in children [MIS-C]) who have markedly elevated D-dimer levels or superimposed clinical risk factors for hospitalassociated VTE. For children who are clinically unstable or have severe renal impairment, we suggest the use of unfractionated heparin by continuous intravenous infusion as anticoagulant thromboprophylaxis. In addition, continued efforts to characterize VTE risk and risk factors in children with COVID-19, as well as to evaluate the safety and efficacy of anticoagulant thromboprophylaxis strategies in children hospitalized with COVID-19-related illness (including MIS-C) via cooperative multicenter trials, were identified among several key priorities for future research. CONCLUSION: These consensus-based recommendations on the use of anticoagulant thromboprophylaxis in children hospitalized for COVID-19-related illnesses and priorities for future research will be updated as high-quality evidence emerges.

Therapeutic metamorphosis: Findings from a grounded theory study of the impact of low-dose prophylaxis in children living with haemophilia in India.

INTRODUCTION: The clinical benefits of administering low-dose prophylaxis in children with haemophilia are well established. Qualitative research describing the impact of prophylaxis on quality of life is comparatively rare in this area. AIM: The aim of this study was to investigate in children the experiences of living and becoming adjusted to haemophilia before prophylaxis, by collecting information directly from children and their parents or guardians. A further goal was to evaluate whether and how the use of low-dose prophylaxis impacts the disease experience. METHODS: A grounded theory design according to Strauss and Corbin was chosen for this study. The study was conducted in the Haemophilia Treatment Centre at Aluva, Kerala, India and involved nineteen participants (children, mothers, father and grandmothers) who were selected by theoretical sampling. Data were collected through audiotaped interviews, which included demographic and semi-structured interview questions. Data were coded and evolved into concepts and categories that lead to the emergence of theory. RESULTS: The study resulted in the construction of 'Theory of Therapeutic Metamorphosis'. It comprised two stages: stage of bondage (enduring hardships), experienced during the absence of prophylaxis or on-demand treatment and stage of freedom (deliverance/reductions, energized life/improvements and behaviour to seek prophylaxis) experienced during low-dose prophylaxis. CONCLUSION: This study illustrates the challenges faced by children with haemophilia and their families and the positive impact of low-dose prophylaxis. Further prospective research studies are required to add to the growing knowledge in this area.

Guidelines on the use of prophylactic factor replacement for children and adults with Haemophilia A and B

The writing group produced the draft guideline, which was subsequently revised by consensus. Review of the manuscript was performed by the BSH Guidelines Committee Haemostasis and Thrombosis Taskforce, the BSH Guidelines Committee and the Haemostasis and Thrombosis sounding board of the BSH. It was also on the members section of the BSH website for comment. It has also been reviewed by members of the United Kingdom Haemophilia Centre Doctors' Organisation (UKHCDO) Advisory Board, Haemophilia Nurses Association (HNA), Haemophilia Chartered Physiotherapists Association (HCPA); these organisations do not necessarily approve or endorse the contents.

PROTECT VIII Kids: BAY 94-9027 (PEGylated Recombinant Factor VIII) safety and efficacy in previously treated children with severe haemophilia A.

INTRODUCTION: BAY 94-9027, a site-specifically PEGylated, B-domain-deleted recombinant factor VIII (FVIII) with extended half-life, demonstrated efficacy for bleed prevention and treatment in previously treated adolescents and adults with severe haemophilia A. AIM: To assess BAY 94-9027 in children with severe haemophilia A. METHODS: In the two-part PROTECT VIII Kids study, boys <12 years with <1% FVIII and >50 exposure days (EDs) to FVIII were enrolled in two cohorts (<6 years; 6-<12 years) and treated with BAY 94-9027 prophylaxis twice-weekly, every 5 days, or every 7 days at physician discretion for ≥50 EDs (Part 1) or twice-weekly for 12-weeks (Part 2). Annualized bleeding rate (ABR) was a primary efficacy endpoint; FVIII inhibitor development was the primary safety variable. RESULTS: At study completion, 25 patients had been treated twice-weekly, 28 in the every-5-day group, and 8 in the every-7-day group. Median ABR for all bleeds was 2.9 (Part 1) and 2.4 (Part 2) and similar in younger and older patients; median ABR for joint bleeds was 0 for both cohorts. In the last 90 days' treatment, median ABR was 0 for younger and older patients (Part 1). Of 149 reported bleeds, 93% were treated with ≤2 infusions. Twelve patients, the majority <6 years (n = 11), discontinued due to apparent loss of efficacy or hypersensitivity. No FVIII inhibitors developed. CONCLUSIONS: In PROTECT VIII Kids, which allowed tailoring of prophylaxis to individual clinical response, BAY 94-9027 was efficacious for bleed prevention and treatment in previously treated children with severe haemophilia A.

Epidemiology and outcomes of clinically unsuspected venous thromboembolism in children: A systematic review.

BACKGROUND: Clinically unsuspected venous thromboembolic events (uVTE) detected during routine imaging pose a management challenge due to limited knowledge about their clinical significance. Unsuspected VTE are often referred as "asymptomatic," "incidental," or "clinically silent/occult" VTE. OBJECTIVE: To understand the epidemiology, management, and outcomes of uVTE in children. METHODS: A systematic review was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The search criteria included controlled vocabulary and keywords for VTE, incidental findings, and children (ages ≤ 21 years). RESULTS: Among 10 875 articles, 51 studies (8354 children with 758 uVTE) were selected. The studies were heterogeneous, I2 96%; P < .0001. Unsuspected VTE were diagnosed in two settings: first, asymptomatic VTE (aVTE) diagnosed through surveillance imaging for VTE (46 studies; n = 5894; aVTE: 715, pooled frequency: 19%, 95% confidence interval [CI]: 13%-24%); second, incidental VTE (iVTE) diagnosed during imaging performed for indications without primary suspicion for VTE (6 studies; n = 2460; iVTE: 43). The majority (94%) of aVTE were associated with central venous lines (CVL). Non-CVL settings included post-spinal surgery, post-splenectomy, trauma, nephrotic syndrome, and newborns. In general, aVTE were reported to have a benign clinical course, were mostly transient, and resolved without intervention and with few immediate or long-term functional complications. Incidental VTE were primarily detected in children with cancer and ranged from tumor-associated thrombi to pulmonary embolism (PE) with insufficient evidence to draw meaningful conclusions about their management. CONCLUSION: Clinically uVTE were predominantly diagnosed with CVL and their outcomes were generally favorable implying limited benefit of routine surveillance and thromboprophylaxis. Prospective research is needed to clarify the optimal management of iVTE.