Intracranial haemorrhage in children with inherited bleeding disorders in the UK 2003-2015: A national cohort study.

INTRODUCTION: Intracranial haemorrhage in children with inherited bleeding disorders is a potentially life-threatening complication and presents a significant therapeutic challenge. AIM: To define the characteristics, management and outcomes of intracranial haemorrhage presenting in UK children ≤16 years of age with inherited bleeding disorders from 2003 to 2015. METHOD: Retrospective analysis of children treated at UK haemophilia centres. RESULTS: Of 66 children presenting with Intracranial haemorrhage (ICH), 82% had haemophilia A or B, 3% VWD and 15% a rare IBD. The IBD was a severe phenotype in 91%. The rates of ICH were 6.4 and 4.2 per 1000 patient years for haemophilia A and B, respectively. Median age at presentation was 4 months (33% neonates; 91% children <2 years of age). In neonates, delivery was spontaneous vaginal (SV) in 11, instrumental in 6, caesarean in 4 and unknown in 1. In children with haemophilia, the risk of ICH after instrumental delivery was 10.6 times greater than after SV delivery. Trauma was more common in children >2 years (67%) than in children 1 month to 2 years (18%; P = .027). Prior to ICH, only 4.5% of children were on prophylaxis. 6% of haemophiliacs had an inhibitor. The median duration of initial replacement therapy was 15 days. Mortality was 13.5%. Neurological sequelae occurred in 39% of survivors, being more common following intracerebral bleeding. In haemophilia survivors, 52% subsequently developed a FVIII inhibitor. CONCLUSION: Intracranial haemorrhage occurs most frequently in children with severe IBDs, during the first 2 years of life and in children not receiving prophylaxis. Intracranial haemorrhage often occurs without documented trauma.

The immunogenicity of ReFacto AF (moroctocog alfa AF-CC) in previously untreated patients with haemophilia A in the United Kingdom.

INTRODUCTION: Factor VIII inhibitor development is currently the most serious complication of the treatment of haemophilia A. Differences in manufacturing and the molecular structure of brands of recombinant factor VIII have led to speculation that concentrates may differ in immunogenicity. This has led to a regulatory focus on the immunogenicity of factor VIII concentrates both before and after licensure. AIM: To investigate the immunogenicity of ReFacto AF post licensure in a real-world setting in previously untreated patients (PUPs) treated exclusively with this product until at least 50 exposure days (EDs). METHODS: The United Kingdom Haemophilia Centre Doctors' Organisation (UKHCDO) National Haemophilia Database (NHD) identified a consecutive cohort of patients with severe haemophilia A (<0.01 IU/L) whose first treatment was with ReFacto AF, monitored time to inhibitor development and described associated risk factors. RESULTS: One hundred and three boys reached 50 EDs within the study period, of whom 35 developed an inhibitor (P(t ≤ 50) = 0.33, [95% CI: 0.25-0.43]), of which 15 (P(t ≤ 50) = 0.16, [95% CI: 0.10-0.25]) were high titre. Inhibitors arose after a median (interquartile range) 11 (7-16) EDs. Inhibitors were significantly associated with high-risk mutations and non-significantly associated with non-white ethnicity. Inhibitors were negatively associated with a family history of haemophilia A. High-titre inhibitors were significantly associated with a family history of inhibitors. CONCLUSION: Inhibitor incidence in a single country population of ReFacto AF PUPs was similar to that previously described. Low- and high-titre inhibitors were detected after a similar number of EDs, contrasting with previous data, probably reflecting standardized inhibitor monitoring within the United Kingdom.

Treatment of bleeding episodes in haemophilia A complicated by a factor VIII inhibitor in patients receiving Emicizumab. Interim guidance from UKHCDO Inhibitor Working Party and Executive Committee.

Emicizumab is a bispecific antibody that activates FX to FXa in the absence of FVIII. It has been shown to reduce bleeding episodes in people with haemophilia A complicated by a FVIII inhibitor. Despite the protection against bleeds, some breakthrough bleeds are inevitable and these may require additional haemostatic treatment. Emicizumab has been associated with severe adverse events when co-administered with activated prothrombin complex concentrate. To minimize the risk of adverse events, the UK Haemophilia Centre Doctors' Organisation issues the following updated interim guidance to its Inhibitor Guidelines for managing patients receiving Emicizumab based on the limit published information available in February 2018.

Pharmacokinetics, safety and efficacy of a recombinant factor IX product, trenonacog alfa in previously treated haemophilia B patients.

INTRODUCTION: Trenonacog alfa (IB1001) is a recombinant factor IX (rFIX) manufactured in Chinese hamster ovary (CHO) cells. IB1001 was evaluated in a multicentre clinical trial with haemophilia B patients. AIM: The aim was to establish IB1001 pharmacokinetic non-inferiority to comparator rFIX, safety and efficacy in previously treated patients (PTPs) with haemophilia B. METHODS: Subjects were severe or moderately severe haemophilia B adult and adolescent PTPs with no history of FIX inhibitors. RESULTS: IB1001 PK non-inferiority to comparator rFIX was demonstrated through ratio of AUC0-∞ in 32 subjects. IB1001 was well tolerated in all 76 treated subjects; the most common adverse drug reaction was headache (2.6% of subjects) and there were no reports of FIX inhibitors. Transient non-inhibitory binding FIX antibodies and anti-CHO cell protein antibodies developed in 21% and 29% of subjects respectively; no safety concerns were associated with development of these antibodies. Prophylaxis (mean duration ± SD: 17.9 ± 9.6 months, mean dose: 55.5 ± 12.9 IU/kg, median 1.0 infusion per week) was effective in preventing bleeds (median annual bleed rate: 1.52, interquartile range: 0.0-3.46). One or two IB1001 infusions resolved 84% of the bleeds, while for 84% of treatments haemostatic efficacy of IB1001 was rated excellent or good. IB1001 haemostatic efficacy for all 19 major surgeries was rated adequate or better than adequate. CONCLUSIONS: IB1001 is safe and efficacious for treatment of bleeds, routine prophylaxis and perioperative management in haemophilia B patients.

Perioperative replacement therapy in haemophilia B: An appeal to "B" more precise.

INTRODUCTION: Haemophilia B is caused by a deficiency of coagulation factor IX (FIX) and characterized by bleeding in muscles and joints. In the perioperative setting, patients are treated with FIX replacement therapy to secure haemostasis. Targeting of specified FIX levels is challenging and requires frequent monitoring and adjustment of therapy. AIM: To evaluate perioperative management in haemophilia B, including monitoring of FIX infusions and observed FIX levels, whereby predictors of low and high FIX levels were assessed. METHODS: In this international multicentre study, haemophilia B patients with FIX < 0.05 IU mL-1 undergoing elective, minor or major surgical procedures between 2000 and 2015 were included. Data were collected on patient, surgical and treatment characteristics. Observed FIX levels were compared to target levels as recommended by guidelines. RESULTS: A total of 255 surgical procedures were performed in 118 patients (median age 40 years, median body weight 79 kg). Sixty percent of FIX levels within 24 hours of surgery were below target with a median difference of 0.22 IU mL-1 [IQR 0.12-0.36]; while >6 days after surgery, 59% of FIX levels were above target with a median difference of 0.19 IU mL-1 [IQR 0.10-0.39]. Clinically relevant bleeding complications (necessity of a second surgical intervention or red blood cell transfusion) occurred in 7 procedures (2.7%). CONCLUSION: This study demonstrates that targeting of FIX levels in the perioperative setting is complex and suboptimal, but although this bleeding is minimal. Alternative dosing strategies taking patient and surgical characteristics as well as pharmacokinetic principles into account may help to optimize and individualize treatment.

The haemtrack home therapy reporting system: Design, implementation, strengths and weaknesses: A report from UK Haemophilia Centre Doctors Organisation.

INTRODUCTION: Haemtrack is an electronic home treatment diary for patients with inherited bleeding disorders, introduced in 2008. It aimed to improve the timeliness and completeness of patient-reported treatment records, to facilitate analysis of treatment and outcome trends. The system is easy to use, responsive and accessible. METHODS: The software uses Microsoft technologies with a SQL Server database and an ASP.net website front-end, running on personal computers, android and I-phones. Haemtrack interfaces with the UK Haemophilia Centre Information System and the National Haemophilia Database (NHD). Data are validated locally by Haemophilia Centres and centrally by NHD. Data collected include as follows: treatment brand, dose and batch number, time/date of bleed onset and drug administration, reasons for treatment (prophylaxis, bleed, follow-up), bleed site, severity, pain-score and outcome. RESULTS: Haemtrack was used by 90% of haemophilia treatment centres (HTCs) in 2015, registering 2683 patients using home therapy of whom 1923 used Haemtrack, entering >17 000 treatments per month. This included 68% of all UK patients with severe haemophilia A. Reporting compliance varied and 55% of patients reported ≥75% of potential usage. Centres had a median 78% compliance overall. A strategy for progressively improving compliance is in place. Age distribution and treatment intensity were similar in Haemtrack users/non-users with severe haemophilia treated prophylactically. CONCLUSION: The Haemtrack system is a valuable tool that may improve treatment compliance and optimize treatment regimen. Analysis of national treatment trends and large-scale longitudinal, within-patient analysis of changes in regimen and/or product will provide valuable insights that will guide future clinical practice.

Viscoelastometric-guided early fibrinogen concentrate replacement during postpartum haemorrhage: OBS2, a double-blind randomized controlled trial.

BACKGROUND: Postpartum haemorrhage (PPH) can be exacerbated by haemostatic failure. We hypothesized that early fibrinogen replacement, guided by viscoelastometric testing, reduces blood product usage and bleed size. METHODS: Women with PPH 1000-1500 ml were enrolled. If Fibtem A5 was ≤15 mm and bleeding continued, subjects were randomized to fibrinogen concentrate or placebo. The primary outcome compared the number of units of red blood cells, plasma, cryoprecipitate and platelets transfused. RESULTS: Of 663 women enrolled 55 were randomized. The adjusted incidence rate ratio (IRR) (95% CI) for the number of allogeneic units transfused in the fibrinogen group compared with placebo was 0.72 (0.3-1.7), P =0.45. In pre-specified subgroup analyses, subjects who had a Fibtem A5 ≤12 mm at the time of randomization and who received fibrinogen concentrate received a median (25th-75th centile) of 1 (0-4.5) unit of allogeneic blood products and had an additional 300 (100-350) ml blood loss whereas those who received placebo also received 3 (0-6) units of allogeneic blood products and had 700 (200-1550) ml additional blood loss; these differences were not statistically significantly different. There was one thrombotic event in each group. CONCLUSIONS: Infusion of fibrinogen concentrate triggered by Fibtem A5 ≤15 mm did not improve outcomes in PPH. Pre-specified subgroup analyses suggest that fibrinogen replacement is not required if the Fibtem A5 is > 12 mm or Clauss fibrinogen >2 g litre -1 , but an effect below these levels cannot be excluded. The raised fibrinogen at term appears to be a physiological buffer rather than required for haemostasis. TRIAL REGISTRATION: ISRCTN46295339 ( http://www.isrctn.com/ISRCTN46295339 , last accessed 5 July 2017), EudraCT 2012-005511-11 ( https://www.clinicaltrialsregister.eu/ctr-search/search?query=2012-005511-11 , last accessed 5 July 2017).

Viscoelastometry guided fresh frozen plasma infusion for postpartum haemorrhage: OBS2, an observational study.

BACKGROUND: Postpartum haemorrhage (PPH) can be exacerbated by haemostatic failure. Based on data from trauma studies, empirical infusions of fresh frozen plasma (FFP) are often given during severe PPH if coagulation tests are unavailable. This study observed a cohort of women with moderate/severe PPH in whom FFP infusion was guided by the use of viscoelastometric point-of-care testing (VE-POCT) and clinical assessment. METHODS: Women were enrolled into this observational study when blood loss was measured or suspected to be about 1000 mL. If Fibtem A5 determined by Rotem ® thromboelastometry remained >15 mm, or bleeding stopped, FFP was withheld. If Fibtem A5 was ≤15 mm and bleeding ongoing, women were randomized into an interventional study as previously reported. Clinical and laboratory outcomes were recorded. RESULTS: The study recruited 605 women and 98% had FFP withheld. The median (25 th -75 th centile) total blood loss was 1500 (1300-2000) mL with 300 (50-545) mL occurring after enrolment. Total blood loss was >2500 mL in 40/605 (6.6%) women. RBCs were transfused in 141/605 (23.3%) patients and 11 (1.8%) received ≥4 units. At least one invasive procedure was performed in 283/605 (46.8%) women. Level 3 care was required for 10/605 (1.7%) women. No women developed clinically significant haemostatic impairment. CONCLUSIONS: Restrictive use of FFP guided by clinical assessment of bleeding and VE-POCT is feasible and did not result in clinically significant haemostatic impairment. Studies should compare the clinical and cost effectiveness of empirical FFP infusions, according to current guidelines, with targeted use of FFP based on VE-POCT. CLINICAL TRIAL REGISTRATION: ISRCTN46295339 ( http://www.isrctn.com/ISRCTN46295339 ) (accessed July 24, 2017), EudraCT 2012-005511-11 ( https://www.clinicaltrialsregister.eu/ctr-search?query=2011-005511-11 ) (accessed July 24, 2017).

Recombinant long-acting glycoPEGylated factor IX (nonacog beta pegol) in haemophilia B: assessment of target joints in multinational phase 3 clinical trials.

BACKGROUND: The paradigm(™) 2 and 4 phase 3 clinical trials investigated the safety and efficacy of nonacog beta pegol, a recombinant glycoPEGylated factor IX (FIX) with extended half-life, in previously treated haemophilia B patients. AIM: These post hoc analyses investigated the bleeding patterns in target joints. METHODS: Patients randomized to 40 or 10 IU kg(-1) once weekly prophylaxis who had at least one target joint were included. Baseline demographics and disease-specific data were collected. Bleeding patterns were assessed, and an International Society on Thrombosis and Haemostasis (ISTH) definition of target joints was used. RESULTS: A total of 67% and 8% of patients in the 40 and 10 IU kg(-1) arm, respectively, did not experience target joint bleeds during the paradigm(™) 2 trial. Twenty-four target joints were recorded in each prophylaxis arm at baseline. During the paradigm(™) 2 trial, no bleeds were reported in 17 (71%) and 7 (29%) target joints in the 40 and 10 IU kg(-1) arms respectively. All target joint bleeds in the 40 IU kg(-1) once weekly prophylaxis arm were controlled with a single injection of 40 IU kg(-1) nonacog beta pegol. By the latest ISTH definition, 90% and 58% of target joints in the 40 and 10 IU kg(-1) arms, respectively, were no longer considered target joints at the end of the paradigm(™) 2 trial. At the end of the paradigm(™) 4 extension trial, all target joints in the 40 IU kg(-1) arm were no longer considered target joints. CONCLUSION: Routine prophylaxis with 40 IU kg(-1) once weekly nonacog beta pegol has the potential for effective management of target joint bleeds in haemophilia B patients.

Association of peak factor VIII levels and area under the curve with bleeding in patients with haemophilia A on every third day pharmacokinetic-guided prophylaxis.

INTRODUCTION: We previously showed that pharmacokinetic-guided prophylaxis (PKP) allows the dosing interval to be extended while maintaining a specific trough level. However, the associations of peak factor VIII (FVIII) levels and area under the curve (AUC) with breakthrough bleeding have not been investigated. AIM: The aim of this study was to analyse data from the PKP arm to determine whether peak FVIII levels, AUC and time with FVIII levels in a haemostatically effective range are independent predictors of bleeding during prophylaxis. METHODS: Post hoc analysis of the association of FVIII levels and AUC with annualized bleeding rate in 34 patients on PKP. RESULTS: During 1 year of PKP, 131 bleeding episodes occurred in 24/34 patients. Average peak FVIII levels ranged from 24 to 168 IU dL(-1) , with higher values associated with a decreased risk for all bleeding (joint and non-joint; P < 0.01) and joint bleeding (P < 0.01). Following rFVIII infusion, median percent of time spent with FVIII levels >20 IU dL(-1) was 22%; median AUC was 1363. Both values were significantly associated with a lower ABR when targeting a 1% trough at 72 h. CONCLUSION: When PKP was administered every third day, higher peak FVIII levels, higher AUC and more time spent per week with FVIII levels >20 IU dL(-1) provided increased protection from joint and non-joint bleeding. These data highlight the potential impact of variability in individual pharmacokinetic and bleeding risk and support the need for high peak levels and AUC in some patients treated every third day. The findings do not necessarily apply to alternate-day or other prophylactic dosing regimens.

Facilitating the implementation of pharmacokinetic-guided dosing of prophylaxis in haemophilia care by discrete choice experiment.

INTRODUCTION: Patients', parents' and providers' preferences with regard to medical innovations may have a major impact on their implementation. AIM: To evaluate barriers and facilitators for individualized pharmacokinetic (PK)-guided dosing of prophylaxis in haemophilia patients, parents of young patients, and treating professionals by discrete choice experiment (DCE) questionnaire. PATIENTS/METHODS: The study population consisted of patients with haemophilia currently or previously on prophylactic treatment with factor concentrate (n = 114), parents of patients aged 12-18 years (n = 19) and haemophilia professionals (n = 91). DCE data analysis was performed, taking preference heterogeneity into account. RESULTS: Overall, patients and parents, and especially professionals were inclined to opt for PK-guided dosing of prophylaxis. In addition, if bleeding was consequently reduced, more frequent infusions were acceptable. However, daily dosing remained an important barrier for all involved. 'Reduction of costs for society' was a facilitator for implementation in all groups. CONCLUSIONS: To achieve implementation of individualized PK-guided dosing of prophylaxis in haemophilia, reduction of bleeding risk and reduction of costs for society should be actively discussed as they are motivating for implementation; daily dosing is still reported to be a barrier for all groups. The knowledge of these preferences will enlarge support for this innovation, and aid in the drafting of implementable guidelines and information brochures for patients, parents and professionals.

The epidemiology and outcomes of women with postpartum haemorrhage requiring massive transfusion with eight or more units of red cells: a national cross-sectional study.

OBJECTIVE: To ascertain the incidence of massive transfusion (MT) in obstetrics in the UK, and describe its management and clinical outcomes. DESIGN: A population-based cross-sectional study conducted through the UK Obstetric Surveillance System (UKOSS). SETTINGS: All UK hospitals with consultant-led maternity units. POPULATION: Any pregnant woman at ≥20 weeks of gestation receiving ≥8 units of red blood cells within 24 hours of giving birth, from July 2012 to June 2013. METHODS: Prospective case identification through the monthly mailing of UKOSS. RESULTS: We identified 181 women who had undergone MT, making the estimated incidence of MT associated with postpartum haemorrhage (PPH) 23 per 100 000 maternities (95% confidence interval 19-26) per year. The median estimated blood loss was 6 l (interquartile range 4.5-8.0 l). The majority of women presented outside working hours (63%), 40% had had previous caesarean sections and 3% had normal vaginal births without risk factors. The main cause for MT was uterine atony (40%) and the main mode of birth was caesarean section (69%). Of the 181 women, 15 received >20 units of red blood cells. In total, 45% of women underwent hysterectomy, and among all causes of PPH, placenta accreta had the highest hysterectomy rate. Two women died, 82% were admitted to intensive care/high-dependency units, and 28% developed major morbidities. CONCLUSION: Massive transfusion due to PPH is associated with high rates of morbidity and hysterectomy. Clinical and research efforts should focus on approaches to recognise and optimise timely resuscitation and management of these severe cases. TWEETABLE ABSTRACT: Massive transfusion due to postpartum haemorrhage is associated with high rates of morbidity and hysterectomy.

Platelet count and transfusion requirements during moderate or severe postpartum haemorrhage.

Limited data exist on platelet transfusion during postpartum haemorrhage. We retrospectively analysed a consecutive cohort from a single centre of 347 women with moderate or severe postpartum haemorrhage, transfused according to national guidelines. Twelve (3%) women required a platelet transfusion. There were no differences between women who did and did not receive platelets with respect to age, mode of initiation of labour or mode of delivery. Women receiving a platelet transfusion had a lower median (IQR [range]) platelet count at study entry than women who did not receive platelets before haemorrhage (135 (97-175 [26-259])×10(9) .l(-1) vs 224 (186-274 [91-1006])×10(9) .l(-1) ), respectively), and at diagnosis of postpartum haemorrhage (median 114 (78-153 [58-238])×10(9) .l(-1) vs 193 (155-243 [78-762])×10(9) .l(-1) respectively). Six women were thrombocytopenic pre-delivery. The cause of haemorrhage that was associated with the highest rate of platelet transfusion was placental abruption, with three of 14 women being transfused. If antenatal thrombocytopenia or consumptive coagulopathy were not present, platelets were only required for haemorrhage > 5000 ml. Early formulaic platelet transfusion would have resulted in many women receiving platelets unnecessarily. Using current guidelines, the need for platelet transfusion is uncommon without antenatal thrombocytopenia, consumptive coagulopathy or haemorrhage > 5000 ml. We found no evidence to support early fixed-ratio platelet transfusion.

The incidence of factor VIII inhibitors in severe haemophilia A following a major switch from full-length to B-domain-deleted factor VIII: a prospective cohort comparison.

Although it has been suggested that switching of factor VIII (FVIII) products may increase inhibitor formation this is disputed. Half of UK patients changed rFVIII brands because of national contracting in 2010, presenting an opportunity to compare inhibitor incidence of switchers with non-switchers. Centres were requested to test all the patients for inhibitors prior to the switching date and 6-monthly thereafter. Positive and negative inhibitor test data were also collected to analyse for testing bias. A total of 1198 patients with severe haemophilia A and treated with Advate, Kogenate/Helixate or Refacto AF preswitch were included in the analysis, of whom 516 switched to Refacto-AF and 682 did not switch products. Five new inhibitors were reported amongst previously treated patients (>50 exposure days) with a median titre at the time of detection of 1.25 BU mL(-1) (IQR 0.7-23.05). One inhibitor occurred in a non-switcher using Kogenate, an incidence of 1.5 per 1000 treatment-years (95% CI 0.2-10.5). Four inhibitors arose in patients who had switched from Kogenate (two) or Advate (two) to ReFacto-AF, an incidence of 7.8 per 1000 treatment-years (95% CI 2.9-20.8). These incidence rates did not differ significantly from one another (incidence rate ratio 5.3 (95% CI 0.5-260.3) or from the historical rate of 6.05 inhibitors/1000 treatment-years (95% CI 5.18-7.06). Only one inhibitor (non-switcher) persisted. Non-switchers were significantly older (P = 0.03), and used significantly less FVIII per year (P = 0.005) prior to switching. Following switching, factor usage increased similarly (P = 0.53) in both groups. Switching from FLRFVIII to Refacto-AF (BDDRFVIII) was not associated with an increased inhibitor development.

Haemostatic management of obstetric haemorrhage.

The haemostatic management of major obstetric haemorrhage remains challenging, and current published guidance relies heavily on experience from the non-pregnant population and expert opinion. In recent years, an interest in the implications of relative hypofibrinogenaemia, point-of-care monitoring of coagulation abnormalities, and the potential to give goal-directed therapy to correct coagulopathies, have created the possibility of significantly challenging and changing guidance. There is evidence that the haemostatic impairment in the pregnant population is different from trauma-induced bleeding, and the type and rate of onset of coagulopathies differ depending on the underlying cause. This review examines areas such as possible intervention points, describes evidence for over-transfusion of fresh frozen plasma in some situations and challenges conventional thinking on formulaic management. It also examines the rationale for other therapeutic options, including fibrinogen concentrate and tranexamic acid.

Joint health scores in a haemophilia A cohort from Pakistan with minimal or no access to factor VIII concentrate: correlation with thrombin generation and underlying mutation.

Haemophilia A is associated with recurrent joint bleeding which leads to synovitis and debilitating arthropathy. Coagulation factor VIII level is an important determinant of bleed number and development of arthropathy . The aim of this study was to compare the haemophilia joint health score (HJHS) and Gilbert score with severity, age, thrombin generation (TG) and underlying mutation in a haemophilia A cohort which had minimal access to haemostatic replacement therapy. Ninety-two haemophilia A individuals were recruited from Pakistan. Age, age at first bleed, target joints, haemophilic arthropathy joints, HJHS and Gilbert score were recorded. A strong correlation was found between HJHS and Gilbert score (r = 0.98), both were significantly higher in severe (n = 59) compared with non-severe (n = 29) individuals before the age of 12 years (P ≤ 0.01) but not thereafter. When individuals were divided according to developmental age (<12 years, 12-16 years and >16 years), both HJHS and Gilbert score were significantly lower in the youngest group (P ≤ 0.001), there was no difference between 12-16 years and >16 years. In severe individuals there was no correlation between in vitro TG and joint score, whereas in non-severe individuals there was a weak negative correlation. In the severe group, no significant difference was observed for either joint score according to the underlying mutation type (inversion, missense, nonsense, frameshift). In this cohort of haemophilia A individuals with minimal access to haemostatic treatment, haemophilic arthropathy correlated with severity and age; among severe individuals, joint health scores did not relate to either the underlying mutation or in vitro TG.

Characterization of F8 defects in haemophilia A in Pakistan: investigation of correlation between mutation type and the in vitro thrombin generation assay.

Hereditary haemophilia A is an X-linked bleeding disorder caused by mutations in the coagulation factor VIII gene (FVIII abbreviates protein, gene symbol F8). The mutation spectrum has been reported in various populations but not in Pakistan. The aims of this study were to (i) characterize F8 mutations in a large haemophilia A cohort from Pakistan and to (ii) investigate whether in vitro thrombin generation (TG) differs according to mutation type (null compared with missense) in severe haemophilia A. One hundred individuals diagnosed with haemophilia A and 100 healthy controls were recruited in Pakistan. Phenotypic measurements were re-evaluated in Cardiff; the essential regions of F8 were screened for the causative defect. A diagnosis of haemophilia A was confirmed for 92 individuals, 7 were found to have haemophilia B and 1 did not have haemophilia. The F8 defects were characterized for 80 of the 92 haemophilia A individuals and comprised point mutations, inversions (intron 22 and intron 1) and frameshifts. Point mutations (41%) were the most frequent, followed by the intron 22 inversion (20%). Thirty novel variants were identified. Comparison of in vitro TG parameters [velocity index (VI) and peak] was made between severe individuals who had a null mutation (no FVIII) and those with a missense change (dysfunctional FVIII), no significant difference was observed. The spectrum of F8 defects in Pakistan is heterogenous; VI and peak in severe haemophilia A are not influenced by whether the underlying mutation gives rise to dysfunctional FVIII or no coagulation factor at all.

Theoretical modelling of fibrinogen supplementation with therapeutic plasma, cryoprecipitate, or fibrinogen concentrate.

BACKGROUND: We aimed to create a theoretical tool to model the effect of three haemostatic agents containing fibrinogen (therapeutic plasma, cryoprecipitate, and fibrinogen concentrate) on the patient's plasma fibrinogen level. METHODS: A mathematical model was developed step-wise. The relationship between the amount of haemostatic agent and plasma fibrinogen level was plotted for each agent. A fibrinogen concentration simulator (FCS(amount)) was developed, where the amount of haemostatic agent was calculated from patient characteristics, agent characteristics, and target plasma fibrinogen level. Refinements were introduced so that (i) FCS(amount) would account for in vivo fibrinogen recovery, (ii) circulatory volume would not increase ad infinitum with increasing amounts, and (iii) red blood cells would be included in the simulation if haematocrit decreased below a certain level. A second FCS (FCS(level)) was created to calculate fibrinogen levels resulting from specified amounts of haemostatic agents. RESULTS: Fibrinogen concentration in haemostatic agents has a critical impact on their ability to increase patients' fibrinogen levels. If the target plasma fibrinogen level approaches the concentration of the fibrinogen source, the required amounts increase exponentially; it is impossible to achieve a target above the concentration of the fibrinogen source. CONCLUSIONS: We successfully developed two theoretical tools answering the questions: 'How much therapeutic plasma, cryoprecipitate, or fibrinogen concentrate would be needed to achieve a specified target fibrinogen level?' and 'What would be the resultant fibrinogen level for a specified amount of haemostatic agent?' The current tools are not intended for clinical application, but they are potentially useful for educational purposes.

Early viscoelastometric guided fibrinogen replacement combined with escalation of clinical care reduces progression in postpartum haemorrhage: a comparison of outcomes from two prospective observational studies.

BACKGROUND: Viscoelastometric haemostatic assays (VHA) give rapid information on coagulation status, allowing individualised resuscitation. METHODS: This paper compares outcomes from two observational studies of postpartum haemorrhage (PPH) in the same institution, before and after practice changed from fixed ratio empirical transfusion of coagulation products with laboratory coagulation testing to VHA-guided fibrinogen replacement incorporated into an enhanced PPH care bundle. In both studies, all blood samples were taken near 1000 mL qualitative blood loss (QBL). In Study One, QBL started once PPH was identified, and resuscitation with coagulation blood products was empirical or based on laboratory tests of coagulation. In Study Two, QBL started at delivery and VHA was used to guide fibrinogen replacement if FIBTEM A5 was <12 mm (Claus fibrinogen ≤2 g/L) or to withhold coagulation products if FIBTEM A5 was >12 mm. RESULTS: Improved PPH outcomes were observed in Study Two, with rates of measured blood loss ≥2500 mL, ≥4 units red blood cell (RBC) transfusion, fresh frozen plasma transfusion and ≥8 units of any blood product transfusion all reduced (P < 0.01). Clinically significant improvements occurred in women with fibrinogen ≤2 g/L at study entry, where the proportion of women who received ≥4 units RBC transfusion fell from 67% in Study One to 0% in Study Two (P = 0.0007). CONCLUSIONS: These results suggest that use of VHA as part of an early bundle of PPH care targeting fibrinogen ≤2 g/L with fibrinogen concentrate reduces PPH progression. The greatest benefit was seen when fibrinogen levels were ≤2 g/L at first testing.