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Reference intervals are vital for interpreting coagulation results. Current interval ranges have no upper age limit, although there is evidence that coagulation function changes with age. This study compared coagulation results from healthy people aged >60 years against adult reference intervals for routine clotting assays and thromboelastography (TEG) to determine if reference intervals are relevant to older adults.Samples from healthy blood donors aged >60 years (n=30 male, n=30 female) were tested by TEG® 6s, prothrombin time (PT), activated partial thromboplastin time (aPTT), and derived fibrinogen.All older donor-derived fibrinogen results were within the adult reference intervals, however levels were significantly higher in females. A proportion of TEG® 6s and aPTT results were not within the reference intervals. As populations around the world live longer, these findings question whether older adults require age specific coagulation reference intervals., (© 2020 by the Association of Clinical Scientists, Inc.)

Seven laboratories from 5 different countries participated in the calibration of the 7th British Working Standard (BWS) for blood coagulation factors II, IX and X. The candidate, 15/182, was assayed for Factors II and X potencies against the 4th International Standard (IS) for Factors II and X, Concentrate (11/126) and for Factor IX potency against the 5th IS for Factor IX, Concentrate (14/148). Intra-laboratory GCVs for all 3 factors were less than 10%, with the majority less than 5%. Inter-laboratory GCVs were 3.4%, 3.2% and 2.3% for FII, IX and X respectively. All participants agreed with the value assigned and preparation 15/182 was established by NIBSC in October 2017 as the 7th BWS for FII, IX, X Concentrate with potencies of 6.0 IU/ampoule, 6.7 IU/ampoule and 4.9 IU/ampoule for FII, IX and X respectively., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Prothrombin complex concentrates (PCCs) are drug products containing varying amounts of vitamin K-dependent coagulation factors II, VII, IX, and X. The evidence comparing 3-factor PCC (3-PCC) versus 4-factor PCC (4-PCC) for warfarin reversal is conflicting. It has been hypothesized that 3-PCC may be less effective than 4-PCC because of relatively lower factor VII content., Study Question: The primary objective of this study was to compare international normalized ratio (INR) reversal between 3-PCC and 4-factor PCC (4-PCC) in warfarin-treated patients. The secondary objectives include comparing blood product use, total reversal costs, and cost-effectiveness between the groups., Study Design: This was a retrospective cohort study conducted in 2 affiliated, academic institutions in the United States. Consecutive adult patients who received 3-PCC or 4-PCC for warfarin reversal were included., Measures and Outcomes: The primary outcome was adequate INR reversal defined as a final INR ≤1.5. Secondary outcomes were the utilization of plasma, red blood cells and platelets, reversal costs, and the cost-effectiveness ratio., Results: There were 89 patients who were included in the overall cohort (3-PCC = 57, 4-PCC = 32). Adequate INR reversal occurred less commonly with 3-PCC (45.6%) compared with 4-PCC (87.5%) (P < 0.001). There was no significant difference in the proportion of patients who received plasma (32% vs. 28%, P = 0.813), red blood cells (37% vs. 47%, P = 0.377), or platelets (16% vs. 28%, P = 0.180) between the 3-PCC and 4-PCC groups, respectively. The median reversal cost of 3-PCC ($3663) was lower than 4-PCC ($5105) (P = 0.001). The cost-effective ratio favored 4-PCC ($5105/87.5% = $5834) compared with 3-PCC ($3663/45.6% = $8033)., Conclusions: Four-PCC was more effective than 3-PCC with regard to INR reversal in patients taking warfarin, but blood product use was similar. Although 4-PCC is associated with increased reversal costs, it may be cost-effective in terms of INR reversal.

Background: Beriplex P/N/Kcentra/Coaplex/Confidex is a four-factor human prothrombin complex concentrate (PCC). Here, we describe the pathogen safety profile and biochemical characteristics of an improved manufacturing process that further enhances the virus safety of Beriplex P/N., Study Design and Methods: Samples of product intermediates were spiked with test viruses, and prions were evaluated under routine production and robustness conditions of the scale-down version of the commercial manufacturing process for their capacity to inactivate or remove pathogens. The PCC was characterized by determining the activity of Factor (F)II, FVII, FIX, FX, protein C, and protein S and the concentration of heparin and antithrombin III in nine product lots., Results: The manufacturing process had a very high virus reduction capacity for a broad variety of virus challenges (overall reduction factors ≥15.5 to ≥18.4 log for enveloped viruses and 11.5 to ≥11.9 log for nonenveloped viruses). The high virus clearance capacity was provided by two dedicated virus reduction steps (pasteurization and serial 20N virus filtration) that provided effective inactivation and removal of viruses and a purification step (ammonium sulfate precipitation and adsorption to calcium phosphate) that contributed to the overall virus removal capacity. The diethylaminoethyl (DEAE) chromatography and ammonium sulfate precipitation steps removed prions to below the limit of detection. The levels of different clotting factors in the final product were well balanced., Conclusion: The improved manufacturing process of Beriplex P/N further enhances the margin of pathogen safety based on its capacity to remove and inactivate a wide range of virus challenges., (© 2017 The Authors. Transfusion published by Wiley Periodicals, Inc. on behalf of AABB.)

Pathogen safety is crucial for plasma-derived clotting factor concentrates used in the treatment of bleeding disorders. Plasma, the starting material for these products, is collected by plasmapheresis (source plasma) or derived from whole blood donations (recovered plasma). The primary measures regarding pathogen safety are selection of healthy donors donating in centers with appropriate epidemiologic data for the main blood-transmissible viruses, screening donations for the absence of relevant infectious blood-borne viruses, and release of plasma pools for further processing only if they are nonreactive for serologic markers and nucleic acids for these viruses. Despite this testing, pathogen inactivation and/or removal during the manufacturing process of plasma-derived clotting factor concentrates is required to ensure prevention of transmission of infectious agents. Historically, hepatitis viruses and human immunodeficiency virus have posed the greatest threat to patients receiving plasma-derived therapy for treatment of hemophilia or von Willebrand disease. Over the past 30 years, dedicated virus inactivation and removal steps have been integrated into factor concentrate production processes, essentially eliminating transmission of these viruses. Manufacturing steps used in the purification of factor concentrates have also proved to be successful in reducing potential prion infectivity. In this review, current techniques for inactivation and removal of pathogens from factor concentrates are discussed. Ideally, production processes should involve a combination of complementary steps for pathogen inactivation and/or removal to ensure product safety. Finally, potential batch-to-batch contamination is avoided by stringent cleaning and sanitization methods as part of the manufacturing process., (© 2013 American Association of Blood Banks.)

Factor-Eight-Inhibitor-Bypassing-Activity (FEIBA) is a bypassing-agent used to control spontaneous bleeding or cover surgical interventions in Haemophiliacs who develop neutralizing antibodies against FVIII/FIX. The market lot-release of FEIBA is dependent on specific clot-based assays, carried out by both the manufacturer and regulatory authorities, relative to manufacturer's in-house standards, which are produced on a small-scale and are replaced frequently. We sought to standardize the FEIBA assay by developing a FEIBA primary standard which would be internationally available in sufficiently large quantities, with a predicted lifetime of many years. A collaborative study involving the manufacturer and three regulatory authorities, was carried out in which a candidate material, sample B (06/172), was calibrated by assays relative to the manufacturer's in-house FEIBA standards (C and D). All laboratories used their routine validated methods (16 APTT-assays, 8 ACTIN-FS-assays and 27 DAPTTIN-assays). Intra-laboratory geometric coefficients of variation (GCVs) for candidate B ranged from 3% to 29% (GCVs <9% from majority of labs). Assessment of inter-laboratory variability gave overall GCV values of 6.9% and 4.4% relative to standards C and D, respectively, for all methods. There was good agreement in potency estimation between laboratories using each of the three methods, with the overall potencies by the three methods differing by less than 10% of the overall mean, giving an overall combined potency of 28.0 units per ampoule. All participants agreed that candidate B (06/172) be established as the 1st NIBSC Working Standard for FEIBA with an assigned potency of 28.0 units per ampoule, based on combined results for both methods, relative to either standard C or D., (© 2012 Blackwell Publishing Ltd.)

Measurement of coagulation factor activity using absolute physico-chemical techniques is not possible and estimation therefore relies on comparative bioassay relative to a reference standard with a known or assigned potency. However the inherent variability of locally prepared and calibrated reference standards can give rise to poor agreement between laboratories and methods. Harmonisation of measurement between laboratories at the international level relies on the availability of a common source of calibration for local reference standards and this is provided by the World Health Organization (WHO) International Standards which define the International Unit for the analyte. This article describes the principles, practices and problems of biological standardisation and the development and use of reference standards for assays of coagulation factors, with particular emphasis on WHO International Standards for both concentrates and plasma., (Crown Copyright 2010. Published by Elsevier Ltd. All rights reserved.)

The current treatment of haemophilia with coagulation protein replacement therapy is both effective and safe. Nevertheless, this therapy requires frequent, repeated intravenous infusions and approximately 25% of treated haemophilia A patients develop antibodies to the replacement protein. Furthermore, the cost and limited availability of current concentrates has restricted access to therapy to less than 30% of the global haemophilia population. With this background, efforts are now underway to develop coagulation concentrates with enhanced biological properties that further improve the quality of care for haemophiliacs. The specific areas of enhancement that are being explored include improved biosynthetic processes, prolonging the circulating half-life and reducing concentrate immunogenicity. Coincident with these approaches, it is hoped that there will be more widespread availability of these concentrates and that their cost will be contained.

The European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) batch 1, the World Health Organisation (WHO) 3rd International Standard, Human (IS, 96/854) and the FDA Standard for human blood coagulation Factor IX concentrate have been available since 1996, following their establishment by a common collaborative study. Due to dwindling stocks of all three standards, a new WHO-EDQM-FDA tri-partite collaborative study was launched to establish replacement batches. Thirty laboratories from fourteen countries took part in the collaborative study to assign potency values to candidate preparations. Three candidates, one of recombinant and two of human plasma-derived origins, were assayed against the 3rd IS for Blood Coagulation Factor IX, Concentrate, Human (96/854). The 3rd IS for Blood Coagulation Factors II, VII, IX and X, Plasma, Human (99/826) was also included to evaluate the relationship between the factor IX plasma and concentrate unitage. Thirty-two sets of clotting assay results and two sets of chromogenic assay data were analysed. There was a significant difference in potency estimates by these two methods for the recombinant candidate (sample B) and the plasma IS (sample P). Similar potency values were obtained for the plasma derived products (monoclonal antibody- and chromatography-purified factor IX, samples C and D) by clotting and chromogenic assays. For the clotting assays, intra-laboratory variability (GCV) was found to range from 0.5 - 21.7%, with the GCV for the majority of laboratories being less than 10%. Good inter-laboratory agreement, with the majority of the GCV being less than 10% (GCV range = 4.7 - 10.6 %) was also obtained. The mean potency values estimated by the clotting assay using plasma as pre-diluent (as directed by the Ph. Eur. general chapter method) did not differ from values obtained using buffer. Taking into account the preliminary stability data, the intra- and inter-laboratory variability, and the differences between the clotting and chromogenic assay results, sample C (07/182) was established as the Human coagulation factor IX concentrate BRP batch 2, with a potency value of 7.9 IU/ampoule assigned with clotting assay results. As an outcome of this tri-partite collaborative study, the same sample C (07/182) has also been adopted as the 4th International Standard for Blood Coagulation Factor IX, Concentrate, Human by the Expert Committee on Biological Standardisation (ECBS) of the World Health Organisation (WHO), and as the replacement batch for the reference standard for Human coagulation factor IX concentrate by the FDA.

Human parvovirus, PARV4 was identified in a plasma sample from a patient presenting with symptoms resembling acute HIV infection. Further strains of PARV4 and those of a closely related variant virus, were identified in plasma pools used in the manufacture of blood derivatives. DNA sequence analysis of these strains demonstrated two distinct PARV4 genotypes. It has subsequently been proposed that transmission of PARV4 occurs by parenteral routes. To investigate the risk of contamination of plasma-derived coagulation factor concentrates, we analysed 169 lots for PARV4 DNA by polymerase chain reaction. Positive samples were confirmed by nucleotide sequence analysis and quantification of the viral load. Twenty-one lots, representing eight different products were administered until the beginning of the 1980s and were not virally inactivated. Two lots examined were used in 1997, and 146 lots representing 13 products had been administered between October 2000 and February 2003. PARV4 DNA was detected in 7(33%) of the formerly administered lots, in one lot used in 1997, and in 13(9%) recently used lots. PARV4 genotype 2 DNA was predominantly present in the older concentrates, whilst genotype 1 was found more frequently in recently used lots. In three lots, both PARV4 genotypes were detected. Viral loads ranged between <100 and 10(5.8) copies mL(-1) of product, with higher viral loads in the older concentrates. The results show that PARV4 contamination can be detected in an appreciable proportion of clotting factor concentrates. Further studies are needed to determine whether or not PARV4 contamination of coagulation factors causes harm to the product recipients.

Background and Objectives: The most common way to thaw frozen coagulation-active plasma products for transfusion is the use of a water bath with good circulation at 30-37 degrees C. The aim of this study was to perform an extensive biochemical characterization of the pharmaceutically licenced solvent/detergent-treated plasma, Octaplas, thawed using the SAHARA-III dry tempering system from the company Sarstedt GmbH, Austria. A regular water bath was used in parallel for comparison., Materials and Methods: Six batches Octaplas with different blood groups were thawed in a water bath or using the SAHARA-III dry tempering system in parallel. Thawed plasma was investigated on screening tests for blood coagulation, as well as on the activities of important coagulation factors and protease inhibitors. In addition, markers of activated coagulation and fibrinolysis were tested and von Willebrand factor multimeric analysis was performed., Results: There were neither significant differences in the blood coagulation parameters, coagulation factors, protease inhibitors, nor of markers of activated coagulation and fibrinolysis when Octaplas thawed by the two different methods was tested. The von Willebrand factor analyses showed no influence on the overall profile of the multimeric pattern when using the SAHARA-III dry tempering system., Conclusion: Octaplas can be thawed using the SAHARA-III dry tempering system without any negative influences on the demonstrated quality of this product. The SAHARA-III dry tempering system enables standardized thawing and warming procedure. Furthermore, tempering of Octaplas in the emergency unit or operating theatre, where no water baths can be utilized, is safe and can be fully endorsed.

Accurate, reliable laboratory reference ranges are essential for effective clinical evaluation and monitoring. We present robust reference ranges established for haematology, coagulation and haematinic parameters using the Sysmex XE 2100, CA 1500 and Beckman-Coulter Access analysers. Blood samples were taken from 250 healthy laboratory personnel and routine haematology, coagulation and haematinic parameter analysis performed. Our data represent findings from an extensive study to establish reference ranges in healthy adults.

The use of international biological standards during the last 30 years has proved extremely successful in promoting global harmonization of estimates between laboratories and methods. Experience has led to the identification of physical criteria essential for standards to be suitable for long-term use. High precision of liquid filling coupled with low residual moisture and oxygen and the use of sealed glass ampoules have been found consistent with homogeneous and stable International Standards (ISs). Most plasma coagulation factors and inhibitors are calibrated in International Units (IU), which are defined as the amount of analyte in 1 mL of normal pooled plasma. Adoption of the IU has provided clarity in the definition of normal and abnormal states and has facilitated dose calculation for replacement therapy. The assay of like-versus-like materials (e.g., concentrate versus concentrate) has been found to improve interlaboratory agreement and there are now both plasma and concentrate ISs available for many coagulation factors and inhibitors. Studies into the assay of recombinant factor VIII have indicated that additional measures, such as modifications to assay methodology, are necessary to reduce interlaboratory variability. This experience may prove valuable in the future, when we have to deal increasingly with the challenges to standardization associated with the products of bioengineering.

We have assessed the influence of the ABO blood group, gender and age on plasma levels of the coagulation factors II, V, VII, VIII, IX, X, XI and XII as part of a quality audit of laboratory activities. There was no statistically significant difference in gender donor age (total normal donors: n = 406, mean/median age = 46.0/47.0 years, range = 16-77 years; females: n = 177, mean/median age = 44.7/46.0 years, range = 16-75 years; males: n = 229, mean/median age = 47.0/48.0 years, range = 17-77 years). With increasing age, we observed small but statistically significant rises (linear correlation; P < 0.01 for all parameters) in factors V, VII, VIII, IX and XI. With gender, we observed higher levels (P < 0.05) in females for factors II, VII, X, IX, XI and XII. With the ABO group, we observed lower levels in the O group (versus non-O group; P < 0.05) for factors VIII, IX and XII. We could therefore define differing normal reference ranges based on the differing study data. Study findings are compared with previously published literature, and this has identified a wide diversity in normal reference ranges both between different factors and between different studies. Finally, we also performed a cross-laboratory audit of peer laboratory practice and similarly show a wide diversity in normal reference ranges used between different laboratories.

Recessive type 3 von Willebrand disease (vWD) is a severe hemophilia-like bleeding disorder caused by homozygosity or double heterozygosity for two nonsense mutations (null alleles) and characterized by a strongly prolonged bleeding time (BT), absence of ristocetin-induced platelet aggregation (RIPA), absence of von Willebrand factor (vWF) protein, and prolonged activated partial thromboplastin time (APTT) due to factor VIII (FVIIIC): deficiency. Recessive severe type 1 vWD is caused by homozygosity or double heterozygosity for a missense mutation and differs from type 3 vWD by the detectable presence vWF:antigen (Ag) and FVIII:C levels between 0.09 and 0.40 U/mL. Carriers of one null allele or missense mutations are usually asymptomatic at vWF levels of 50% of normal. Mild recessive type 1 vWD may be due to a missense mutations, or one missense mutation plus blood group O. The so-called dominant type 1 vWD secretion defect and type 1 Vicenza are caused by a heterozygous missense mutation in the vWF gene that produces a mutant vWF protein having a dominant effect on the normal vWF protein produced by the normal vWF allele with regard to the defective processing, storage secretion, and/or proteolysis of vWF in endothelial cells and clearing from plasma consistent with a type 2 phenotype of vWD. Typical type 2 vWD patients, except 2N, show a defective vWF protein, decreased ratios for vWF:ristocetin cofactor [vWF:RCo]/vWF:Ag and vWF:collagen binding factor [vWF:CB]/vWF:Ag and prolonged BT. The BT is normal and FVIII:C levels clearly are lower than vWF:Ag in type 2N vWD. Multimeric analysis of vWF in plasma demonstrates that proteolysis of vWF is increased in type 2A and 2B vWD, with increased triplet structure of each band (not present in types 2M and 2U). Proteolysis of vWF is minimal in type 2C, 2D, and 2E variants that show aberrant multimeric structure of individual oligomers. vWD 2B differs from 2A by normal vWF in platelets, and increased RIPA. RIPA is normal in mild, decreased in moderate, and absent in severe type 2A vWD. RIPA is decreased or absent in 2M, 2U, 2C, and 2D; variable in 2E; and normal in 2N and dominant type 1. vWD 2M is usually mild and features decreased vWF:RCo and RIPA, and a normal or near-normal vWF multimeric pattern in a low-resolution agarose gel. vWD 2A-like or unclassifiable (2U) is distinct from 2A and 2B and typically features low vWF:RCo and RIPA with the relative lack of large vWF multimers. vWD type 2C is recessive; the dominant type 2D is rare. The response to desmopressin acetate (DDAVP) of vWF parameters is normal in pseudo-vWD and mild type 1. The responses to DDAVP of FVIII:C and vWF parameters in vWD 2M, Vincenza, 2E, and mild 2A, 2U, and 2N are transiently good for a variable number of hours to arrest mucocutaneous bleeding episodes or to prevent bleeding during minor surgery or trauma. However, the responses are not good enough to treat major bleedings or to prevent bleeding during major surgery or trauma. The response to DDAVP of vWF parameters is poor in recessive type 3, 1 and 2C, and dominant 2A, 2B, and 2U. Proper recommendations of FVIII/vWF concentrates using FVIII:C and vWF:RCo unit dosing for the prophylaxis and treatment of bleeding episodes in type 2 disease that is nonresponsive to DDAVP and in type 3 vWD are proposed.

A variety of factor concentrates are currently available for replacement therapy for patients with hemophilia. These differ by several parameters, including source (pooled from pooled blood vs recombinant), purity, pathogen inactivation, and by the presence or absence of extraneous proteins such as albumin. The choice of replacement product reflects both safety issues of pathogen transmission or inhibitor development, and personal preferences of the patient and the physician. In general, currently available products are viral pathogen-free, although there is debate about the risk of transmission of parvovirus B19 and prion pathogens. Because of this very small risk, recombinant factor is the treatment of choice in previously untreated patients. In addition, a subset of concentrates contain factor that is activated during manufacture, yielding activated products that can be used in the treatment of patients with inhibitors. Such activated products, especially recombinant factor VIIa (rFVIIa), have also acquired several off-label indications in the management of bleeding in non-hemophiliac patients. The management of hemophilia patients with inhibitors is an ongoing challenge. Immune tolerance induction using a desensitization technique is successful in up to 90% of patients with alloantibodies against factor VIII, with greatest success seen in patients with low titer inhibitors who are treated soon after detection of an alloantibody and in whom treatment includes administration of immunosuppression along with repeated infusions of high titer concentrates. Such therapy is less successful in patients with factor IX alloantibodies. Non-hemophiliac patients with acquired inhibitors represent a unique patient population that requires special management. These patients have a mortality rate that approaches 25% because of the association of acquired inhibitors with severe bleeding complications, occurrence in a largely elderly population, and the frequent presence of an underlying, often serious, primary medical condition. Treatment consists of immunosuppression with steroids, chemotherapy, or intravenous immunoglobulin. Recent studies using rituximab for selective B-cell depletion in these patients have been very promising, although prospective controlled studies have not yet been performed. Finally, although hemophilia A and B appear to be ideal diseases to target with gene therapy approaches, the promise of this therapy remains to be realized.

The provision of concentrates of the deficient coagulation factors is an essential component of the provision of comprehensive haemophilia care. Their safety, quality and efficacy need to be assured independently of the measures dictated by the market and the individual manufacturers. Over the past 20 years, this assurance has become the role of regulatory authorities, which in the developed world have generated a framework that assesses haemophilia products as medicines in the highest category of risk relative to other therapeutic agents. Systems of official regulation mandating standards and other measures are now coupled with voluntary standards adopted by industry bodies as additional features of a comprehensive nexus of arrangements contributing to product quality and risk minimization. Currently, the regulation of products for haemophilia in less developed economies relies on reference to decisions in the first-world authorities. This may not always result in optimal outcomes as most of the haemophilia care in the developing world is through local plasma and cryoprecipitate, which are not subject to the oversight of mainstream regulators. Furthermore, the emergence of companies based outside the developed world and seeking to supply the emerging economies of the developing world with haemophilia concentrates has necessitated new strategies for regulation that are independent of the established frameworks. Overall, the principles used by mainstream agencies may be applied in all environments seeking to assure the quality of haemophilia care. Applied properly, they can contribute to maintaining the delivery of a form of therapy that is nowadays amongst the safest in therapeutic practice. A rigid interpretation can seriously impede access to treatment, and therefore the development of independent expertise and appropriate strategies in assuring product safety and quality in the developing world is essential if patient safety and access to products can be assured.

Human parvovirus B19 (B19) DNA has frequently been detected in plasma-derived coagulation factor concentrates. Furthermore, transmission of B19 infection was observed, indicating presence of the infectious virus despite routine viral inactivation/removal procedures during the manufacturing process. Recently, human parvovirus DNA isolates, variant from B19, have been identified resulting in classification of B19 virus into three distinct genotypes, with all viruses previously classified as B19 belonging to genotype 1. So far, there is no information available on contamination of clotting factor concentrates with genotype 2. Therefore, we analysed 202 different factor concentrate lots for genotype 1 and 2 DNA by PCR. Analysis of one hundred eighty-one lots representing 13 different products, administered over the last three years, was compared to 21 lots (8 products) used until the early 1980s which had not been treated by viral inactivation procedures. Genotype 1 DNA was detected in 77/181 (42.5%) currently administered lots, and 17/21 (81%) previously used lots. The level of genotype 1 DNA contamination was similar in currently and previously administered concentrates. Genotype 2 DNA was found in 5/202 (2.5%) lots, all of which were co-contaminated with genotype 1 DNA. DNA sequence analysis showed that the PCR-double positive concentrates contained typical genotype 1 and genotype 2 DNA. Because genotype 2 appears to cause a similar spectrum of diseases as genotype 1, simultaneous detection of genotype 2 by nucleic acid amplification testing (NAT), now widely applied to plasma pools for genotype 1, would give an added level of safety to blood products.

An understanding of developmental hemostasis is pivotal for optimal prevention, diagnosis, and treatment of hemostatic problems during childhood. The development of microassays in the early 1980s enabled researchers to delineate age-dependent features of the coagulation system and to establish reference ranges for healthy children of all age groups, from premature infants to adolescents. Based on the results from these studies, the hemostatic system in the young can be described as evolving, and yet functional, since healthy fetuses, infants, and children do not suffer hemorrhagic nor thromboembolic complications spontaneously or in the presence of minor challenges. Plasma concentrations of most pro- and anticoagulant proteins are decreased throughout childhood but provide an effective hemostatic balance on a lower level compared with adults. The current article describes the development of pro- and anticoagulant systems throughout childhood.

This review presents the current status on the use and benefits of viral removal filtration systems--known as nanofiltration--in the manufacture of plasma-derived coagulation factor concentrates and other biopharmaceutical products from human blood origin. Nanofiltration of plasma products has been implemented at a production scale in the early 1990s to improve margin of viral safety, as a complement to the viral reduction treatments, such as solvent-detergent and heat treatments, already applied for the inactivation of human immunodeficiency virus, hepatitis B and hepatitis C virus. The main reason for the introduction of nanofiltration was the need to improve product safety against non-enveloped viruses and to provide a possible safeguard against new infectious agents potentially entering the human plasma pool. Nanofiltration has gained quick acceptance as it is a relatively simple manufacturing step that consists in filtering protein solution through membranes of a very small pore size (typically 15-40 nm) under conditions that retain viruses by a mechanism largely based on size exclusion. Recent large-scale experience throughout the world has now established that nanofiltration is a robust and reliable viral reduction technique that can be applied to essentially all plasma products. Many of the licensed plasma products are currently nanofiltered. The technology has major advantages as it is flexible and it may combine efficient and largely predictable removal of more than 4 to 6 logs of a wide range of viruses, with an absence of denaturing effect on plasma proteins. Compared with other viral reduction means, nanofiltration may be the only method to date permitting efficient removal of enveloped and non-enveloped viruses under conditions where 90-95% of protein activity is recovered. New data indicate that nanofiltration may also remove prions, opening new perspectives in the development and interest of this technique. Nanofiltration is increasingly becoming a routine step in the manufacture of biopharmaceutical products.

Evidence based guidelines are presented on the selection and use of therapeutic products to treat haemophilia. These guidelines offer advice based on the best published scientific and medical information. They will be reviewed regularly by UKHCDO Advisory Committee. Included are details of therapeutic products available in the UK to treat patients with haemophilia and other bleeding disorders and the background information on which the recommendations are based are presented.

The clinical efficacy of the therapeutic plasma used in the treatment of congenital and acquired severe coagulopathy depends on the potency of clotting factor and inhibitor activities. The composition of plasma strongly depends on the conditions under which it is produced. A low citrate anticoagulant-to-blood ratio, short intervals between donation and plasma separation and rapid freezing markedly improve the preservation of unstable coagulation factors. The influence of different leukocyte reduction filters on plasma quality still requires clarification. Recent trials on long-term storage conditions suggest that keeping plasma at -30 degrees C or colder over a period of 24-36 months prevents substantial decrease in clotting factor activities including factor VIII (FVIII). Three types of therapeutic plasma are currently available. Quarantine-stored fresh frozen plasma (FFP) contains physiological activities of therapeutically relevant plasma proteins, but carries a risk of transmitting blood-borne viruses that cannot be detected by human immunodeficiency virus (HIV) and hepatitis B and C screening. In contrast, solvent/detergent-treated plasma (SDP) and methylene blue/light-treated plasma (MBP) is virtually free of HIV and hepatitis C virus (HCV) subtypes. Virus inactivation procedures can have the consequence of reducing several clotting factors and inhibitors in SDP and MBP to varying degrees. However, pooling of plasma units before solvent/detergent (SD) treatment results in well-standardized protein levels of SDP. At least five prospective trials and four observational studies covering different clinical settings suggest that SDP and FFP do not substantially differ in their clinical efficacy or in their tolerance. By way of contrast, there is a lack of data about the clinical efficacy and tolerance of MBP compared to FFP.

Highly purified, plasma-derived factor IX (FIX) concentrates are produced in large part by a combination of anion exchange and heparin affinity chromatography. However, the concentrates still contain some accompanying proteins. The main impurity has turned out to be the adhesive glycoprotein, vitronectin. It occurs in concentrates exclusively in its multimeric form, in contrast to the situation in plasma. The multimeric vitronectin can be removed either by nanofiltration with a crossflow system or by size-exclusion chromatography. When these FIX concentrates are used as therapeutic agents, the fact has to be taken into account that considerable amounts of multimeric vitronectin are given to the patient. The physiological consequences of the dosage of this protein have not yet been investigated. Although no thrombogenicity has been reported in connection with the above-mentioned FIX concentrates, we recommend that the impurity should be removed from the preparation with the methods described here.

Clotting factor concentrates (CFCs) have evolved substantially toward both safety from pathogens and overall final purity of the products. The array of product types for both factor VIII and factor IX CFCs ranges from so-called intermediate purity (containing multiple plasma proteins), very high purity (containing chiefly the respective purified clotting protein plus an albumin stabilizer), and recombinant CFCs (with or without albumin stabilizers). Each is discussed in the context of theoretic safety, other possible effects on the host (eg, immunogenicity), and the niche that each occupies in the armamentarium for hemophilia therapy. The difficulty in applying a cost-efficacy model for making societal choices about appropriate product selection is discussed in the context of potential or emerging threats to CFC safety (e.g., variant Creutzfeldt-Jakob disease)., (Copyright 2001 by W.B. Saunders Company.)

Acquired haemophilia is a rare, life-threatening, acquired bleeding diathesis. No general consensus exists on the best therapeutic approach. We report on the standardized approach at our institution evaluated in ten patients with acquired haemophilia. Factor VIII inhibitors were found in all patients, activities ranging from 1 to 648 Bethesda units (BU). Eight of the ten patients presented with severe bleeding. Two patients died during the acute phase, one from intracranial bleeding and one due to Mycoplasma pneumonia. One patient with mild bleeding was treated with immunosuppression alone. Two patients with factor VIII inhibitor activities below 5 BU were started on factor VIII concentrate therapy. Therapy was successful in one and was changed to recombinant human activated factor VII infusion (rFVIIa) in the other, owing to insufficient factor VIII recovery. Six patients with factor VIII inhibitor activities above 5 BU were started on activated prothrombin complex concentrate (APCC) therapy. APCC treatment was successful initially in all six patients and was changed to rFVIIa infusion in one for rebleeding. One patient did not receive any specific therapy. Immunosuppression with prednisolone (2 mg kg(-1)) was begun in nine patients and was continued with cyclophosphamide (2 mg kg(-1)) in six. A complete remission of the acquired haemophilia was found in seven of the eight patients surviving the acute phase, one had a partial remission. All patients with acquired haemophilia could be managed effectively following our standardized approach. Routine administration of immunosuppression was associated with high inhibitor elimination rates.

A retrospective case analysis of the use of Autoplex T (anti-inhibitor coagulant complex [heat treated]) at a major haemophilia treatment centre is described. Twenty-three haemophilia A patients with a history of high-titre (>10 BU), high-response inhibitors were treated for a total of 54 bleeding episodes requiring hospital admission and/or surgical intervention. Effective or partially effective haemostatic control was achieved within 72 h in 94% of reported cases (effective 85%; partially effective 9%). The incidence of adverse reactions was low and there were no thrombotic complications. In bleeding episodes for which BU titres were determined within 6 months pre- and 6 months post-treatment, there was little tendency for Autoplex T to cause an anamnestic response (1 of 19 bleeding episodes). In the three invasive surgical procedures included in the case review, coverage with Autoplex T resulted in no postoperative complications, no bleeding at the surgical site, and no postoperative haematoma. The results support the efficacy and safety of Autoplex T in the treatment of bleeding episodes and haemostatic coverage of surgical procedures in haemophilia A patients with inhibitors.

In the last years, the availability in Italy of technologically advanced products for replacement therapy has produced significant changes in the management of haemophilia and of hereditary bleeding disorders in general. With the aim of a uniform approach to treatment, the Italian Association of Haemophilia Centres express in these guidelines a consensus on therapeutic strategies designed to ensure the highest degree of safety and efficacy for the treatment of inherited coagulopathies. The guidelines provide specific recommendations for the choice of the product according to updated scientific evidence, and advice on optimal dosages for the treatment of rare bleeding disorders. The system for haemophilia care and funding in Italy is briefly described.

To examine the safety profile of products used to treat inhibitor patients unresponsive to factor VIII, a review of published clinical experience was performed. The products evaluated were activated prothrombin complex concentrates (aPCCs), such as AUTOPLEX T, porcine factor VIII and recombinant activated factor VII (rVIIa). Safety characteristics included potential for transmission of infectious agents, anamnesis, thrombogenicity, thrombocytopenia and allergic reactions. While viral transmission has been virtually eliminated, the risk is theoretically higher with plasma-derived products such as aPCC and porcine factor VIII than with rVIIa, although contamination of cultured cells is a concern. Anamnesis occurs with aPCCs and porcine factor VIII, and may induce resistance to further therapy with porcine factor VIII. Thrombosis and disseminated intravascular coagulation are very infrequently reported in patients exposed to aPCCs and rVIIa, and never with porcine factor VIII. The latter is occasionally associated with thrombocytopenia, but this uncommonly limits treatment with this agent. Lastly, allergic reactions occur with about equal frequency with all products, but anaphylaxis is mainly a concern after administration of porcine factor VIII. In conclusion, products currently available are reasonably safe. Considerations such as efficacy, availability, ease of administration and cost must also be considered in making treatment choices.

Various methods are described for the elimination of infectious viruses from activated prothrombin complex concentrates (aPCCs) and for the analysis of the final products (AUTOPLEX T and FEIBA VH). Viruses of concern in human plasma-derived products are enveloped (hepatitis B and C, cytomegalovirus, Epstein-Barr virus, and human immunodeficiency virus [HIV]) and nonenveloped (hepatitis A and parvovirus B19). Donated blood used for AUTOPLEX T is screened for antihepatitis C, HBsAg, anti-HIV types 1 and 2, and p24 antigen. Plasma pools utilized for raw materials are also tested by PCR for HIV and hepatitis C virus. Partial virus inactivation and partitioning are achieved by purification of the aPCC. Further reduction of virus infectivity is accomplished by lyophilization and dry-heat treatment. Each step undergoes virus elimination validation studies in which a relevant sample is 'spiked' with the appropriate virus or model virus. The total reduction in virus from raw material to final product can then be calculated. For AUTOPLEX T the cumulative log10 reduction factors for several viruses vary from 4.2 to 14.3. This ensures an exceptionally high margin of safety. Definitive evidence for product safety was obtained by clinical observation of treated patients. The viral inactivation process of AUTOPLEX T involves a four-tier viral safety program, including Cohn alcohol fractionation and dry-heat treatment, in place of the two-stage vapour-heating process for FEIBA.

Prothrombin complex concentrates (PCCs) have been used for over thirty years to treat or prevent bleeding due to hemophilia B, vitamin K deficiency, warfarin overdose, liver disease, or deficiency of one of the prothrombin complex factors. This article tries to answer the questions of which profile of laboratory assays is required for the establishment of the diagnosis; what are indications of replacement therapy with PCCs; how to monitor the therapeutic effect; and how to monitor a possible prethrombotic state after PCC infusion. After proposing basic, standard, and optimal profiles of hemostaseological assays, the basic principal characteristics of a quality management satisfying the requirements of good laboratory practice are discussed.

Substantial progress in virus safety has been achieved during the past 15 years. Therefore only a few virus transmissions with plasma-derived products have been observed since 1985. Specific steps to eliminate, remove, or inactivate viruses were developed. Although virus safety is of decisive importance, chemical or physical treatment during the manufacturing process need not activate labile coagulation factors that cause the risk of thrombogenicity nor need not create neoantigens that mediate the risk of inhibitor formation. Thus, any new virus elimination procedure has to be evaluated and validated for all safety aspects. A comprehensive framework of regulations and efforts has been set up involving plasma donors, donation centres, manufacturers, regulatory authorities, politicians responsible for legislation, physicians, and patients. Blood and plasma donation centres and pharmaceutic industry follow "Good Manufacturing Practice" and are subject to regular audits and official inspections. Every single donation as well as plasma pools are tested for virus markers. The final products need both a marketing authorization and official batch release; in Germany, supervised by the Paul-Ehrlich-Institute. European integration is the purpose of the European Medicines Evaluation Agency. An alert pharmacovigilance system enables scientifically adequate reactions in any case of a safety problem. The ultimate evidence of product safety is provided by clinical surveillance. By participating in clinical studies, patients themselves are able to contribute significantly to the safety of plasma-derived products. The currently achieved high level of safety should encourage us to take further steps to stabilize this success and to look for further progress, wherever possible.

Thrombogenicity of factor IX complex or prothrombin complex concentrates (PCC) is a well-acknowledged problem. The exact incidence is unknown but has decreased with the improvement of the quality of coagulation factor concentrates and a more judicious use of these products. The clinical spectrum of thrombogenicity ranges from superficial thrombophlebitis, deep-vein thrombosis and pulmonary embolism, and arterial thrombosis to disseminated intravascular coagulation. Several risk factors have been identified: (a) predisposing clinical factors (underlying disease and clinical condition), (b) therapy factors (dosing, concomitant therapy and drug interactions), and (c) quality of the PCC used. It is generally assumed that the risk of thromboembolic adverse effects is greater in patients with acquired disorders of hemostasis than in patients with inherited coagulation factor deficiencies. In hemophilia B, clinical conditions with an increased risk include large muscle hematomas, immobilization, surgery (especially orthopedic surgery), and liver disease. In acquired disorders of hemostasis, a prethrombotic state can be assumed in all patients where an indication for PCC concentrates is considered. Liver disease and/ or antithrombin deficiency are considered as major risk factors. Therapy factors with an increased risk include large, repetitive doses of PCC. It is assumed that heparin and, in the case of antithrombin deficiency, antithrombin substitution decrease the incidence of thromboembolic adverse effects. Heparin neutralisation with protamine and aprotinin therapy may be additional risk factors. The declining incidence and the recent cluster of fatal thromboembolic adverse events in Germany with one brand of PCC is strong evidence for the crucial role of the quality of PCC in the occurrence of thromboembolic adverse effects.

International standards are used to assess the potency of a variety of biological drugs employed in the field of haemostasis and thrombosis. These include therapeutic concentrates for the treatment of inherited coagulation defects, such as haemophilia, thrombolytic drugs such as streptokinase for the treatment of heart attacks, and anticoagulant drugs such as heparin. Some of these standards have existed for over 25 years, and they continue to play a vital role in ensuring consistent potency, and hence safety, of manufactured drugs. The growing complexity of new products, particularly in the area of recombinant technology, represents a continuing challenge for the field of biological standardization.