Determinants of bleeding before and during immune tolerance in 222 boys with severe hemophilia A and inhibitors >5 BU

ABSTRACT

Prevention of bleeding and its consequences is the main goal of hemophilia treatment and determines treatment choices for patients who develop inhibitors. To assess bleeding before and during immune tolerance induction (ITI) and its association with ITI regimen and inhibitor titer, we selected and analyzed data on patients receiving high-titer inhibitors from the international prospective PedNet cohort study. In total, 222 patients with severe hemophilia A and inhibitor titers of >5 Bethesda units (BU) were followed from the first positive to the first negative inhibitor result (median overall follow-up, 1.7 years). Mean annual (joint) bleeding rates (AJBR) and 95% confidence intervals (CIs) were compared according to treatment and inhibitor titer using multivariable negative binomial regression. Before ITI, 115 patients showed an ABR of 6.1 (5.0-7.4) and an AJBR 2.6 (2.1-3.2). Bleeding was independent of inhibitor titer. During ITI, 202 patients had an ABR of 4.4 (3.9-5.1) and an AJBR of 1.7 (1.5-2.0). AJBR during ITI increased with inhibitor titer (hazard ratio [HR] for ≥200 BU vs 5 to 39 BU [4.9; CI, 3.2-7.4]) and decreased with daily ITI infusions (HR, 0.4; CI, 0.3-0.6) or activated prothrombin complex concentrate prophylaxis (HR, 0.4; CI, 0.2-0.8), whereas ITI dose and recombinant activated factor VII prophylaxis did not independently affect bleeding. These data provide evidence for a protective effect of repeated FVIII infusions (ITI) on bleeding in patients who have developed inhibitors; these data should be used to plan ITI and/or serve as a comparator for prophylaxis with nonreplacement therapy.

Notfall-Neuropädiatrie – Der arteriell ischämische Schlaganfall als einer der zeitkritischsten Notfälle bei Kindern und Jugendlichen

Der arteriell ischämische Schlaganfall im Kindes- und Jugendalter gehört zu den zeitkritischsten Notfällen in der Pädiatrie. Dennoch wird er häufig mit einer oft prognostisch relevanten Zeitverzögerung diagnostiziert. Gründe dafür liegen neben der geringen Awareness auch in der zuweilen unspezifischen klinischen Präsentation mit einer herausfordernden Breite kritischer Differenzialdiagnosen sowie in der Fläche noch wenig verzahnter Akutversorgungsstrukturen. Gleichwohl zeigen grundsätzlich die beim Erwachsenen etablierten Revaskularisationsstrategien auch beim Kind ihre möglichen, zum Teil spektakulären Erfolge. Es gilt also, diese nach Möglichkeit auch den betroffenen Kindern zur Verfügung zu stellen, auch wenn hier derzeit ein nicht annähernd vergleichbarer Grad an Evidenz erreicht ist. Postakut ist die ätiologische Aufarbeitung durch die größere Bandbreite zu bedenkender Risikofaktoren besonders komplex, muss aber in der Lage sein, das individuelle Risikoprofil mit Sekundärprophylaxe, Rezidivrisiko und Outcome präzise zu identifizieren. Die Langzeitbetreuung im multiprofessionellen, interdisziplinären Team muss die biopsychosozialen Aspekte des Kindes in seiner jeweiligen Entwicklungsphase berücksichtigen und damit eine bestmögliche Integration des Kindes in sein soziales und schulisches, später berufliches Umfeld realisieren.

Matching-Adjusted Indirect Comparison of Efficacy and Consumption of rVIII-SingleChain Versus Two Recombinant FVIII Products Used for Prophylactic Treatment of Adults/Adolescents with Severe Haemophilia A

Introduction

Given the relatively small number of patients with haemophilia A, head-to-head comparisons between recombinant FVIII (rFVIII) products are difficult to conduct. This study compared the efficacy and consumption of rVIII-SingleChain (lonoctocog alfa, AFSTYLA^®) with rAHF-PFM (octocog alfa, Advate^®) and rFVIIIFc (efmoroctocog alfa, Elocta^®), for the prophylaxis and treatment of bleeding episodes in previously treated adolescents/adults with severe haemophilia A, through a matching-adjusted indirect comparison (MAIC).

Methods

A systematic literature review identified published clinical trials for rAHF-PFM and rFVIIIFc. Individual patient data for rVIII-SingleChain were used to match baseline patient characteristics to those from published trials, using an approach similar to propensity score weighting. After matching, annualized bleeding rates (ABR), percentage of patients with zero bleeds, and rFVIII consumption were compared across trial populations.

Results

Published data were identified from two rAHF-PFM trials and one rFVIIIFc trial. rVIII-SingleChain had similar ABR (risk ratio [RR]: 0.74 [0.16; 3.48]; RR: 1.18 [0.85; 1.65]) and percentage of patients with zero bleeds (odds ratio [OR]: 1.34 [0.56; 3.22]; OR: 0.78 [0.47; 1.31]) versus rAHF-PFM and rFVIIIFc, respectively. Annual rVIII-SingleChain consumption was significantly lower than rAHF-PFM (mean difference: − 1507.66 IU/kg/year [− 2011.71; − 1003.61]) and equivalent to rFVIIIFc (RR: 0.96 [0.62; 1.49]).

Conclusion

Although limited to published information for comparator trials, these results suggest that with an annualized rFVIII consumption comparable to rFVIIIFc, but significantly lower than rAHF-PFM, routine prophylaxis with rVIII-SingleChain is able to maintain a similar ABR and percentage of patients with zero bleeds, attesting to the long-acting nature of rVIII-SingleChain.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01853-0.

It is difficult to directly compare different recombinant FVIII products in head-to-head studies because there are few patients with haemophilia A. This study aimed to indirectly compare the efficacy and consumption of different recombinant FVIII products in the prophylactic treatment of haemophilia A using published clinical data. A proven method for performing indirect comparisons of products is referred to as a matching-adjusted indirect comparison. Using this approach, we were able to compare rVIII-SingleChain with two other recombinant FVIII products (rAHF-PFM and rFVIIIFc). Our results suggest that annual FVIII consumption with rVIII-SingleChain is comparable to rFVIIIFc, but is significantly lower than rAHF-PFM, while maintaining a similar bleeding rate. These results highlight the long-acting nature of the product.

Recanalization strategies in childhood stroke in Germany

Childhood arterial ischemic stroke (CAIS) is a rare event. Diverse etiologies, risk factors, symptoms and stroke mimics hamper obtaining a fast diagnosis and implementing immediate recanalization strategies. Over a period of 3 years (2015–2017), the data of 164 pediatric patients (> 28 days of life-18 years) with a first episode of AIS were submitted to a hospital-based nationwide surveillance system for rare disorders (ESPED). We report a subgroup analysis of patients who have undergone recanalization therapy and compare these data with those of the whole group. Twenty-eight patients (17%) with a median age of 12.2 years (range 3.3–16.9) received recanalization therapy. Hemiparesis, facial weakness and speech disturbance were the main presenting symptoms. The time from onset of symptoms to confirmation of diagnosis was significantly shorter in the intervention group (4.1 h vs. 20.4 h, p ≤ 0.0001). Only in one patient occurred a minor bleed. Cardiac disease as predisposing risk factor was more common in the recanalization group. Recanalization therapies are feasible and increasingly applied in children with AIS. High awareness, timely diagnosis and a large amount of expertise may improve time to treatment and make hyperacute therapy an option for more patients.

Inhibitor incidence in an unselected cohort of previously untreated patients with severe haemophilia B: a PedNet study

The incidence of factor IX (FIX) inhibitors in severe hemophilia B (SHB) is not well defined. Frequencies of 3-5% have been reported but most studies to date have been small, including patients with different severities, and without prospective follow up for inhibitor incidence. The study objective was to investigate the inhibitor incidence in patients with SHB followed up for to 500 exposure days (ED), the frequency of allergic reactions, and the relationship with genotypes. Consecutive previously untreated patients (PUP) with SHB enrolled into the PedNet cohort were included. Detailed data was collected for the first 50 ED, followed by the annual collection of the inhibitor status and allergic re-actions. The presence of inhibitors was defined by at least two consecutive positive samples. Additionally, data on FIX gene mutation was collected. One hundred and fifty-four PUP with SHB were included; 75% were followed up until 75 ED, and 43% until 500 ED. Inhibitors developed in 14 patients (seven high-titer). The median number of ED at inhibitor manifestation was 11 (interquartile range [IQR]: 6.5-36.5). The cumulative inhibitor incidence was 9.3% (95% Confidence Interval [CI]: 4.4-14.1) at 75 ED, and 10.2% (95% CI: 5.1-15.3) at 500 ED. Allergic reactions occurred in four (28.6%) inhibitor patients. Missense mutations were most frequent (46.8%) overall but not associated with inhibitors. Nonsense mutations and deletions with large structural changes comprised all mutations among inhibitor patients and were associated with an inhibitor risk of 26.9% and 33.3%, respectively. In an unselected, well-defined cohort of PUP with SHB, the cumulative inhibitor incidence was 10.2% at 500 ED. Nonsense mutations and large deletions were strongly associated with the risk of inhibitor development. The ‘PedNet Registry’ is registered at clinicaltrials.gov; identifier: NCT02979119.

Optimizing the management of patients with haemophilia A and inhibitors in the era of emicizumab: Recommendations from a German expert panel

Standard treatment of haemophilia A is based on replacing the missing coagulation factor VIII (FVIII) to treat and prevent bleeding episodes. The most challenging complication of FVIII therapy is the development of neutralizing antibodies (inhibitors) that can render treatment ineffective. Eradication of the inhibitor through immune tolerance induction (ITI) remains the most effective strategy for managing these patients. Bypassing agents can be used to help restore haemostasis in inhibitor patients. Several novel agents have recently been developed, such as the FVIII mimetic agent emicizumab, which has been effective in reducing the annualized bleeding rate in haemophilia A patients with inhibitors. When coadministered with repetitive high doses of activated prothrombin complex concentrate (ie >100 U/kg/d for ≥24 hours), emicizumab was associated with thrombotic microangiopathy and thrombosis events. As a consequence the United Kingdom Haemophilia Centres Doctors' Organisation (UKHCDO) issued the first guidance on the treatment of bleeding episodes in patients receiving emicizumab. To build on and extend this work, a panel of German haemophilia specialists met to discuss the UK guidance, review current evidence and provide additional guidance for German healthcare professionals on how to optimize the management of patients with haemophilia A receiving emicizumab. Recommendations are provided on the use of bypassing and other agents to manage breakthrough bleeding, ITI in the emicizumab era, haemostatic support during surgery and issues relating to laboratory monitoring.

Practical Guidance of the GTH Haemophilia Board on the Use of Emicizumab in Patients with Haemophilia A

Emicizumab has been approved for bleeding prophylaxis in patients with haemophilia A (PWHAs) with or without inhibitors. Because of substantial differences between factor VIII (FVIII) and Emicizumab, the 'Ständige Kommission Hämophilie' of the German, Austrian, Swiss Society for Thrombosis and Haemostasis Research (GTH) established a practical guidance for the use of Emicizumab in PWHAs. A systematic literature research was conducted in PubMed. Based on this and on personal experience, this practical guidance has been developed. Each single statement has been discussed among members of the 'Ständige Kommission Hämophilie' and revised accordingly. The final set of recommendations has been approved by all authors analogous to the Delphi method. This practical guidance is provided for physicians treating PWHAs with regard to general aspects, patient education, bleeding treatment, surgery, use of Emicizumab in previously untreated patients (PUPs), patients with newly diagnosed inhibitors and elderly patients. Patients should be treated in expert centres and adequate laboratory tests to monitor Emicizumab levels, FVIII replacement and inhibitors should be available. Early experience of immune tolerance induction protocols integrating Emicizumab is reviewed, and the limited experience in PUPs and very young children is described. So far, no thromboembolic complications have been reported with the concomitant use of FVIII or recombinant activated FVII for bleeding treatment or surgery. Activated prothrombin complex concentrate doses of >100 U/kg for >24 hours should be avoided whenever possible because of the high risk of thrombosis and/or thrombotic microangiopathy. In conclusion, this study is designed to support haemophilia physicians using Emicizumab in physicians treating hemophilia and using (PWHAs). With further post-marketing experience and trials, regular updates are necessary.

Childhood Arterial Ischaemic Stroke: Clinical Presentation, Risk Factors and Management

Childhood arterial ischaemic stroke (AIS) is a rare, but potentially life-threatening event which requires early diagnosis and adequate treatment. The reported significant time delay to childhood AIS diagnosis may be associated with low awareness, the more nonspecific clinical presentation as well as difficult clinical differentiation to more common "stroke mimics" and a less established "acute care structure" with delayed access to proper neuroimaging. Compared with adult stroke care, experiences with acute reperfusion therapies like thrombolysis and mechanical thrombectomy are promising but limited and not based on clinical trials. The etiological work-up is absolutely essential, as the child's individual risk profile determines acute management, secondary prevention, risk of recurrence and outcome. Follow-up care should be organized in a multidisciplinary setting covering all bio-psycho-social aspects to achieve the best integration of the child into its educational, later professional and social environments.

How Do I Counsel Parents of a Newly Diagnosed Boy with Haemophilia A?

With the recent approval of improved therapeutic options for patients suffering from haemophilia A such as the extended half-life, recombinant factor concentrates, non-factor VIII replacement therapies like Emicizumab and after consideration of the currently running clinical trials investigating even more advanced approaches, counselling of parents of a newly diagnosed boy with haemophilia A has not become less demanding. Parents need to be informed about the pathophysiology, the chronic nature and the potential risks that are commonly associated with this disease and its treatment, depending on disease severity. Above all, the safety and efficacy of the medicinal drug(s) to be used are of utmost importance, given the impact of non-virus-inactivated plasma-derived factor concentrates in the 1980s. As a consequence, the subsequent development and registration of recombinant clotting factors from mammalian, and recently, even human, cell cultures are seen by many as a breakthrough, although, regarding the product-type-dependent development of inhibitors in previously untreated patients, the discussion is still open. Clinical data for the humanised bispecific antibody Emicizumab in paediatric patients below 2 years of age without inhibitors who suffer from severe haemophilia A are currently limited.

Health Care Transition of Adolescents and Young Adults with Haemophilia: the Situation in Germany and the Munich experience

Patients suffering from haemophilia encounter various phases in life, in which individual needs, life situations, and self- and disease perception change rapidly. One of these phases spans from the beginning of puberty until early adulthood, in which individuals gain self-responsibility and reach independence and autonomy. In this challenging time that determines future health, adolescents and young adults need sustainable familiar and professional support. A change in health care team and treatment centre may expose adolescent patients to threats but also provides the possible opportunity to be well prepared. While there is emerging evidence that the so-called health care transition programmes are effective in maintaining quality of care in other disease areas, transition programmes for patients with haemophilia are still rare in Germany, and the evidence is limited. We describe the situation in Germany, discuss our experience in Munich and review some of the available guidance; we conclude that transition programmes should become a standard of care in haemophilia.

Prevalence of Obesity in Young Patients with Severe Haemophilia and Its Potential Impact on Factor VIII Consumption in Germany

Similar to the general population, overweight and obesity have increasingly become a medical and economic burden also in patients with haemophilia in industrialized nations. In this study in seven German haemophilia centres, we identified a prevalence of overweight and obesity of 25.2% among 254 young patients <30 years (median: 13 years; range: 0–30 years) with severe haemophilia A and without a history of inhibitors. The median FVIII dosage based on bodyweight was significantly higher in normal weight compared with overweight or obese patients (96.9 vs. 72.9 IU/kg/week, respectively; p < 0.0001). This suggests that an individualized dosing regime which might be based on FVIII pharmacokinetics, physical activity and pre-existing haemophilic arthropathy is applied rather than dosing by bodyweight only. The bleeding rates observed in obese (median: 1; range: 0–17) versus normal weight patients (median: 2; range: 0–28) did not differ significantly (p = 0.057). Lower bleeding rates might be due to reduced activity or expected higher FVIII plasma levels in overweight patients. Due to the increasing prevalence of overweight/obesity in patients with haemophilia an interdisciplinary approach for individualized haemophilia treatment and weight loss programmes might be helpful for optimal and economical treatment for this group of patients.

Impact of Adopting Population Pharmacokinetics for Tailoring Prophylaxis in Haemophilia A Patients: A Historically Controlled Observational Study

BACKGROUND

 Performing individual pharmacokinetics (PK) studies in clinical practice can be simplified by adopting population PK-based profiling on limited post-infusion samples. The objective of this study was to assess the impact of population PK in tailoring prophylaxis in patients with haemophilia A.

PATIENTS AND METHODS

 Individual weekly treatment plans were developed considering predicted plasma factor activity levels and patients' lifestyle. Patients were trained using a visual traffic-light scheme to help modulate their level of physical activity with respect to factor infusions timing. Annualized joint bleeding rate (ABJR), haemophilia-specific quality of life questionnaire for adults (Haemo-QoL-A) and factor utilization were measured for 12 months before and after tailoring, compared within patients and analysed separately for those previously on prophylaxis (P), situational prophylaxis (SP) or on-demand (OD).

RESULTS

 Sixteen patients previously on P, 10 on SP and 10 on OD were enrolled in the study. The median (lower, upper quartile) ABJR changed from 2.0 (0, 4.0) to 0 (0, 1.6) for P (p = 0.003), from 2.0 (2.0, 13.6) to 3.0 (1.4, 7.2) for SP (p = 0.183) and from 16.0 (13.0, 25.0) to 2.3 (0, 5.0) for OD (p = 0.003). The Haemo-QoL-A total score improved for 58% of P, 50% of SP and 29% of OD patients. Factor utilization (IU/kg/patient/year) increased by 2,400 (121; 2,586) for P, 1,052 (308; 1,578) for SP and 2,086 (1,498; 2,576) for OD. One of 138 measurements demonstrated a factor activity level below the critical threshold of 0.03 IU/mL while the predicted level was above the threshold.

CONCLUSION

 Implementing tailored prophylaxis using a Bayesian forecasting approach in a routine clinical practice setting may improve haemophilia clinical outcomes.

Symptom patterns in childhood arterial ischemic stroke: Analysis of a population-based study in Germany

HINTERGRUND

 Die zeitliche Verzögerung zwischen Symptombeginn und Diagnose ist eine Herausforderung in der Behandlung von Kindern mit arteriell ischämischem Schlaganfall. Frühere Studien zur klinischen Präsentation beschäftigten sich v. a. mit kumulativen Symptomen.

ZIELSETZUNG

 Ziel dieser Studie ist es, mögliche Symptommuster aufzuzeigen.

METHODEN

 In einer aktiven Beobachtungsstudie zwischen 01/2015 und 12/2016 (ESPED-Studie) wurden Kinder mit Erstdiagnose eines arteriell ischämischen Schlaganfalls eingeschlossen. Isoliert auftretende Erstsymptome wurden verschiedenen Symptomkombinationen gegenübergestellt. Zudem wurde untersucht, inwieweit ein als "akut" oder "progredient" klassifiziertes Auftreten der Symptome Rückschlüsse auf die zugrundeliegende Ätiologie erlaubt.

ERGEBNISSE

 Es wurden 99 Kinder in die Studie eingeschlossen. Unabhängig vom Alter traten überwiegend fokale Symptome auf (86%). Krampfanfälle als Initialsymptom wurden insbesondere bei Säuglingen beschrieben (67%), wohin-gegen diffuse, unspezifische Symptome vor allem bei Vorschulkindern (38%) und älteren Kindern (59%) auftraten. Isoliert traten fokale Symptome bei 37 Kindern auf, 48 Kinder zeigten zusätzlich unspezifische Symptome, darunter auch 9 Kinder mit Krampfanfällen. Isolierte unspezifische Symptome zeigten sich lediglich bei 7 Kindern, 2 Kinder wurden nur mit Krampfanfällen symptomatisch. Die Akuität des Symptombeginns wurde bei 53/78 als "akut" und bei "25/78 Fällen als "progredient" klassifiziert, lieferte jedoch keinen Hinweis auf die zugrundeliegende Ätiologie.

SCHLUSSFOLGERUNG

 Jedes neue fokal neurologische Defizit sollte unabhängig vom Auftreten (isoliert oder kombiniert, akut oder progredient) an einen kindlichen Schlaganfall denken lassen.

BACKGROUND

 Time delay between onset of clinical symptoms and diagnosis is a challenge in childhood arterial ischemic stroke. Most previous studies reported cumulative symptoms.

OBJECTIVE

 We attempted to identify typical symptom patterns and assessed their emergence in childhood stroke.

METHODS

 Prospective active surveillance in ESPED, a hospital based Pediatric Surveillance Unit for rare diseases in Germany, between January 2015 and December 2016. Case definition: first diagnosis of a radiologically confirmed arterial ischemic stroke. Symptom patterns were identified as occurring in isolation or in combination. We distinguished acute vs. progressive onset. We ascertained risk factors to identify the possible etiology.

RESULTS

 99 children with childhood arterial ischemic stroke were reported. Focal symptoms were the predominant presenting feature (86%), independent of age. Seizures were more often seen in infants < 1 year (67%), whereas diffuse symptoms were more present in pre-school children (38%) and older children (59%). 37 children had focal features alone and 48 additional non-specific features, including 9 with seizures. Isolated non-specific features accounted for 7 cases, and 2 children had (focal) seizures as the only symptom. In 77% of all cases at least one risk factor was identified. The emergence of symptoms was acute in 53/78 cases and progressive in 25/78 cases. The pattern of emergence was unrelated to the underlying etiology.

CONCLUSIONS

 Any new focal neurological deficit in isolation, or associated with seizures or further non-specific symptoms should alert to childhood stroke.

Validation of the Haemophilia & Exercise Project-Test-Questionnaire (HEP-Test-Q)-An instrument for the assessment of subjective physical functioning in children with haemophilia

INTRODUCTION

Contemporary haemophilia management recommends sport and physical activity in children with haemophilia. Assessment of subjective physical functioning requires standardized and validated instruments.

AIMS

To adapt and psychometrically test the adult Haemophilia & Exercise Project-Test-Questionnaire (HEP-Test-Q) for children (aged 6-17 years).

METHODS

In discussion rounds with children, single items of the adult HEP-Test-Q were reformulated to make them understandable without changing the item concept. The validation of the child-adapted version in children with haemophilia (n = 228) included pre-testing with feasibility testing, cognitive interviewing (n = 34), pilot-testing of the revised version in the EIS Study (n = 67) and field-testing in the SO-FIT Study (n = 127).

RESULTS

Pre-testing revealed a completion time of 8.2 ± 4.1 minutes and children liked the instrument. Cognitive interviews demonstrated that most items were easy to understand; 9 items were reformulated. Pilot-testing demonstrated good psychometric characteristics in terms of reliability (α = .94 Total Score) and validity. Convergent validity testing showed moderate correlations with the Haemo-QoL (r = -.491), but low correlations with the Petrini Score (r = -.293). Known groups' validity revealed significant differences in clinical subgroups; chronic pain (P < .002) and target joints (P < .021). Field-testing confirmed psychometric characteristics; Cronbach's alpha ranged from α = .80 ("endurance") to α = .94 (Total Score). The child-adapted HEP-Test-Q showed moderate correlations with the PedHAL (r = .634, P < .0001) and the Haemo-QoL SF (r = -.575, P < .0001). Known groups' validity testing proved that the HEP-Test-Q could discriminate between clinical subgroups.

CONCLUSION

The child-adapted HEP-Test-Q is a short, practical and acceptable instrument for the assessment of subjective physical functioning. Outcomes can be compared to adults because item concepts are identical to the adult version.

Risk factors in childhood arterial ischaemic stroke: Findings from a population-based study in Germany

OBJECTIVE

Acute treatment of childhood arterial ischaemic stroke and prevention strategies for recurrent stroke episodes depend strongly on each child's individual risk profile. The aim of this study is to characterize risk factors for childhood stroke, their occurrence in isolation or combination, and to identify possible common risk factor patterns.

METHODS

This population-based study was conducted via ESPED, a surveillance unit for rare paediatric diseases in Germany. Children aged >28days and <18 years with an acute arterial ischaemic stroke occurring between January 2015 and December 2016 were included.

RESULTS

Among 99 reported children with arterial ischaemic stroke, 56 children were male. Male predominance was significant in adolescents from 12 years old onward. Arterial ischaemic stroke was more common in very young children <2 years of age and in adolescence. No risk factor was identified in 27 children. Hypercoagulable states (29%), cardiac disorders (24%), and arteriopathies (21%) were the most common risk factors. Some risk factor categories were more likely to be identified in isolation (i.e. cardiac disorders, prothrombotic abnormalities and chronic head and neck disorders) than others. The number of risk factors (n = 0-4) per patient and risk factor categories did not differ by age.

CONCLUSION

Although we could not identify common patterns of risk factor combinations, several risk factors occurred more likely in isolation than others. Further research should focus on the impact of isolated presumed childhood stroke risk factors like certain prothrombotic abnormalities, migraine or a patent foramen ovale. With regard to different age groups, stroke mechanisms in male adolescents require particular attention.

Prospects for research in haemophilia with real-world data-An analysis of German registry and secondary data

INTRODUCTION AND AIM

Open questions in haemophilia, such as effectiveness of innovative therapies, clinical and patient-reported outcomes (PROs), epidemiology and cost, await answers. The aim was to identify data attributes required and investigate the availability, appropriateness and accessibility of real-world data (RWD) from German registries and secondary databases to answer the aforementioned questions.

METHODS

Systematic searches were conducted in BIOSIS, EMBASE and MEDLINE to identify non-commercial secondary healthcare databases and registries of patients with haemophilia (PWH). Inclusion of German patients, type of patients, data elements-stratified by use in epidemiology, safety, outcomes and health economics research-and accessibility were investigated by desk research.

RESULTS

Screening of 676 hits, identification of four registries [national PWH (DHR), national/international paediatric (GEPARD, PEDNET), international safety monitoring (EUHASS)] and seven national secondary databases. Access was limited to participants in three registries and to employees in one secondary database. One registry asks for PROs. Limitations of secondary databases originate from the ICD-coding system (missing: severity of haemophilia, presence of inhibitory antibodies), data protection laws and need to monitor reliability.

CONCLUSION

Rigorous observational analysis of German haemophilia RWD shows that there is potential to supplement current knowledge and begin to address selected policy goals. To improve the value of existing RWD, the following efforts are proposed: ethical, legal and methodological discussions on data linkage across different sources, formulation of transparent governance rules for data access, redefinition of the ICD-coding, standardized collection of outcome data and implementation of incentives for treatment centres to improve data collection.

Infrared Thermography as a Non-Invasive Tool to Explore Differences in the Musculoskeletal System of Children with Hemophilia Compared to an Age-Matched Healthy Group

Recurrent joint bleeds and silent bleeds are the most common clinical feature in patients with hemophilia. Every bleed causes an immediate inflammatory response and is the leading cause of chronic crippling arthropathy. With the help of infrared thermography we wanted to detect early differences between a group of clinical non-symptomatic children with hemophilia (CWH) with no history of clinically detected joint bleeds and a healthy age-matched group of children. This could help to discover early inflammation and help implement early treatment and preventative strategies. It could be demonstrated that infrared thermography is sensitive enough to detect more signs of early inflammatory response in the CWH than in healthy children. It seems to detect more side differences in temperature than clinical examination of silent symptoms detects tender points. Silent symptoms/tender points seem to be combined with early local inflammation. Using such a non-invasive and sensor-based early detection, prevention of overloading and bleeding might be achieved.

Haemostatic testing prior to elective surgery in children? Not always!

In Germany, preoperative coagulation tests are commonly used, based on the belief that these tests should identify patients with an increased bleeding risk. However, published evidence does not longer support this approach for both traditional screening tests and novel techniques of global assessment of haemostasis. Unselected screening yields many false positive results and detects irrelevant disorders. It leads to postponement of surgery, anxiety in parents and patients, and is not cost effective. Even worse, it does not reliably detect relevant bleeding disorders such as the most common coagulopathy, von Willebrand disease. The bleeding history of patients and their relatives is a more effective tool to detect patients at risk. According to international guidelines and a joint statement of different German medical societies, a standardized questionnaire should be mandatory in preoperative screening. A diagnostic pathway should be employed to identify patients in whom specific tests are helpful. Because neither laboratory tests nor questionnaires can infallibly predict or exclude perioperative bleeding, guidelines for the management of these unexpected situations have to be established.

Inhibitor-Immunology-Study

The development of inhibitors is one of the most important complications of replacement therapy in haemophilia, affecting mortality and morbidity. Inhibitor development is based on complex immunological factors. Cytokines and their receptors, T-cell receptors, and the Major Histocompatibility Complex may play important roles in the development of inhibitors. Earlier studies showed non significant associations between HLA class and inhibitor development. Later studies found an increased risk of inhibitor development if there was a combination between certain factor VIII mutations and HLA antigens. We performed HLA typing in 50 patients with haemophilia A in an effort to find associations with inhibitor development. Results: 25 patients had developed an inhibitor (11 low titre, 14 high titre), and 25 never had. In logistic regression analysis, HLA-A 34, DRB1 0405, DRB1 1301 seemed to be involved in inhibitor development and HLA-A 30, B 13, B15, B 57, Cw 12, DQB1 0303, DPB1 0201 protection against inhibitor development. In our patients, the HLA-associations with inhibitor development were different from those in previous publications.

Relevance of a single dose of 270 μg/kg recombinant factor VIIa for the treatment of patients with haemophilia and inhibitors

Recombinant activated factor VII (rFVIIa; Novo Seven®) is, besides other indications, authorised for the treatment of bleeding episodes in patients with hereditary haemophilia A or B and inhibitors. Based on the results of three clinical studies, marketing authorisation was granted for the single dose of 270 μg/kg body weight rFVIIa for the treatment of mild-to-moderate bleeding episodes in patients with haemophilia A or B with inhibitors in March 2007. Thereupon, an expert group analysed the relevance of this additional treatment option for clinical routine. Compared with the repeated application of 90 μg/kg body weight rFVIIa, quality of life may be improved if the single dose of 270 μg/kg body weight rFVIIa reduces the number of injections. The single dose has a benefit for those patients who require several rFVIIa applications or who do not respond adequately to low doses. Moreover, patients with poor venous access or who fear injections or reject them (especially children) may benefit from the single dose. The prescription of 270 μg/kg body weight rFVIIa as a single dose instead of multiple dosing of 90 μg/kg body weight is basically an individual and indication-related decision.

Coagulation testing in the evaluation of suspected child abuse

Every year in Germany nearly 3000 cases of child abuse were reported. When children are presented at emergency units with suspicious injuries and bruises a detailed documentation an evaluation is necessary after emergency treatment. As differential diagnosis inherited or acquired bleeding disorders should be excluded. In addition to a detailed evaluation of personal and family history and a physical evaluation different coagulation test to exclude defects of primary and secondary hemostasis should be performed. Clinician must know the limitations of these tests and keep in mind that an abnormal coagulation test does not exclude child abuse. Coagulation defects may be the consequence of child abuse and neglect or the two conditions may coexist.

Thrombophilia in the young

Venous thromboembolism (VTE) is a rare disease that is being increasingly diagnosed and recognized in paediatrics in the past decade, usually as a secondary complication of primary severe underlying diseases. Apart from acquired thrombophilic risk factors, such as lupus anticoagulants, inherited thrombophilias (IT) have been established as risk factors for venous thromboembolic events in adults. In children with idiopathic VTE and in paediatric populations in which thromboses were associated with underlying medical diseases, IT have been described as additional prothrombotic risk factors. Follow-up data for VTE recurrence in children are available and suggest a recurrence rate of approximately 3% in neonates and 8% in other children. Here we present a review of the impact of IT on early onset of VTE and recurrence in children. Statistically significant associations between the IT traits investigated, e.g. factor V G1691A, factor II G20210A, protein C-, protein S-, antithrombin deficiency, elevated lipoprotein (a), combined IT and VTE onset were reported. In addition, statistically significant associations with recurrent VTE were calculated for protein S-, antithrombin-deficiency, and the factor II variant and combined IT. The absolute risk increase for VTE recurrence associated with IT ranged from 9.8 % for children carrying the factorII variant to 26% and 29% in children with combined IT and protein S-deficiency, respectively. Data obtained gave evidence that the detection of IT is clinically meaningful in children with VTE and underlines the importance of a paediatric thrombophilia screening program. Based on these data treatment algorithms have to be discussed.

Repeated coagulation testing in children

Background Mild bleeding disorders (BD) such as von Willebrand disease (VWD) type I are often difficult to diagnose because of inconclusive laboratory results. Our study examines the diagnostic value of repeated testing.

Patients, methods Prospective study on 200 children. Extensive laboratory testing was done twice and a standardized history was taken.

Results 165 patients completed the study (median age 5.6 years). Main reason for referral was aPTT prolongation (n = 109). The initial diagnosis was upheld in 74/165 (44.8%) children. Of 18 patients rated normal, 8 had to be reclassified as possible VWD later. Ten patients were diagnosed VWD I. In 36 patients possible VWD was found, 13 of these had normal results at the second visit while in 6 VWD became more likely. The main diagnosis was lupus-anticoagulant (n=79), normalizing in 24. A total of 88 children underwent surgery during the study period.

Conclusion Our study shows frequent changes in the diagnosis and highlights the limitations of single laboratory tests in detecting mild BD. Clinical and laboratory abnormalities have to be followed and tests must be repeated in unclear cases. Normal values at one point do not exclude a BD.

Arterial thrombosis in homozygous antithrombin deficiency

Antithrombin (AT), a serin protease inhibitor (serpin) produced in the liver, inhibits mainly thrombin and factor Xa. Antithrombin deficiency (AD) is associated with a higher incidence of thrombosis. Case report: We report a newborn with uncomplicated birth in the 40+5 week of gestation and postnatal appearance of a reticular, livide haematoma on the right upper arm and a tonic clonic epileptic seizure. Clinical examination revealed weak pulses in the A. radialis and ulnaris. MRI scan showed a large thrombus in the A. carotis interna and externa with large cerebral infarction and a thrombus in the A. subclavia. Laboratory work up showed elevated D-dimers and antithrombin levels < 20% (lowest 15%), age-related values for protein C, protein S, plasminogen, and no other inherited thrombophilia. Therapy: We started anticoagulation with unfractionated heparin intravenously (aPTT: 50–60 s) and under suspicion of an AD the substitution of AT (70 U/kg body weight). In course of time we changed anticoagulation to low molecular weight heparin (Anti Xa 0.6–0.8 U/ml) and substitution of 250 E/kg AT every second day. In the molecular work up we found a homozygous missense mutation in exon 2 of SERPINC1 gene (type „Budapest 3”). Molecular analysis showed also heterozygous mutations in both parents and a homozygous mutation in the asymptomatic brother aged three years. At age of six months we changed the anticoagulation to coumadin (INR 2.5–3.5). Anticoagulation with coumadin was also started in the brother. Discussion: Hereditary AD is associated with an increased risk of thrombosis. The homozygous status mainly leads to intrauterine fetal loss or the occurrence of peri- and postnatal thrombosis. Therapy consists in the substitution of AT and a lifelong anticoagulation with vitamin K antagonists also in asymptomatic patients.

Climbing therapy under PK-tailored prophylaxis

Climbing has a low risk of injury and strengthens the entire musculature. Due to its benefits in physical and mental health as well as its high fun factor climbing is an established way of therapy. So far, the usefulness of climbing therapy has not been shown for people with haemophilia (PWH). A crucial requirement for physical activity in PWH is regular prophylaxis. As the patient’s individual pharmacokinetic (PK) response varies significantly, PK-tailored prophylaxis may decrease bleeding frequency. Case report: We describe a man (age 25 years) with severe haemophilia A who took part in an 8.5-month weekly climbing program under PK-tailored prophylaxis. Bleeding frequency, factor consumption, joint health (Haemophilia Joint Health Score, HJHS), quality of life (Haemo-QoL-A) and climbing performance (UIAA scale) were assessed before and after the training. Prior to the study, the patient was on demand treatment. The patient was started on standard prophylaxis for a 2 months period and then observed for 6.5 months under PK-tailored prophylaxis. PK-tailored prophylaxis was targeted to a trough level of 1–3%. For high-impact activities a factor activity >15%, for low-impact activities a factor activity >5% was suggested. Results: Climbing therapy was safe. The bleeding rate decreased from 14 (2012) to 1 (during the study period of 8.5 months). The one bleeding event was due to a missed infusion and was not triggered by physical activity. The elimination half-life using Bayesian statistics was determined to be 16h. Using this half-life for PK-tailored prophylaxis reduced the factor VIII consumption in comparison to standard prophylaxis. Joint health was particularly improved in the categories range of motion and swelling. Quality of life scores stayed at a high level. Climbing performance improved by 1 grade. Conclusio: The combination of PK-tailored prophylaxis with therapeutic climbing improved clinical outcome in this young adult with severe haemophilia. The tailored concept for high- and low-impact activities appeared to be safe.

Postoperative bleeding in paediatric ENT surgery

Bleeding after ear-nose-and throat surgery in children is a serious complication. With the help of the German Surveillance Unit for Rare Paediatric Disorders (Erhebungseinheit für seltene pädiatrische Erkrankungen in Deutschland; ESPED) a two year survey was performed to record the incidence, severity, reasons and treatment of haemorrhages. During the study period, 1069 bleeds were reported from 720 paediatric hospitals and departments of otorhinolaryngology after adenoidectomy and tonsillectomy. 713 reports could be analyzed. Two deaths occurred after adenoidectomy. Although laboratory screening was performed in more than 70% of all cases, bleeding complications were neither foreseeable nor preventable. Inherited coagulopathies were rare and in most cases not detected, neither by laboratory screening nor by taking a history. Since preoperative measures cannot help much to improve the situation, all efforts have to be taken to improve the postoperative period, especially since more than 20% of the hemorrhages occurred during weekends. Guidelines on postoperative care and behaviour should therefore be implemented and parents and patients must be informed on bleeding risks and on what to do in case of emergency. If bleeding occurs, extensive coagulation testing is mandatory.

Haemophilia and thrombophilia

For the study presented here 135 pediatric PUP patients with haemophilia consecutively admitted to German pediatric haemophilia treatment centers were investigated. In addition to factor VIII activity, the factor V (FV) G1691A mutation, the factor II (FII) G20210A variant, methylenetetrahydrofolate reductase (MTHFR) T677T genotype, elevated lipoprotein a (Lp a), antithrombin, protein C, and protein S were investigated. 103 out of 122 HA patients (FVIII activity <1%) were suffering from severe HA. The prevalence of prothrombotic risk factors in children with severe haemophilia A (HA) did not differ from previously reported data: FV GA 5.8%, FII GA 3.9%, MTHFR TT 10%, elevated Lp a 7%, protein C type I deficiency 1.1%. The first symptomatic bleeding leading to diagnosis of severe haemophilia occurred with a median age of 1.6 years (range: 0.5-7.1 years) in children carrying prothrombotic risk factors compared to non-carriers (0.9 years (0.1-4.0; p = 0.01). Two patients presenting with neonatal stroke due to elevated Lp a and the FII GA variant showed haemorrhagic stroke transformation triggered by severe haemophilia. In addition, when haemophilia A was corrected by administration of factor VIII concentrates eight out of 25 children with central lines in place developed catheter-related thrombosis. Conclusion: The data of this multicentre cohort study demonstrate that the clinical phenotype of severe haemophilia A in childhood is clearly influenced by the coinheritance of prothrombotic risk factors.

Symptomatic Onset of Severe Hemophilia A in Childhood is Dependent on the Presence of Prothrombotic Risk Factors

It has been recently suggested that the clinical phenotype of severe hemophilia A (HA) is influenced by co-inheritance with the factor V G1691A mutation. We therefore investigated 124 pediatric PUP patients with hemophilia (A: n = 111) consecutively admitted to German pediatric hemophilia treatment centers. In addition to factor VIII activity, the factor V (FV) G1691A mutation, the prothrombin (PT) G20210A variant, antithrombin, protein C, protein S and anti-thrombin were investigated. 92 out of 111 HA patients (F VIII activity < 1%) were suffering from severe HA. The prevalence of prothrombotic risk factors in children with severe HA was no different from previously reported data: FV G1691A 6.5%, PT G20201A 3.2%, and protein C type I deficiency 1.1%. No deficiency states of antithrombin or protein S were found in this cohort of hemophilic patients. The first symptomatic bleeding leading to diagnosis of severe hemophilia (< 1%) occurred with a median (range) age of 1.6 years (0.5-7.1) in children carrying defects within the protein C pathway or the PT gene mutation compared with non-carriers of prothrombotic risk factors (0.9 years (0.1-4.0; p = 0.01). The cumulative event-free bleeding survival was significantly prolonged in children carrying additionally prothrombotic defects (log-rank/Mantel-Cox: p = 0.0098). In conclusion, data of this multicenter cohort study clearly demonstrate that the first symptomatic bleeding onset in children with severe HA carrying prothrombotic risk factors is significantly later in life than in non-carriers.

Risk Factors for the Progression from Low to High Titres in 260 Children with Severe Haemophilia A and Newly Developed Inhibitors

In children with severe haemophilia A, inhibitors to factor VIII (FVIII) usually develop during the first 50 treatment exposure days and are classified as low or high titre depending on the peak inhibitor titre being greater or less than 5 Bethesda units/mL (BU/mL). Classification of the inhibitor may change with time, as some low-titre inhibitors progress to high titre following re-exposure to FVIII concentrate. The aim of this study was to investigate potential risk factors for such a progression in children with severe haemophilia A and newly diagnosed inhibitors. This study was a follow-up study of the PedNet Registry and included 260 children with severe haemophilia A and inhibitors born between 1990 and 2009 and recruited consecutively from 31 haemophilia centres. Clinical and laboratory data were collected from the date of each child's first positive inhibitor test for at least 3 years. At the time of first positive inhibitor test, 49% (n = 127) had low-titre inhibitors, with 50% of them progressing to high titre and only 25% maintaining low titres. The FVIII gene (F8) mutation type was known in 247 patients (95%), and included 202 (82%) null mutations. The progression to high-titre inhibitors was associated with null F8 mutations (odds ratio [OR]: 2.6; 95% confidence interval [CI]: 1.0–6.5), family history of inhibitors (OR: 7.2; 95% CI: 1.8–28.4) and the use of high-dose immune tolerance induction, defined as ≥100 IU FVIII concentrate/kg/d (OR: 3.9; 95% CI: 1.5–10.0). These results suggest that high-dose immune tolerance induction should be avoided as the initial strategy in patients who develop low-titre FVIII inhibitors.

Increased fasting total homocysteine plasma levels as a risk factor for thromboembolism in children

Elevated total homocysteine (tHcy) concentrations are an inde- pendent risk factor for thromboembolic events in adults. In children with moderate hyperhomocysteinemia data are sparse. Therefore, between 1995 and 2002 we consecutively recruited 163 white pediatric patients with a first symptomatic thromboembolic event and 255 healthy controls (mean age: 6.4 years in patients vs. 6.6 years in controls, range: 3 months to 18 years) and measured fasting tHcy levels. Median tHcy levels in patients were significantly higher (6.6 µmol/l, range 2.9-20.4 µmol/l) than in controls (5.7 µmol/l, 2.0-14.0 µmol/l, p<0.0001). 48 of the 163 patients with thromboembolism (29.5%) versus 26 of the 255 controls (10.2%) had tHcy levels above the age- specific normal 90th percentile (OR 2.9, 95%CI: 1.7-4.8). The odds ratio for children in the highest quintile compared to chil- dren with levels in the lowest quintile was 4.3 (1.6-8.1; highest quintile: median tHcy level 9.6 µmol, range 8.0-20.4), showing a significantly increased risk for thromboembolic disease with even mild hyperhomocysteinemia. We conclude that hyperho- mocysteinemia above the age-specific cut-off values is a risk fac- tor for thromboembolic events in children. Therefore, screen- ing for elevated fasting tHcy levels of patients with thromboem- bolism is recommended to stratify the risk of thromboembo- lism.

Role of protein S deficiency in children with venous thromboembolism

Venous thromboembolism [TE] is a multifactorial disease, and protein S deficiency [PSD] constitutes a major risk factor. In the present study the prevalence of PSD and the clinical presentation at TE onset in a cohort of children is reported. In 367 unselected paediatric patients with TE (age 0.1–18 years) recruited between July 1996 and December 2013, a comprehensive thrombophilia screening was performed along with recording of anamnestic data. Thirty of 367 paediatric patients (8.2 %) derived from 27 families had PSD. Mean age at first TE onset was 14.5 years (range 0.1 to 18). Thrombotic locations were cerebral veins (n=8), calf vein TE (n=3) deep veins (DVT) of the leg (n=12), DVT & pulmonary embolism (n=5) and intra-cardiac veins (n=1) or purpura fulminans (n=1). PSD co-occurred with the factor 5 mutation at rs6025 or the homozygous factor 2 susceptibility variant at rs1799963 in one case each. The Heerlen polymorphism detected in five children presented with milder PSD. In 18 patients (60 %) a concomitant risk factor for TE was identified. A second TE event within primarily healthy siblings occurred in three of 27 PSD families (11.0 %). In this cohort of children with symptomatic TE, the prevalence of PSD adjusted for family status was 7.4 %. Given its clinical implication for patients and family members, thrombophilia testing should be performed and the benefit of medical or educational interventions should be evaluated in this high-risk population.

Effects of primary and secondary prophylaxis on the clinical expression of joint damage in children with severe haemophilia A

Patients with severe haemophilia A (HA) can either be treated by regular FVIII infusions twice or three times per week (prophylaxis), or only in case of bleeding episodes (on-demand). Whereas prophylaxis reduces the number of bleeding episodes and may therefore prevent the development of haemophilic arthropathy, there is still a lot of controversy surrounding recommendations on age and dose at start of prophylactic regimens. The present database study was performed to investigate the role of primary versus secondary prophylaxis in HA children. The outcome variable was imaging-proven haemophilic joint damage. Forty-two children were initially treated with primary prophylaxis following the first bleeding episode, and were frequency-matched (year of birth, catchment area) to 67 pa- tients receiving “on-demand” therapy with an early switch to “secondary prophylaxis”. In multivariate analysis adjusted for the HA mutation type and the presence or absence of thrombophilia, the Pettersson score investigated at a median age of 12.5 years in joints with at least one documented bleeding episode was not significantly different between the two patient groups (p=0.944),and no statistically significant differences were found in patients with target joints (p=0.3), nor in children in whom synovitis had occurred (p=0.77). No conclusion can be drawn from the data presented herein whether primary prophylaxis or an early start of secondary prophylaxis is superior with respect to joint outcome in children with severe HA.

Epileptic Seizure, Postictal Hemiparesis, and Hyperleukocytosis

Introduction: Acute ischemic stroke (AIS) is a rare event in infancy. Besides vasculopathy, thrombophilia, or cardiac disorders, cancer and chemotherapy are known predisposing factors for AIS. Leukemia can be associated with different abnormal coagulation parameters, but severe bleeding or thrombosis occurs rarely. Clinical Course: We report the case of a 2-year-old boy who was presented to our emergency ward after a prolonged seizure with right sided postictal hemiparesis. Cranial computed tomography scan revealed a large infarction and edema due to thrombosis of the left carotid artery, the middle cerebral artery, and the anterior cerebral artery. Laboratory workup showed 196 g/L leukocytes with 75% myeloid blast cells. Immediate exchange transfusion, hydration, and chemotherapy with cytarabine were started. During the hospital course intracranial pressure increased and the patient developed a unilateral dilated pupil unresponsive to light. Cranial computed tomography scan revealed a new infarction in the right middle cerebral artery territory. Refractory increased intracranial pressure and brain stem herniation developed, and the child died 3 days after admission to hospital. Conclusion: Seizures with postictal hemiparesis due to cerebral infarction can be a rare manifestation of acute myeloid leukemia. Leukocytosis and cancer-induced coagulopathy are main reasons for thrombosis and/or hemorrhage. High leukocyte counts need immediate interventions with hydration, careful chemotherapy, and perhaps exchange transfusion or leukapharesis. In the presence of thrombosis, anticoagulation must be discussed despite the risk of bleeding due to hyperfibrinolysis and low platelet counts. Mortality may be reduced by awareness of this rare presentation of leukemia and prompt institution of leucoreductive treatment.

Ultrasound Assisted Endovascular Thrombolysis in Adolescents: 2 Case Reports

Descending iliofemoral thrombosis in children is a rare event. Anticoagulation therapy with low-molecular-weight-heparin is standard of care. However, patency cannot be achieved in all cases, increasing the risk for rethrombosis and postthrombotic syndrome. To reduce the risk of venous valve failure in adults, local catheter-directed thrombolysis is used to reopen vessels. Two adolescent girls (17 and 15 years old) presented with acute descending iliofemoral thrombosis of the left common iliac, external, and common femoral veins. Anticoagulation with enoxaparin was started until insertion of an EkoSonic Mach 4e catheter for ultrasound-assisted local thrombolysis with recombinant tissue plasminogen activator and administration of unfractionated heparin. Success was monitored by increases in D-dimer levels and ultrasound findings. After 24 hours respectively 48 hours, complete recanalization was obtained. No complication occurred except minimal local bleeding. Screening for hereditary thrombophilia revealed a heterozygous antithrombin mutation in 1 girl (ie, the 15-year-old). May-Thurner syndrome was identified in both girls, necessitating stenting of the left common iliac veins and continuation of anticoagulation therapy with enoxaparin and acetylsalicylic acid. No rethrombosis or complications occurred during the follow-up period. Ultrasound-assisted catheter-directed local thrombolysis with the EkoSonic Mach 4e system was effective in achieving immediate recanalization of the occluded veins and should be considered in children experiencing descending iliofemoral thrombosis. The fast recanalization might reduce the incidence of postthrombotic syndrome. May-Thurner syndrome is regularly found in these patients, and if present, requires stenting of the common iliac vein to avoid early reocclusion. However, long-term patency of iliac vein stenting in children remains to be examined.

Impact of high-risk thrombophilia status on recurrence among children with a first non-central-venous-catheter-associated VTE: an observational multicentre cohort study

Deficiency of antithrombin (AT), protein C (PC) or protein S (PS) constitutes a major risk factor for venous thromboembolism (VTE). Individuals at high risk for recurrence who benefit from screening need to be identified. The primary study objective was to determine the individual recurrence risk among children with a first non-central-venous-catheter-associated VTE with respect to their thrombophilia status and to evaluate if the clinical presentation at first VTE onset differs between children with AT, PC or PS deficiency versus no thrombophilia. We calculated the absolute risk of VTE recurrence and event-free-survival adjusted for thrombophilia, age, sex and positive family VTE history in 161 consecutively enrolled paediatric VTE patients. The presence of a deficiency relative to no thrombophilia was evaluated as a potential predictor of recurrence. Predictors for recurrence were AT deficiency (hazard ratio/95% CI: 6·5/2·46-17·2) and female gender (2·6/1·1-6·35). The annual recurrence rates (95% CIs) were 5·4% (2·6-10) in AT-deficient children, 1·3% (0·3-3·8) in patients with PC deficiency, 0·7% (0·08-2·4) in the PS-deficient cohort and 0·9% (0·4-1·8) in patients with no thrombophilia. Positive family VTE history or combined thrombophilias did not predict recurrence. Given the overall annual incidence rate of recurrence of 1·5% we suggest screening for AT deficiency in children with VTE.

[Haemostatic disorders in children]

Haemorrhagic and thrombotic events occur in both children and adults. The underlying causes are congenital or acquired disorders. In contrast to haemorrhagic disorders, inherited thrombotic disorders nearly exclusively in association with additional external risk factors lead to thrombotic events predominantly during the newborn period and adolescence. It is necessary to be aware of age-specific properties of coagulation in order to correctly interpret clinical and laboratory findings and to provide optimal care for children with haemorrhagic and thrombotic complications.

Increased inhibitor incidence in severe haemophilia A since 1990 attributable to more low titre inhibitors

Many studies have reported an increased incidence of inhibitors in previously untreated patients (PUPs) with severe haemophilia A after the introduction of recombinant products. It was the objective of this study to investigate whether the inhibitor incidence has increased between 1990 and 2009 in an unselected cohort of PUPs with severe haemophilia A (FVIII< 1 %). Patients were consecutively recruited from 31 haemophilia treatment centres in 16 countries and followed until 50 exposure days or until inhibitor development. Inhibitor development was studied in five-year birth cohorts comparing cumulative incidences. Furthermore the risk for inhibitor development per five-year birth cohort was studied using multivariable Cox regression, adjusting for potential genetic and treatment-related confounders. A total of 926 PUPs were included with a total cumulative inhibitor incidence of 27.5 %. The inhibitor incidence increased from 19.5 % in 1990-1994 (lowest) to 30.9 % in 2000-2004 (highest; p-value 0.011). Low titre inhibitor incidence increased from 3.1 % in 1990-1994 to 10.5 % in 2005-2009 (p-value 0.009). High titre inhibitor incidences remained stable over time. After 2000, risk of all inhibitor development was increased with adjusted hazard ratios 1.96 (95 % CI 1.06-2.83) in 2000-2004 and 2.34 (1.42-4.92) in 2005-2009. Screening for inhibitors was intensified over this 20-year study period from a median of 1.9 to 2.9 tests/year before 2000 to 2.7 to 4.3 tests/year after 2000. In conclusion, the cumulative inhibitor incidence has significantly increased between 1990 and 2009. The high titre inhibitor incidence has remained stable.