Identifying Children with HEreditary Coagulation disorders (iCHEC): a protocol for a prospective cohort study

INTRODUCTION

It is challenging to obtain a reliable bleeding history in children who are referred for a suspected inherited bleeding disorder. Bleeding symptoms may be subtle as children face fewer haemostatic challenges compared with adults. In order to standardise bleeding histories, questionnaires have been developed, called bleeding assessment tools (BATs). Although it has been shown that high bleeding scores are associated with the presence of a mucocutaneous bleeding disorder, these BATs lack sensitivity, efficiency and flexibility in the paediatric setting. We developed a new BAT (the iCHEC (identifying Children with HEreditary Coagulation disorders) BAT) to improve on these characteristics. We aim to evaluate the diagnostic accuracy of the iCHEC BAT as a screening tool for children who are suspected for having a bleeding disorder.

METHODS AND ANALYSIS

This is a prospective cohort study. Children (age 0-18 years) suspected for a bleeding disorder who present at tertiary haematology clinics, and/or their parents/guardians, will be asked to complete the iCHEC BAT. Sensitivity was increased by inclusion of paediatric-specific bleeding symptoms and novel qualitative questions per bleeding symptom. Efficiency was improved by developing a self-administered (online) version of the questionnaire. Flexibility for changes in the bleeding phenotype of developing children was improved by including questions that define when the bleeding symptoms occurred in the past. The diagnostic accuracy of the specific bleeding items will be evaluated by receiver operator characteristic curves, using classification based on the results from laboratory assessment as the reference standard. Analysis of the discriminative power of individual bleeding symptoms will be assessed.

ETHICS AND DISSEMINATION

The study has been approved by the medical ethics committees of all participating centres in the Netherlands, Canada and the UK. All paediatric subjects and/or their parents/guardians will provide written informed consent. Study results will be submitted for publication in peer-reviewed journals.

Severity and Features of Epistaxis in Children with a Mucocutaneous Bleeding Disorder

OBJECTIVE

To use standardized bleeding questionnaires to compare the severity and patterns of epistaxis in children with a mucocutaneous bleeding disorder and control children.

STUDY DESIGN

The epistaxis sections of the Pediatric Bleeding Questionnaire (PBQ) administered to pediatric patients with von Willebrand disease or a platelet function disorder and healthy control children were reviewed. Scores and features of epistaxis (frequency, duration, onset, site, seasonal correlation, and need for medical/surgical intervention) were recorded. A PBQ epistaxis score ≥2 was defined as clinically significant. The Katsanis epistaxis scoring system was administered to eligible patients, ie, with ≥5 episodes of epistaxis per year.

RESULTS

PBQ epistaxis scores were obtained for 66 patients, median age 12 years (range 0.6-18.3 years), and 56 control children. The median PBQ epistaxis score in patients was 2 vs 0 in control children (P <.0001). All of the features of epistaxis, except spontaneous onset, occurred in a significantly greater proportion of patients than control children with epistaxis. A total of 50% of the patients were graded as having severe epistaxis by the Katsanis epistaxis scoring system, and 30 of these (91%) had a clinically significant PBQ epistaxis score.

CONCLUSION

Standardized bleeding questionnaires are useful in the assessment of epistaxis severity and pattern and may help to distinguish children with and without a mucocutaneous bleeding disorder.

Evaluation of the age-dependent dosing recommendations for the administration of daily tinzaparin in children with thrombosis

Essentials The once-daily dosing of tinzaparin provides an advantage over other low molecular weight heparins. The recommended age-dependent doses of tinzaparin in children have not previously been validated. Once-daily administration of tinzaparin is a safe and effective treatment of childhood thrombosis. Recommended doses are appropriate but monitoring may be required due to inter-individual variation.

SUMMARY

Background The recommended starting doses of tinzaparin for the treatment of thrombosis in children have not previously been validated. There are few data to support the efficacy and safety of once-daily tinzaparin dosing in children with thrombosis. Objectives To investigate the use of tinzaparin for the treatment of childhood thrombosis, and to evaluate the age-dependent dosing recommendations and define outcomes in terms of efficacy and safety. Methods This was a retrospective cohort study of children aged 0 to < 16 years treated for thrombosis at a large teaching hospital in the UK between 2008 and 2015. Medical records were reviewed to evaluate tinzaparin dosing, anti-activated factor X (FXa) levels, and patient outcomes. Results Seventy-nine children were identified as having received tinzaparin. Dosing information was available for 57. Younger children required higher doses to reach a therapeutic level. The therapeutic dose requirement varied within age groups, supporting the use of anti-FXa monitoring. Over a median follow-up of 35 months, there were 13 (16%) bleeding episodes (two major; seven clinically relevant but non-major; and four minor). There were two (3%) recurrent episodes of thrombosis. Children were treated for a median duration of 3 months, and the majority (86%) remained on tinzaparin for the duration of their anticoagulant therapy. Conclusion Once-daily tinzaparin is a safe and effective treatment for childhood thrombosis, with rates of recurrence and bleeding similar to those for other anticoagulants used in children. The recommended starting doses are appropriate, but anti-FXa monitoring may be required, owing to interindividual variability in the therapeutic dose requirement.

Pulmonary embolism and in situ pulmonary artery thrombosis in paediatrics

Data on paediatric pulmonary embolism (PE) are scarce. We sought to systematically review the current literature on childhood PE and conducted a search on paediatric PE via PubMed (1946–2013) and Embase (1980–2013). There was significant heterogeneity in reported data. Two patterns were noted: classic thromboembolic PE (TE-PE) and in situ pulmonary artery thrombosis (ISPAT). Mean age of presentation for TE-PE was 14.86 years, and 51% of cases were males. The commonest method for diagnosis of TE-PE was contrast CT with angiography (74% of patients). The diagnosis of TE-PE was often delayed. Although 85% of children with TE-PE had an elevated D-dimer at presentation, it was non-discriminatory for the diagnosis. In paediatric TE-PE, the prevalence of central venous catheters was 23%, immobilisation 38%, systemic infection 31% and obesity 13%, elevated Factor VIII or von Willebrand factor levels 27%, Protein C deficiency 17%, Factor V Leiden 14% and Protein S deficiency 7%. In patients with TE-PE, pharmacologic thrombolysis was used in 29%; unfractionated heparin was the most common initial anticoagulant treatment in 64% and low-molecular-weight heparins the most common follow-up treatment in 83%. Duration of anticoagulant therapy was variable and death was reported in 26% of TE-PE patients. In contrast to TE-PE, patients with ISPAT were not investigated systematically for presence of thrombophilia, had more surgical interventions as the initial management and were often treated with anti-platelet medications. This review summarises important data and identifies gaps in the knowledge of paediatric PE, which may help to design future studies.

Venous Thromboembolism in Children: Is It Preventable?

The incidence of venous thromboembolism (VTE) in children is increasing. Hospitalized infants and adolescents are at highest risk, and most individuals who have VTE have multiple thrombotic risk factors. The presence of a central venous catheter (CVC) is the most frequent risk factor for childhood thrombosis. Childhood VTE has significant consequences in relation to the thrombotic event and the anticoagulant therapy used for its treatment. Identification of the most prevalent risk factors for VTE, particularly among adolescents, has moved the focus toward prevention of thrombosis. Risk assessment models have been developed to identify individuals who are at higher risk with a view to employing preventative strategies such as mechanical and chemical thromboprophylaxis (TP). There is currently little evidence to support the efficacy of such strategies for preventing either CVC-associated thrombosis or thrombosis at other sites. In addition, there are concerns about adverse consequences of mechanical and chemical TP in a population where the overall incidence of VTE remains low.

Characterizing variability in warfarin dose requirements in children using modelling and simulation

Aims

Although genetic, clinical and demographic factors have been shown to explain approximately half of the inter-individual variability in warfarin dose requirement in adults, less is known about causes of dose variability in children. This study aimed to identify and quantify major genetic, clinical and demographic sources of warfarin dose variability in children using modelling and simulation.

Methods

Clinical, demographic and genetic data from 163 children with a median age of 6.3 years (range 0.06–18.9 years), covering over 183 years of warfarin therapy and 6445 INR observations were used to update and optimize a published adult pharmacometric warfarin model for use in children.

Results

Genotype effects in children were found to be comparable with what has been reported for adults, with CYP2C9 explaining up to a four-fold difference in dose (CYP2C9 *1/*1 vs. *3/*3) and VKORC1 explaining up to a two-fold difference in dose (VKORC1 G/G vs. A/A), respectively. The relationship between bodyweight and warfarin dose was non-linear, with a three-fold difference in dose for a four-fold difference in bodyweight. In addition, age, baseline and target INR, and time since initiation of therapy, but not CYP4F2 genotype, had a significant impact on typical warfarin dose requirements in children.

Conclusions

The updated model provides quantitative estimates of major clinical, demographic and genetic factors impacting on warfarin dose variability in children. With this new knowledge more individualized dosing regimens can be developed and prospectively evaluated in the pursuit of improving both efficacy and safety of warfarin therapy in children.

Quantitation of bleeding symptoms in children with von Willebrand disease: use of a standardized pediatric bleeding questionnaire

SUMMARY BACKGROUND

Excessive bruising and mucocutaneous bleeding are frequent presenting symptoms in childhood. A detailed bleeding history can distinguish children who may have an inherited bleeding disorder from those who are normal. There is a lack of standardization of such history taking in pediatric practise.

OBJECTIVES

To assess the performance of a Pediatric Bleeding Questionnaire (PBQ), an adaptation of a standardized adult bleeding questionnaire and score that includes pediatric-specific bleeding symptoms, in a cohort of children with von Willebrand disease (VWD).

PATIENTS/METHODS

Bleeding scores were determined by interview, for children with a previous diagnosis of VWD and a control group of unaffected siblings.

RESULTS

Bleeding scores were obtained for 100 children with VWD, median age 10.9 years (range, 0.8-17.8 years), and 21 unaffected siblings. Median bleeding score in children with VWD was 7.0 (range, 0-29) and in the control group was 0 (range, -1-2). Bleeding score varied within and between each VWD type: definite type 1, n = 40, median, 9.0 (range, 2-18); possible type 1, n = 38, median, 2.0 (0-15); type 2, n = 6, median, 14.0 (3-17); and type 3, n = 16, median, 12.0 (4-29). Bleeding scores in affected children correlated with age (Spearman's correlation coefficient, 0.35; P = 0.0004). The most frequent clinically significant bleeding symptoms were surgical bleeding, bleeding after tooth extraction and menorrhagia. Post-circumcision bleeding, cephalohematoma, macroscopic hematuria and umbilical stump bleeding were clinically significant in 32% (of circumcised males), 4%, 4% and 3% of children, respectively.

CONCLUSIONS

The PBQ provides a standardized quantitation of bleeding severity in children with VWD.

Clinical probability score and D-dimer estimation lack utility in the diagnosis of childhood pulmonary embolism

BACKGROUND

Childhood pulmonary embolism (PE) causes significant mortality and evidence suggests that it is under-diagnosed. Clinical probability scores and D-dimer estimation to assess pre-test probability have not been studied in children with suspected PE.

PATIENTS/METHODS

This retrospective cohort study evaluated Wells simplified probability score for PE in 50 children with PE and 25 PE negative control patients, and D-dimer values in 27 PE positive and 12 PE negative children.

RESULTS

PE positive and PE negative groups had similar rates of risk factors for venous thromboembolism (VTE). Wells simplified probability score showed a small difference between PE positive and PE negative children (median score: PE positive, 4.5; PE negative, 4; P = 0.009), children with PE are more likely to obtain a 'PE likely' score (score > 4), P = 0.012. The difference was of slightly greater significance when the Wells score was adjusted to account for pediatric normal ranges for heart rate, P = 0.007, and signs/symptoms of upper limb DVT, P = 0.006. Children with PE were as likely as PE negative patients to have a D-dimer value within the normal range (PE positive, 15%; PE negative, 25%; P = 0.654). A combination of a 'PE unlikely' score and normal D-dimer value occurred in 1/12 (8%) of PE negative children.

CONCLUSIONS

The Wells clinical probability score and D-dimer estimation may lack utility in the determination of pre-test probability of PE in children. Validation of a pediatric clinical probability score, incorporating D-dimer estimation, by prospective study, would be difficult as a result of the rarity of childhood PE.

The use of elastic compression stockings for post-thrombotic syndrome in a child

Post-thrombotic syndrome (PTS) is a potential complication following deep vein thrombosis (DVT) in children. Guidelines for management of PTS in children are non-existent. The absence of guidelines may limit the use of elastic compression stockings (ECS), offered for prevention and treatment of PTS in adults. We report the case of a 6-year-old, who developed PTS following a presumed line-related lower limb DVT, with dramatic improvement in functional status with ECS use. The presented case highlights the subtle nature of symptoms, potential benefits and limitations of ECS use for PTS, and current lack of evidence in children.

Failure of rituximab to induce immune tolerance in a boy with severe haemophilia A and an alloimmune factor VIII antibody: a case report and review of the literature

We report the use of rituximab (MabThera); Roche Grenzach-Wyhlen, Germany) in a 6-year-old boy with severe haemophilia A and a high titre alloimmune factor VIII (FVIII) antibody, which had failed to respond to standard immune tolerance therapy. Rituximab was administered in 4 weekly doses with concurrent high-dose i.v. immunoglobulin (Flebogamma); Grifols, Barcelona, Spain) followed by daily high-dose recombinant FVIII concentrate (Recombinate); Baxter, CA, USA). Despite a fall in CD20 positive cell count to undetectable levels the inhibitor persisted. We discuss the possible reasons for failure of immune tolerance induction and review the literature concerning the use of rituximab for this indication.

Recombinant activated factor VII (rFVIIa/NovoSevenR) in intractable haemorrhage: use of a clinical scoring system to predict outcome

BACKGROUND AND OBJECTIVES

Recombinant activated factor VII (rFVIIa/NovoSeven) has been advocated in the treatment of life-threatening haemorrhage, but appropriate clinical indications remain uncertain. The aim of this study was to detect factors predictive of outcome and to incorporate them into a prognostically significant scoring system.

MATERIALS AND METHODS

Thirty-six patients received rFVIIa for uncontrolled surgical, traumatic or obstetric bleeding in the Northern Region of the UK over a 45-month period. Clinical, laboratory and outcome data were examined. Characteristics of survivor and non-survivor groups were compared. A prognostic scoring system was evaluated retrospectively according to the presence of coagulopathy, renal impairment, hypothermia, greater than 10 units of red cell transfusion, advanced age and obstetric indication, with patients allocated to low, intermediate and high-risk groups.

RESULTS

Clinical response occurred in 26 patients (72%) with a reduction in prothrombin time and blood product requirements. Death occurred in 19 (53%). Four patients (11%) suffered thrombotic events. Survivors were younger than non-survivors and less likely to have coagulopathy, renal impairment or hypothermia at the time of administration. Survivors were more likely to have had an initial clinical response in terms of an immediate reduction in haemorrhage. Non-survivors were transfused a greater number of red cell units prior to administration. Survival varied according to prognostic score; low-risk patients had a survival rate of 85%, intermediate-risk patients had a survival rate of 50% and high-risk patients had a survival rate of 18%.

CONCLUSIONS

FVIIa has a role in the cessation of haemorrhage, but may not improve survival. Use of a clinical scoring system may help to predict outcome.