Pattern of bleeding in a large prospective cohort of haemophilia A patients: A three-year follow-up of the AHEAD (Advate in HaEmophilia A outcome Database) study.

INTRODUCTION: Outcome data on treatment of patients with haemophilia A spanning several years of real-world evidence collection are currently very limited. AIM AND METHODS: The global prospective long-term Advate® Haemophilia A Outcome Database (AHEAD) cohort study collects real-world data from patients with severe and moderate haemophilia. We report an interim data read-out after three years of observation. RESULTS: A total of 522 patients were enrolled from 21 countries: 334 completed year 1 follow-up, 238 completed year 2 and 136 completed year 3, with an overall follow-up of 811 patient-years. Median annual bleeding rates (ABR) were 1.7 in the prophylaxis group and 8.9 in the on-demand group at year 1 visit, 1.6 and 13.0, respectively, at year 2 visit and 2.2 and 10.3, respectively, at year 3 visit. Moreover, about 42% of patients on prophylaxis vs 12% of patients on on-demand had zero annual joint bleeding rates (AJBR). Effectiveness of prophylaxis and on-demand treatment was deemed excellent/good in the majority of cases. Octocog alfa (Advate® ) was well tolerated. The inhibitors that developed in nine patients all disappeared spontaneously. Three patients had been previously exposed to FVIII for ≤50 exposure days (EDs), 3 for >50 EDs and 3 showed a borderline positive inhibitory activity (≤0.6 BU/mL). CONCLUSIONS: These data confirm that the goal of zero bleeds is achievable, although not yet achieved in all patients. Understanding reasons behind the lower response to standard prophylaxis regimens in some patients and personalizing prophylactic treatment may further improve outcome in patients with haemophilia A.

The role of von Willebrand factor in primary haemostasis under conditions of haemodilution.

INTRODUCTION: Severe blood loss and related haemodilution during cardiac surgery result in a reduced platelet count which may lead to impaired primary haemostasis. Additionally, the reduced haematocrit lowers rheological forces in circulation and may account for lowered platelet adhesiveness and potentially reduced von Willebrand factor (VWF) activity. These mechanisms may lead to postoperative bleeding. Aim of this study was the examination of VWF activity and VWF-mediated platelet adhesion to collagen under conditions of haemodilution. MATERIALS AND METHODS: An in vitro flow chamber was utilized to examine the primary haemostasis under a high arterial shear rate of 1500s-1 at variable VWF concentrations, platelet counts and haematocrit levels. RESULTS: Under a high arterial shear rate, VWF activity is highly dependent on blood viscosity. Both VWF-collagen binding and VWF-mediated platelet adhesion to collagen were significantly increased with increasing haematocrit. Interestingly, we found slight differences in the VWF multimer sizes able to bind collagen under different shear stress conditions. Under conditions of haemodilution, platelet adhesion was strongly dependent on VWF concentration. Increasing VWF concentration improved platelet adhesiveness under low haematocrit conditions (30%) and variable platelet counts (80, 150 and 250×109/L). This effect was nearly abolished at very low platelet count levels of 50×109/L. CONCLUSIONS: VWF improves platelet function under conditions of haemodilution. Therefore, increasing VWF concentration may represent a complementary strategy to administration of platelet concentrates for the management of bleeding in thrombocytopenia.

Accuracy and consistency of anti-Xa activity measurement for determination of rivaroxaban plasma levels.

Essentials Accurate determination of anticoagulant plasma concentration is important in clinical practice. We studied the accuracy and consistency of anti-Xa assays for rivaroxaban in a multicentre study. In a range between 50 and 200 µg L-1 , anti-Xa activity correlated well with plasma concentrations. The clinical value might be limited by overestimation and intra- and inter-individual variation. SUMMARY: Background Determining the plasma level of direct oral anticoagulants reliably is important in the work-up of complex clinical situations. Objectives To study the accuracy and consistency of anti-Xa assays for rivaroxaban plasma concentration in a prospective, multicenter evaluation study employing different reagents and analytical platforms. Methods Rivaroxaban 20 mg was administered once daily to 20 healthy volunteers and blood samples were taken at peak and trough levels (clinicaltrials.gov NCT01710267). Anti-Xa activity was determined in 10 major laboratories using different reagents and analyzers; corresponding rivaroxaban plasma concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). Findings Overall Pearson's correlation coefficient of anti-Xa levels and HPLC-MS results was 0.99 for Biophen® Heparin (95% CI, 0.99, 0.99), Biophen® DiXaI (95% CI, 0.99, 0.99) and STA® anti-Xa liquid (95% CI, 0.99, 1.00). Correlation was lower in rivaroxaban concentrations below 50 µg L-1 and above 200 µg L-1 . The overall bias of the Bland-Altman difference plot was 14.7 µg L-1 for Biophen Heparin, 17.9 µg L-1 for Biophen DiXal and 19.0 µg L-1 for STA anti-Xa liquid. Agreement between laboratories was high at peak level but limited at trough level. Conclusions Anti-Xa activity correlated well with rivaroxaban plasma concentrations, especially in a range between 50 and 200 µg L-1 . However, anti-Xa assays systematically overestimated rivaroxaban concentration as compared with HPLC-MS, particularly at higher concentrations. This overestimation, coupled with an apparent interindividual variation, might affect the interpretation of results in some situations.

Impact of a product-specific reference standard for the measurement of a PEGylated rFVIII activity: the Swiss Multicentre Field Study.

INTRODUCTION: Measuring factor VIII (FVIII) activity can be challenging when it has been modified, such as when FVIII is pegylated to increase its circulating half-life. Use of a product-specific reference standard may help avoid this issue. AIM: Evaluate the impact of using a product-specific reference standard for measuring the FVIII activity of BAX 855 - a pegylated FVIII - in eight of Switzerland's main laboratories. METHODS: Factor VIII-deficient plasma, spiked with five different concentrations of BAX 855, plus a control FVIII sample, was sent to the participating laboratories. They measured FVIII activity by using either with a one-stage (OSA) or the chromogenic assay (CA) against their local or a product-specific reference standard. RESULTS: When using a local reference standard, there was an overestimation of BAX 855 activity compared to the target concentrations, both with the OSA and CA. The use of a product-specific reference standard reduced this effect: mean recovery ranged from 127.7% to 213.5% using the OSA with local reference standards, compared to 110% to 183.8% with a product-specific reference standard, and from 146.3% to 182.4% using the CA with local reference standards compared to 72.7% to 103.7% with a product-specific reference standard. CONCLUSION: In this in vitro study, the type of reference standard had a major impact on the measurement of BAX 855 activity. Evaluation was more accurate and precise when using a product-specific reference standard.

Heparin-induced thrombocytopenia in pregnancy: an interdisciplinary challenge-a case report and literature review.

Heparin-induced thrombocytopenia is a serious adverse event of anticoagulation with a high risk of thromboembolic complications. As a consequence, anticoagulants other than heparins must be administered. These may be unavailable, contraindicated during pregnancy, off-label, impractical due to short half-lives and, most importantly, may be unfamiliar to many anesthesiologists. Impaired coagulation bears the risk of adverse events following neuraxial procedures and of peripartum hemorrhage. We describe the case of heparin-induced thrombocytopenia in a 29-year-old pregnant woman at 27weeks of gestation with severe valvular heart disease.

[Screening for thrombophilia 2011: who are the candidates?]. / Thrombophiliescreening 2011: Wer soll wann untersucht werden?

Heritable thrombophilia as a concept in hemostasis has been continuously discovered parallel to the knowledge on physiology of bleeding disorders. Since the 1980s it has become increasingly popular to search for thrombophilia in patients with thromboembolism and their relatives. Although initially no direct evidence existed for any advantage for the patients, successive clinical studies have helped to understand the risk of thrombosis and to stratify the patients in relation to the thrombophilic defect. In the meantime national and international guidelines have been published, suggesting which candidates should be examined and what tests should be performed. In the present paper we summarise and explain the rationale of these guidelines from the european point of view.

Impact of loss of high-molecular-weight von Willebrand factor multimers on blood loss after aortic valve replacement.

BACKGROUND: Severe aortic stenosis is associated with loss of the largest von Willebrand factor (vWF) multimers, which could affect primary haemostasis. We hypothesized that the altered multimer structure with the loss of the largest multimers increases postoperative bleeding in patients undergoing aortic valve replacement. METHODS: We prospectively included 60 subjects with severe aortic stenosis. Before and after aortic valve replacement, vWF antigen, activity, and multimer structure were determined and platelet function was measured by impedance aggregometry. Blood loss from mediastinal drainage and the use of blood and haemostatic products were evaluated perioperatively. RESULTS: Before operation, the altered multimer structure was present in 48 subjects (80%). Baseline characteristics and laboratory data were similar in all subjects. The median blood loss after 6 h was 250 (105-400) and 145 (85-240) ml in the groups with the altered and normal multimer structures, respectively (P=0.182). After 24 h, the cumulative loss was 495 (270-650) and 375 (310-600) ml in the groups with the altered and normal multimer structures, respectively (P=0.713). Multivariable analysis revealed no significant influence of multimer structure and platelet function on bleeding volumes after 6 and 24 h. After 24 h, there was no obvious difference in vWF antigen, activity, and multimer structure in subjects with and without the altered multimer structure before operation or in subjects with and without perioperative plasma transfusion. CONCLUSIONS: The altered vWF multimer structure before operation was not associated with increased bleeding after aortic valve replacement. Our findings might be explained by perioperative release of vWF and rapid recovery of the largest vWF multimers.

Late effects on haemostasis after haematopoietic stem cell transplantation.

Allogeneic and autologous hematopoietic stem cell transplantations are important therapeutic options for patients with hematologic disorders. Hemostatic complications are frequent after hematopoietic stem cell transplantation with a considerable morbidity and mortality. The incidence of bleedings and thrombosis is highest in the first few weeks after transplantation, but may also occur later. However, beyond the first year of transplantation only limited data are available. In long-term survivors the risk for premature atherosclerosis increases over time after allogeneic hematopoietic stem cell transplantation and it is higher than in the age-adjusted general population and in recipients of autologous transplantation.

Rivaroxaban: Quantification by anti-FXa assay and influence on coagulation tests: a study in 9 Swiss laboratories.

INTRODUCTION: Rivaroxaban (RXA) is licensed for prophylaxis of venous thromboembolism after major orthopaedic surgery of the lower limbs. Currently, no test to quantify RXA in plasma has been validated in an inter-laboratory setting. Our study had three aims: to assess i) the feasibility of RXA quantification with a commercial anti-FXa assay, ii) its accuracy and precision in an inter-laboratory setting, and iii) the influence of 10mg of RXA on routine coagulation tests. METHODS: The same chromogenic anti-FXa assay (Hyphen BioMed) was used in all participating laboratories. RXA calibrators and sets of blinded probes (aim ii.) were prepared in vitro by spiking normal plasma. The precise RXA content was assessed by high-pressure liquid chromatography-tandem mass spectrometry. For ex-vivo studies (aim iii), plasma samples from 20 healthy volunteers taken before and 2 - 3hours after ingestion of 10mg of RXA were analyzed by participating laboratories. RESULTS: RXA can be assayed chromogenically. Among the participating laboratories, the mean accuracy and the mean coefficient of variation for precision of RXA quantification were 7.0% and 8.8%, respectively. Mean RXA concentration was 114±43µg/L .RXA significantly altered prothrombin time, activated partial thromboplastin time, factor analysis for intrinsic and extrinsic factors. Determinations of thrombin time, fibrinogen, FXIII and D-Dimer levels were not affected. CONCLUSIONS: RXA plasma levels can be quantified accurately and precisely by a chromogenic anti-FXa assay on different coagulometers in different laboratories. Ingestion of 10mg RXA results in significant alterations of both PT- and aPTT-based coagulation assays.

Order of application and liver toxicity in patients given BU and CY containing conditioning regimens for allogeneic hematopoietic SCT.

BU-CY is the established non-TBI-based myeloablative conditioning regimen for allogeneic hematopoietic SCT. However, liver toxicity and hepatic veno-occlusive disease (VOD) are frequent life-threatening complications. Pharmacological considerations suggest that BU can trigger toxicity of subsequent CY. Recent animal data confirmed this hypothesis. Less liver toxicity and better outcomes were observed when mice were treated with the reversed order of CY and BU. We analyzed in this study liver toxicity and outcome in patients receiving BU-CY (16 patients) or CY-BU (59 patients). Liver function differed significantly with higher levels of liver function tests between day +10 and +30, and a higher cumulative incidence of VOD in the BU-CY cohort (2/16 (12.5%) vs 0/59 (0%), P=0.006). TRM was significantly higher in patients receiving BU-CY (cumulative incidence BU-CY 45%, CY-BU 17%, P=0.02), without yet translating into a significant survival difference (incidence for survival: BU-CY 38%, CY-BU 63%; hazard ratio 1.19 for BU-CY, 95% confidence interval 0.29-4.82, P=0.80). Rates of engraftment and relapse were not different. These data support the concepts derived from animal models in favor of CY-BU compared with traditional BU-CY and form the basis for prospective controlled comparisons.

[Perioperative management of long-term medication]. / Langzeitmedikation und perioperatives Management.

Anesthesiologists and surgeons are increasingly faced with patients who are under long-term medication. Some of these drugs can interact with anaesthetics or anaesthesia and/or surgical interventions. As a result, patients may experience complications such as bleeding, ischemia, infection or severe circulatory reactions. On the other hand, perioperative discontinuation of medication is often more dangerous. The proportion of outpatient operations has increased dramatically in recent years and will probably continue to increase. Since the implementation of DRGs (pending in Switzerland, introduced in Germany for some time), the patient enters the hospital the day before operation. This means that the referring physician as well as anesthesiologists and surgeons at an early stage must deal with issues of perioperative pharmacotherapy. This review article is about the management of the major drug classes during the perioperative period. In addition to cardiac and centrally acting drugs and drugs that act on hemostasis and the endocrine system, special cases such as immunosuppressants and herbal remedies are mentioned.

[Thrombotic microangiopathy after extracorporeal circulation: important differential diagnosis]. / Thrombotische Mikroangiopathien nach extrakorporaler Zirkulation : Wichtige Differenzialdiagnose.

Thrombotic microangiopathies are characterized by platelet activation, endothelial damage, hemolysis and microvascular occlusion. This group of diseases is primary represented by thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). Patients present with microangiopathic hemolytic anemia and thrombocytopenia as well as occlusion-related organ ischemia to a variable degree. A deficiency of the metalloprotease ADAMTS-13 is a major risk for acute disease manifestation as this is a regulator of unusually large von Willebrand factor (vWF) multimers, which are extremely adhesive and secreted by endothelial cells. In classical TTP an ADAMTS-13 activity below 5% is specific, whereas in other forms of thrombotic microangiopathies activity of ADAMTS-13 ranges from very low to normal. Symptoms of different forms of thrombotic microangiopathy are frequently overlapping and a clear classification according to clinical criteria is often difficult. Due to a high mortality, particularly of TTP, immediate diagnosis and therapy are essential. In this article two cases of thombotic microangiopathy after cardiac surgery are reported. After exclusion of TTP and HUS as well as other etiologies of thrombotic microangiopathy a relationship between the use of extracorporeal circulation and the pathogenesis of thrombotic microangiopathy is assumed.

A large Swiss family with Bernard-Soulier syndrome - Correlation phenotype and genotype.

Bernard-Soulier syndrome (BSS) is a rare, autosomal recessive inherited bleeding disorder associated with thrombocytopenia, thrombocytopathy and giant platelets. BSS is caused by genetic alterations of the glycoprotein (GP) Ib/V/IX complex. We report on a large Swiss family of whom four family members suffer from BSS. Here, a homozygous missense mutation in position 1829 (A(R)G) of the GPIX gene constituting a N45S substitution is the cause for the bleeding symptoms. A total of 38 family members within two generations were analyzed regarding the N45S mutation by DNA sequencing and restriction fragment length polymorphism. The laboratory parameters which are characteristically for BSS such as platelet count, platelet volume and the expression of CD42a (GPIX), CD42b (GPIbalpha) and CD41 (GPIIb) were measured for all 38 individuals. The four homozygous patients showed bleeding symptoms, thrombocytopenia and giant platelets. In these patients, the expression of CD42a (GPIX), CD42b (GPIbalpha) was diminished. Interestingly, the intensity of the bleeding symptoms of the 4 homozygous family members seemed to vary although they carry the same mutation. The 24 heterozygous carriers did not differ significantly from their 10 wildtype family members regarding bleeding symptoms and laboratory analysis.

Hypersensitivity reactions to anticoagulant drugs: diagnosis and management options.

Anticoagulants, including heparins, coumarins, hirudins, and some of the previously used plasma volume expanders, belong to the most widely used drugs. Hypersensitivity reactions from these agents are uncommon. However, they may have a considerable impact on patient safety and treatment decisions. Therefore, early diagnosis of potentially life-threatening adverse events and identification of alternatives is clinically important. This review contains an update on current knowledge about hypersensitivity reactions caused by the different anticoagulants. In addition, it discusses pathophysiologic mechanisms, diagnostic possibilities, and management options. The most common hypersensitivity reactions are erythematous plaques, occurring with a delay after subcutaneous application of heparins. Seldom they turn into maculopapular exanthema. Other hypersensitivity reactions are rare but may be life-threatening, e.g. skin necrosis because of heparin-induced thrombocytopenia. Skin and provocation tests with immediate and late readings are the most reliable diagnostic tools for heparin- or hirudin-induced urticaria/anaphylaxis or heparin-induced delayed plaques. If necrosis from heparins or coumarins is suspected, skin tests are contraindicated. In anaphylactic reactions caused by dextrans or hydroxyethyl starch skin tests are useless. Most in vitro tests have a low sensitivity and are not generally available. Therefore, in some anticoagulant-associated hypersensitivity reactions detailed allergologic investigation may help to identify safe treatment alternatives. However, several tests may be needed, and the procedures are usually time-consuming.

Transplant-associated microangiopathy (TAM) in recipients of allogeneic hematopoietic stem cell transplants.

We studied occurrence, risk factors and outcome of patients with transplant-associated microangiopathy (TAM) after allogeneic stem cell transplantation (HSCT). A total of 221 consecutive patients were transplanted between 1995 and 2002. TAM is defined as evidence of hemolysis and schistocytes in the first 100 days. Outcomes analyzed included TAM and overall survival. Of 221 patients, 68 had TAM. The cumulative incidence was 31 (25-38)% at 100 days. Patients with TAM had higher LDH, higher bilirubin, higher creatinine and more often neurologic symptoms. TAM was not associated with stem cell source, cyclosporine levels and was not more frequent in recent years. In multivariate analysis, risk factors for TAM included donor type, age, gender, ABO-incompatibility and acute graft-versus-host disease (aGvHD). In patients with TAM, 1-year survival was lower than in patients without TAM (27 +/- 18% for TAM with high schistocyte counts; 53 +/- 15% for TAM with low schistocyte counts; vs 78 +/- 7% in patients without TAM; P<0.0001). TAM was independently associated with mortality adjusting for donor type, age and aGvHD occurrence and severity. TAM is frequent after HSCT and is associated with mortality even after adjustment for aGvHD grade. Risk factors of TAM are similar to aGvHD. TAM may represent endothelial damage driven by donor-host interactions.

[Anticoagulants and antiplatelet agents in pregnancy]. / Gerinnungshemmende Medikamente in der Schwangerschaft.

Anticoagulants and antiplatelet agents are currently used during pregnancy as treatment or prophylaxis for thromboembolic disease. Main adverse events of these agents are bleeding episodes, which put the pregnancy at risk. Unfractionated and low molecular weight heparins are first-line treatment or prophylaxis for thromboembolism. If an antiplatelet agent is needed, aspirin alone or in combination with heparins can be safely administered. Coumarine derivatives are still contraindicated during pregnancy because of teratogenicity and/or bleeding. No adequate data are yet available on the safety profile of the new antiplatelet agents or the direct thrombin inhibitors. Special considerations are discussed on the risks of regional anesthesia, as well as on nursing during anticoagulation.