Diagnosis and management of acquired coagulation inhibitors: a guideline from UKHCDO

Diagnosis and management of factor XI alloinhibitors in patients with congenital factor XI deficiency-A large single-centre experience

INTRODUCTION

Factor (F) XI deficiency is an inherited bleeding disorder with increased prevalence in Ashkenazi Jews where it is mainly caused by two variants, p.Glu135* (type II, leading to a null allele) and p.Phe301Leu (type III, missense variant). Inhibitor development is rare, and only seen in severe FXI deficiency (<20 IU/dL) upon exposure to plasma-based products. We report our experience of a large cohort of patients with severe FXI deficiency, including seven patients who developed FXI alloinhibitors, their presentation, natural history and subsequent perioperative management.

METHODS

A single-centre retrospective database review of patients with FXI deficiency, including those who have subsequently developed inhibitors, and extraction of clinical, laboratory and genotype data, including operative management records.

RESULTS

A total of 682 patients were identified with FXI deficiency, of whom 113 had FXI < 20 IU/dL and 42 had FXI ≤ 1 IU/dL. Factor XI inhibitors were seen in seven patients, six of whom were homozygous for the type II variant (prevalence of inhibitor with this genotype of 30%, risk of inhibitor upon plasma exposure 50%). FXI inhibitors were not seen, despite similar exposures, in patients with other genotypes. No alteration in bleeding phenotype occurred after inhibitor development and subsequent surgery was managed on 13 occasions with recombinant factor VIIa (rFVIIa), including low doses (15-30 µg/kg), with good haemostasis. The inhibitor spontaneously disappeared in four of seven patients over 1-22 years.

CONCLUSION

FXI inhibitors were only observed in severe FXI deficient patients homozygous for p.Glu135* (null allele) upon plasma or FXI concentrate exposure, with a 30% prevalence. The bleeding phenotype was not altered and inhibitors may disappear with time. Adequate haemostasis in the perioperative setting is achievable with low doses of rFVIIa.

Inhibitor eradication and treatment for acquired hemophilia A

INTRODUCTION

Acquired hemophilia A (AHA) is a rare hemorrhagic autoimmune disorder characterized by autoantibodies against coagulation factor VIII (FVIII). In approximately half of the cases AHA does not recognize any cause (idiopathic form), while in the other cases it may be triggered by autoimmune disorders, cancers, drugs, infections, or pregnancy. Besides treating the underlying disorder, specific AHA treatment includes management of bleeding, if necessary, and inhibitor eradication.

AREAS COVERED

This narrative review summarizes the main epidemiological, clinical, laboratory, and therapeutic characteristics of AHA. In particular, it is focused on the current therapeutic options for the inhibitor eradication, also showing the latest findings on the innovative therapies. A literature search strategy was performed, without temporal limits, through Medline and PubMed electronic databases.

EXPERT OPINION

Various first-line and second-line immunosuppressive agents are currently available for the management of AHA. Among the latter, the anti-CD20 monoclonal antibody rituximab has been the object of intense research during the last years from investigators as innovative promising eradicating therapy for AHA. Preliminary data from the studies support the use of this drug as a first-line option for newly diagnosed AHA cases.

Comprehensive comparison of global coagulation assays to differentiate lupus anticoagulant from acquired hemophilia A in patients with prolonged APTT

There is no established method for differentiating acquired hemophilia A (AHA) from lupus anticoagulant (LA) positivity because both present with prolonged activated partial thromboplastin time. We compared various parameters of rotational thromboelastometry (ROTEM), thrombin generation assay (TGA), and clot waveform analysis (CWA) in patients with AHA (n = 10) and LA (n = 44). Compared with AHA, possible (n = 12) and definite (n = 32) LA showed significantly shorter clotting time (CT) in NATEM mode of ROTEM (> 3600 vs. 501/533). In TGA, peak height was significantly lower in AHA (16 vs. 242/174 nM). In CWA, CT was significantly longer (81 vs. 36/41 s) and Ad|min1| was lower (2.1 vs. 8.7/6.7) in AHA. Notably, CT by NATEM and peak height in TGA completely discriminated between AHA and LA, whereas Ad|min1| did not discriminate between them in 4 cases of AHA and 1 of LA. Comparison of 3 patients with both AHA and LA against a patient with only LA and markedly low FVIII activity (3.5%) showed that both CT by NATEM and peak height of TGA precisely classified the former 3 cases as AHA and the latter 1 case as LA, whereas Ad|min1| classified all 4 cases as AHA. ROTEM and TGA can comparably distinguish between AHA and LA.

Lupus Anticoagulant Detection under the Magnifying Glass

Diagnosis of antiphospholipid syndrome (APS) requires the presence of a clinical criterion (thrombosis and/or pregnancy morbidity), combined with persistently circulating antiphospholipid antibodies (aPL). Lupus anticoagulant (LA) is one of the three laboratory parameters (the others being antibodies to either cardiolipin or β2-glycoprotein I) that defines this rare but potentially devastating condition. For the search for aCL and aβ2-GP-I, traditionally measured with immunological solid-phase assays (ELISA), several different assays and detection techniques are currently available, thus making these tests relatively reliable and widespread. On the other hand, LA detection is based on functional coagulation procedures that are characterized by poor standardization, difficulties in interpreting the results, and interference by several drugs commonly used in the clinical settings in which LA search is appropriate. This article aims to review the current state of the art and the challenges that clinicians and laboratories incur in the detection of LA.

Acquired hemophilia A developing in the perioperative period of pancreatoduodenectomy: a report of two cases

BACKGROUND

Acquired hemophilia A (AHA) is a rare disease characterized by a prolonged activated partial thromboplastin time (aPTT) and the production of coagulation factor VIII inhibitors. We encountered two cases of AHA in the perioperative period of pancreatoduodenectomy (PD).

CASE PRESENTATION

Case 1: A 76-year-old woman with intraductal papillary mucinous carcinoma developed acute cholecystitis 5 days before PD. Despite immediate improvement in her acute cholecystitis with biliary drainage and antibiotics, her aPTT level was prolonged (55.9 s). PD was performed as scheduled. On postoperative day (POD) 2, she developed intra-abdominal hemorrhaging that required reoperation. However, intra-abdominal bleeding and concomitant anemia persisted after reoperation. On POD 13, she was diagnosed with AHA based on the detection of an inhibitor of coagulation factor VIII. Despite hemostatic and immunosuppressive treatment, including massive blood transfusion, her general condition gradually worsened due to continuous bleeding and secondary infections. She ultimately died of multiple organ failure on POD 71. Case 2: An 82-year-old man received PD for distal cholangiocarcinoma. On POD 3, a small amount of blood via abdominal drainage was observed. On POD 4, his aPTT level was prolonged (61.5 s). On POD 8, subcutaneous hemorrhaging of the median wound was observed, and corticosteroids were administered under suspicion of AHA on POD 9. On POD 15, an inhibitor of FVIII was detected, and he was diagnosed with AHA. On POD 17, the aPTT level had normalized, and an inhibitor of FVIII was undetectable. On POD 41, he was discharged without any serious hemorrhagic events.

CONCLUSIONS

AHA may be more frequent than previously reported. When unexplained prolonged aPTT or bleeding symptoms are observed, it is important to keep AHA in mind during the perioperative period of invasive surgery.

Risk factors, treatment and survival rates of late-onset acquired haemophilia A: A cohort study from the Shizuoka Kokuho Database

INTRODUCTION

Acquired haemophilia A (AHA) is a rare disease. The risk factors have yet to be studied.

AIM

We aimed to identify risk factors for late-onset AHA in Japan.

METHODS

A population-based cohort study was conducted using data from the Shizuoka Kokuho Database. The study population was defined as individuals aged ≥60 years. Cause-specific Cox regression analysis was performed to calculate hazard ratios.

RESULTS

Of 1,160,934 registrants, there were 34 patients with newly diagnosed AHA. The mean follow-up period was 5.6 years, and the incidence of AHA was 5.21 per million person-years. Myocardial infarction, diabetes mellitus, solid tumors, antimicrobial agents, phenytoin and anti-dementia drugs, which showed significant differences in the univariate analysis, were excluded from the multivariable analysis because of the small number of cases. Multivariable regression analysis showed that the presence of Alzheimer's disease (hazard ratio [HR]:4.28, 95% confidence interval [CI]:1.67-10.97) and rheumatic disease (HR:4.65, 95% CI:1.79-12.12) increased the risk of AHA development.

CONCLUSION

We found that comorbid Alzheimer's disease is a risk factor of AHA incidence in the general population. Our findings provide insight into the etiology of AHA, and the proof of the coexistence of Alzheimer's disease may support the recent notion that Alzheimer disease is an autoimmune disease.

Acquired Hemophilia A: An Update on the Etiopathogenesis, Diagnosis, and Treatment

Acquired haemophilia A (AHA) is a rare bleeding disorder caused by inhibitory autoantibodies against coagulation factor VIII (FVIII). AHA is a disease that most commonly affects the elderly but has also been observed in children and in the postpartum period. AHA is idiopathic in 50% of cases and is associated with autoimmune diseases, malignancies, and infections in the remaining 50%. Recently, cases of association between AHA, COVID-19 vaccination, and infection have been reported in the literature. For diagnoses, determining FVIII levels is crucial to distinguish the different causes of aPTT prolongation. Treatment of AHA is based on bypassing agents (recombinant factor VIIa, activated prothrombin complex concentrate) and porcine FVIII to control the bleeding and immunosuppressive therapy (corticosteroids, rituximab, cyclophosphamide) to suppress autoantibody production. It is important to start a prophylactic regimen to prevent further bleeding episodes until the inhibitor is negative. Recently, the series of cases reported in the literature suggest that emicizumab may provide effective and safe haemorrhage prophylaxis in the outpatient setting.

Acute-type acquired hemophilia A after COVID-19 mRNA vaccine administration: A new disease entity?

Acquired hemophilia A (AHA) is a rare autoimmune bleeding disorder. Various autoimmune diseases, including AHA, have been reported to occur after the administration of mRNA COVID-19 vaccines. However, the characteristics of these AHA cases remain unclear. We report a case in which AHA arose in a young patient after the administration of an mRNA COVID-19 vaccine, but improved rapidly. The patient's factor VIII (FVIII) inhibitor titer spontaneously decreased to less than half of that seen at diagnosis. One week after the initial immunosuppressive therapy, the FVIII inhibitor had disappeared. Our case suggests that AHA that arises in young patients after COVID-19 vaccination may resolve spontaneously, and the levels of FVIII inhibitors may decrease more rapidly in such cases than in idiopathic AHA. Unlike for immune thrombocytopenic purpura (ITP), no acute type of AHA has been recognized. This case suggests that just as there is an acute type of ITP that develops in children/after vaccination, there may be an acute type of AHA that arises in young patients that receive mRNA COVID-19 vaccines.

A Rapid and Satisfactory Outcome with Combined Immunosuppressive Therapy in Acquired Haemophilia A with Underlying Tuberculosis

Acquired haemophilia A (AHA) is a rare disorder with an incidence of 1.5 cases per million per year in the United Kingdom. The incidence could be underestimated due to difficulty in diagnosis and also due to the fact that people with low titre inhibitor levels are asymptomatic. It is usually a disease affecting elderly but a disease peak in the younger population is known. The common underlying diseases are autoimmune disorders, malignancies, infections, and drugs. However, approximately 50% of the cases do not have a specific aetiology and about 10% will not have bleeding manifestations. Therefore, an isolated prolongation of APTT should be evaluated, especially prior to any haemostatic challenges. We report a case of a middle-aged man who presented with bleeding due to AHA associated with high inhibitory titres and active pulmonary tuberculosis. He was treated with both antituberculous and combined-aggressive immunosuppressive therapy which resulted in satisfactory disease remission.

A patient with bullous pemphigoid presenting with haemorrhagic oral erosions, oral haematoma and haemoptysis

We present a case of a patient with bullous pemphigoid presenting with acquired haemophilia A. This is characterized by formation of antibodies or inhibitors against coagulation Factor VIII, leading to a prolonged activated partial thromboplastin time with normal prothrombin time and international normalized ratio. Our case emphasizes the need for increased awareness among dermatologists of this uncommon and potentially life-threatening condition.

Acquired haemophilia A in a patient who is a Jehovah's Witness

We detail the case of a man in his 80s who was a Jehovah's Witness, presenting to hospital for the second time in 1 week with atraumatic, severe bruising affecting his right thigh and flank. He was subsequently diagnosed with idiopathic acquired haemophilia A (AHA) and was urgently treated with recombinant factor concentrate and immunosuppressive therapy. Management of his bleeding disorder and resultant severe anaemia was adapted in line with his religious beliefs. AHA is a rare bleeding disorder which should be considered in patients with an isolated prolonged activated partial thromboplastin time and a history of recent or acute bleeding. Prompt diagnosis and management are essential as delays may result in increased mortality. Given that this patient declined blood transfusion, management of his bleeding disorder presented a unique challenge.

An unexpected turn of events: A rare case of Acquired Haemophilia A after a violin spider bite

We report an interesting clinical case of Acquired Haemophilia A (AHA) after a probable Loxosceles rufescens spider bite in a 73- year-old woman, admitted to an Emergency Department (ED) of Central Italy during April 2019. AHA is a rare disease, whose acute clinical manifestations are not widely known by most ED physicians; its prompt recognition and treatment are crucial to avoid fatal bleeding. In particular, the development of AHA after a violin spider bite (another rare and poorly characterized clinical condition) has never been described. Therefore, our case report could provide useful insight into the understanding and treatment of such unusual and possibly life-threatening conditions.

Risk and Management of Intracerebral Hemorrhage in Patients with Bleeding Disorders

Intracerebral hemorrhage (ICH) is the most dreaded complication, and the main cause of death, in patients with congenital bleeding disorders. ICH can occur in all congenital bleeding disorders, ranging from mild, like some platelet function disorders, to severe disorders such as hemophilia A, which can cause catastrophic hemorrhage. While extremely rare in mild bleeding disorders, ICH is common in severe coagulation factor (F) XIII deficiency. ICH can be spontaneous or trauma-related. Spontaneous ICH occurs more often in adults, while trauma-related ICH is more prevalent in children. Risk factors that can affect the occurrence of ICH include the type of bleeding disorder and its severity, genotype and genetic polymorphisms, type of delivery, and sports and other activities. Patients with hemophilia A; afibrinogenemia; FXIII, FX, and FVII deficiencies; and type 3 von Willebrand disease are more susceptible than those with mild platelet function disorders, FV, FXI, combined FV-FVIII deficiencies, and type 1 von Willebrand disease. Generally, the more severe the disorder, the more likely the occurrence of ICH. Contact sports and activities can provoke ICH, while safe and noncontact sports present more benefit than danger. An important risk factor is stressful delivery, whether it is prolonged or by vacuum extraction. These should be avoided in patients with congenital bleeding disorders. Familiarity with all risk factors of ICH can help prevent occurrence of this diathesis and reduce related morbidity and mortality.

Could a Haematoma Be Due to an Acquired Phenomenon?

Acquired hemophilia, as opposed to congenital hemophilia, develops in individuals with no previous history of bleeding disorder with almost similar numbers of males and females affected. It is predominantly a disease of the elderly. It is an autoimmune disorder and occurs when the immune system produces antibodies that mistakenly attack healthy tissue, specifically the clotting factors, in particular clotting factor VIII. As a result, affected individuals develop abnormal uncontrolled bleeding into the muscles, soft tissues, and the skin and it can occur spontaneously during surgery, or following trauma, and potentially cause life-threatening bleeding complications in severe cases. The affected individuals may remain undiagnosed or be misdiagnosed, making it difficult to determine the actual frequency of the disorder in the general population. The clinical presentation should suspect it with confirmation by an abnormal coagulation test. Typical laboratory results with a recent onset of abnormal bleeding and an isolated prolongation of the activated partial thromboplastin time (APTT), especially in the elderly and peri- and post-partum women, should raise eyebrows. We present two cases following different symptomatology and emphasize the clinical challenges for junior medical doctors who receive patients on the front end. We hope to emphasize understanding simple coagulation blood results followed by a meaningful discussion with the hematology team towards appropriate and timely management of the bleeding diathesis. We hope this case series report will help junior medical doctors manage patients appropriately and consult with their hematology colleagues.

The Clinical Genetics of Hemophilia B (Factor IX Deficiency)

Hemophilia B (HB) is a bleeding disorder caused by deficiency of or defect in blood coagulation factor IX (FIX) inherited in an X-linked manner. It results from one of over 1000 known pathogenic variants in the FIX gene, F9; missense and frameshift changes predominate. Although primarily males are affected with HB, heterozygous females may have excessive bleeding due to random or non-random X chromosome inactivation; in addition, homozygous, compound heterozygous, and hemizygous females have been reported. Somatic and germinal mosaicism for F9 variants has been observed. Development of antibodies to FIX treatment products (inhibitors) is rare and related to the type of causative variant present. Treatment is with products produced by recombinant DNA technology, and gene therapy is in clinical trials. Genetic counseling with up-to-date information is warranted for heterozygotes, potential heterozygotes, and men and women affected with HB.

Diagnosis and Management of Acquired Hemophilia A: Case Reports and a Literature Review

Background

Acquired hemophilia A (AHA) is a potentially life-threatening autoimmune hemostatic disorder where autoantibodies that disrupt the functions of factor VIII (FVIII) are present in the circulation. The early diagnosis of AHA is difficult since the symptoms of AHA differ from those of congenital hemophilia A. Furthermore, the management of AHA is also more complex due to the presence of autoantibodies against FVIII (FVIII inhibitors). Here, we present three case reports and conduct a literature review of AHA with the aim to increase awareness and knowledge regarding the diagnosis and treatment of AHA. Case Presentations. We present three patients diagnosed with AHA in these case reports. The first patient was a young female, while the second and third patients were middle-aged and elderly males, respectively. All patients presented with a chief complaint of bruises without hemarthrosis and a history of bleeding. Laboratory examinations of the patients revealed isolated prolonged aPTT, normal PT, and the presence of autoantibodies against factor VIII, which are characteristics of AHA. Patients were then treated with corticosteroids to reduce the titer level of autoantibodies and received factor VIII transfusion to stop bleeding.

Conclusion

AHA can be suspected in patients presenting with symptoms of bruises without hemarthrosis and without the history of bleeding. Isolated aPTT elevation with normal PT should raise high suspicion of AHA. The presence of FVIII inhibitors can help to confirm the diagnosis of AHA. Treatment consists of factor VIII transfusion and corticosteroid therapy. Bypassing agents are recommended as an alternative to FVIII transfusion.

Characterizing hospital pathways for the care of acquired hemophilia in France using comprehensive national health data

PURPOSE

Acquired hemophilia (AH) is a rare, serious bleeding disorder most often associated with older age and life-threatening complications. The patient care pathway for AH is complex because of the different types of bleeding, the presence of comorbidities, and the heterogeneity of medical specialists who care for these patients.

METHODS

This observational study used the French national PMSI (Programme de médicalisation des systèmes d'information) database to characterize patients with AH in real-life practice and analyze their hospital pathway. In total, 180 patients with AH were identified over a 5-year study period (January 2010 to December 2014), based on three criteria: bypassing agent use, International Classification of Diseases, 10th revision code allocation, and aged over 65 years. Comparison of the incidence rate of AH versus registry data validated the PMSI as an epidemiological database.

RESULTS

Rituximab was prescribed more often (60/180; 33.3%) than expected following guidelines and was associated in half of cases to early infections (32/60; 53.3%), surgery procedures were frequently performed during the year before AH onset (29/159; 18.2%), which may suggest a triggering effect, extended hospital stays (median: 20 days) and mortality remaining high (66/180; 36.7%) that occurred mainly during the first month after AH diagnosis. Median costs and number of injections were comparable between recombinant activated factor VII and plasma-derived activated prothrombin complex concentrate.

CONCLUSION

These findings could inform future medico-economic approaches in this AH population (duration of stays, bypassing agents, rituximab use, comorbidities, hospitalizations with infections).

Feasibility of therapeutic plasma exchange-based combination therapy in the treatment of acquired hemophilia A: A retrospective 6 case series

Poor availability and a lack of affordability of bypassing agents (recombinant activated factor VII and activated prothrombin complex concentrate) in west China prompted us to investigate an alternative cost-effective combination therapy. We aimed to explore the feasibility of therapeutic plasma exchange (TPE)-based combination therapy in the treatment of acquired hemophilia A (AHA).We retrospectively investigated the clinical features of AHA in 6 patients who were treated with a combination of TPE, corticosteroids, and rituximab in our department for 9 years between January, 2011 and December, 2019.We examined 1 male and 5 female patients. The median age at diagnosis of AHA was 51 years (18-66 years). In all patients, FVIII activity levels were low (median: 1.5%; 1-3%), FVIII inhibitor titers were high (median: 24.5 BU/mL; 13.2-48.6 BU/mL), and activated partial thromboplastin time was markedly prolonged (median: 99.4 s; 60.9-110.1 s). They underwent 2 to 8 cycles of plasma exchange and were given varying combinations of dexamethasone, methylprednisolone, prednisone, and rituximab. After TPE bleeding gradually stopped, and activated partial thromboplastin time decreased. After 3 months of treatment, FVIII inhibitors completely disappeared.TPE when combined with corticosteroids and rituximab, as adjunctive immunosuppressive agents, may be an effective and reliable treatment for AHA. When there is no alternative, intensive first-line treatment including TPE may be lifesaving.

New Developments in Diagnosis and Management of Acquired Hemophilia and Acquired von Willebrand Syndrome

Acquired hemophilia A and acquired von Willebrand syndrome are rare, but life-threatening bleeding disorders that require prompt diagnosis and treatment by hematologists. Acquired hemophilia A is defined as an acquired severe bleeding tendency caused by autoantibody formation against coagulation factor VIII. Acquired von Willebrand syndrome is characterized by a new onset bleeding tendency caused by a reduced concentration and/or function of von Willebrand factor. These disorders are associated with a variety of underlying disorders, including various hematological malignancies, for example, plasma cell disorders, lymphoproliferative disorders, monoclonal gammopathy of undetermined significance, and myeloproliferative neoplasms. It is of utmost important to recognize these acquired bleeding disorders in these patients who are at risk for severe bleeding, and to perform additional diagnostic hemostasis laboratory evaluation. This will enable immediate diagnosis of the acquired bleeding disorder and management of both the bleeding episodes and the causative underlying disorder. In recent years, several new etiological factors for acquired hemophilia A, such as treatment with immune checkpoint inhibitors or DPP-4 inhibitors and SARS-CoV2 infection, and for acquired von Willebrand syndrome, for example, left ventricular assist devices, have been identified and also new treatment options have become available. In this concise review, the most recent data on etiology, diagnosis, and treatment of acquired bleeding disorders are presented and discussed.

Treatment of high-risk bleeding with susoctocog alfa in a patient with acquired haemophilia A and a nosocomial severe acute respiratory syndrome coronavirus 2 infection

We report the case of a man in his early 70s with idiopathic acquired haemophilia A and persistent high-titre type II inhibitors on immunosuppressive treatment to eradicate the inhibitor. As complications, he had a nosocomial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, which caused severe pneumonia and an explosive inflammatory reaction that required tocilizumab and remdesivir treatment, and a high-risk retroperitoneal haematoma. Recombinant porcine factor VIII, susoctocog alfa, was requested from the Pharmacy Service in view of the extreme risk of thromboembolism resulting from the concomitant inflammatory storm caused by SARS-CoV-2. Improvement in the SARS-CoV-2 infection made it possible to complete the immunosuppressive treatment with rituximab. The patient was discharged with mycophenolate mofetil as immunosuppressive treatment after 89 days in hospital and 22 days of treatment with susoctocog alfa. His SARS-CoV-2 infection resolved and the haematoma evolved favourably.

The Possible Non-Mutational Causes of FVIII Deficiency: Non-Coding RNAs and Acquired Hemophilia A

Hemophilia type A (HA) is the most common type of blood coagulation disorder. While the vast majority of cases are inherited and caused by mutations in the F8 gene, recent data raises new questions regarding the non-heritability of this disease, as well as how other molecular mechanisms might lead to the development of HA or increase the severity of the disease. Some data suggest that miRNAs may affect the severity of HA, but for some patients, miRNA-based interference might cause HA, in the absence of an F8 mutation. A mechanism in HA installation that is also worth investigating and which could be identified in the future is the epigenetic silencing of the F8 gene that might be only temporarily. Acquired HA is increasingly reported and as more cases are identified, the description of the disease might become challenging, as cases without FVIII autoantibodies might be identified.

Hemostatic therapy as a management strategy for acquired hemophilia: what does the future hold?

Introduction: Acquired hemophilia A (AHA) is a rare autoimmune disease caused by autoantibodies that bind and inactivate factor VIII (FVIII), predisposing to a potentially life-threatening bleeding.Areas covered: The main epidemiological, clinical, laboratory and therapeutic features of AHA are critically discussed. In particular, we focus on the hemostatic management of AHA patients analyzing the currently available treatment options and showing the latest data on the innovative hemostatic agents still under investigation. Authors searched the Medline and PubMed electronic databases for publication on AHA in the last twenty years.Expert opinion: While a rapid recognition of suspected cases of AHA is essential to make a correct diagnosis and appropriately and timely treat the hemorrhagic manifestations, the multidisciplinary approach to this challenging, rare and life-threatening bleeding disorder is of equal importance to improve patients' outcome. Although promising, the safety and efficacy of the clinical use of emicizumab in AHA needs to be validated by trials including an adequate number of patients, before registering the drug also for this indication.

Genetic causes of haemophilia in women and girls

Women and girls reported as "haemophilic females" may have complex genetic causes for their haemophilia phenotype. In addition, women and girls may have excessive bleeding requiring treatment simply because they are heterozygous for haemophilia alleles. While severe and moderate haemophilia are rare in females, 16% of patients with mild haemophilia A and almost one-quarter of those with mild haemophilia B seen in U.S. haemophilia treatment centres are women and girls. A phenotypic female with a low level of factor VIII or factor IX may be classified into one of the following categories of causality: homozygosity (two identical haemophilia alleles), compound heterozygosity (two different haemophilia alleles), hemizygosity (one haemophilia allele and no normal allele), heterozygosity (one haemophilia allele and one normal allele), genetic causes other than haemophilia and non-genetic causes. Studies required for classification may include coagulation parameters, F8 or F9 sequencing, F8 inversion testing, multiplex ligation-dependent probe amplification, karyotyping and X chromosome inactivation studies performed on the patient and parents. Women and girls who are homozygous, compound heterozygous or hemizygous clearly have haemophilia, as they do not have a normal allele. Heterozygous women and girls with factor levels below the haemostatic range also meet the definitions used for haemophilia treatment.

Bleeding and response to hemostatic therapy in acquired hemophilia A: results from the GTH-AH 01/2010 study

Acquired hemophilia A (AHA) is due to autoantibodies against coagulation factor VIII (FVIII) and most often presents with unexpected bleeding. In contrast to congenital hemophilia, the patient's residual FVIII activity does not seem to correlate with the risk of bleeding as suggested from previous studies. Risk factors for bleeding have not been described. We used data from the prospective GTH-AH 01/2010 study to assess the risk of bleeding and the efficacy of hemostatic therapy. FVIII activity was measured at baseline and weekly thereafter. Bleeding events were assessed by treating physicians. A total of 289 bleeds were recorded in 102 patients. There were 141 new bleeds observed starting after day 1 in 59% of the patients, with a mean rate of 0.13 bleed per patient-week in weeks 1 to 12, or 0.27 bleed per patient-week before achieving partial remission. Weekly measured FVIII activity was significantly associated with the bleeding rate, but only achieving FVIII activity ≥50% abolished the risk of bleeding. A good World Health Organization performance status assessed at baseline (score 0 vs higher) was associated with a lower bleeding rate. Hemostatic treatment was reportedly effective in 96% of bleeds. Thus, the risk of new bleeds after a first diagnosis of AHA remains high until partial remission is achieved, and weekly measured FVIII activity may aid in assessing the individual risk of bleeding. These results will help to define future strategies for prophylaxis of bleeding in AHA.

Acquired hemophilia A that required surgical hemostasis of hematomas occupying oral cavity: a case report

Background

Acquired hemophilia A is a rare coagulopathy caused by inhibitors of blood coagulation factor VIII. Patients with acquired hemophilia A have a higher mortality risk (5–10%) than those with congenital hemophilia. Moreover, there is no established evidence of management recommended for patients with acquired hemophilia A. Previous studies have reported the presence of hematomas in the oral cavities of patients with acquired hemophilia A, which were treated conservatively. Here, we describe the case of a patient with acquired hemophilia A, where emergency surgical hemostasis was required for large intraoral hematomas.

Case presentation

A 65-year-old Japanese man was referred to our hospital with a chief complaint of bleeding from large intraoral hematomas. On examination, he could not close his mouth because of the hematomas, which were bleeding spontaneously. Computed tomography angiography revealed no evidence of arteriovenous malformation, and blood test results showed that the activated partial thromboplastin time was elevated beyond the normal limit. To avoid a life-threatening hemorrhage from hematomas, emergency surgical hemostasis was performed with nasotracheal intubation using fiberoptic bronchoscopy. Hemostasis was successfully performed, as the hematomas were carefully removed. Moreover, the clinical course was successfully completed using intravenously administered activated prothrombin complex concentrate for hemostasis after operation.

Conclusions

Acquired hemophilia A can cause a life-threatening hemorrhage without predictive factors. Intraoral hematoma may cause airway obstruction. There is no consensus regarding the management of hemorrhage in patients with acquired hemophilia A. As shown here, exophytic hematomas in the oral cavity can be safely removed and nasotracheal intubation with fiberoptic bronchoscopy may be useful in patients with coagulopathy disease.

Two case reports of acquired haemophilia A as complications of alemtuzumab treatment for multiple sclerosis

Objective

To describe the case histories of two patients who developed acquired haemophilia A following treatment with alemtuzumab for multiple sclerosis.

Results

Two patients, a 48-year-old woman and a 31-year-old woman, developed acquired haemophilia A 21 months after their second doses of alemtuzumab. Both presented with spontaneous bruising, and the second case reported menorrhagia. One patient required treatment to control bleeding. Both patients responded to treatment with prednisolone and cyclophosphamide to eliminate the inhibitor.

Conclusions

Acquired haemophilia A is a rare complication following treatment with alemtuzumab. Activated partial thromboplastin time and prothrombin time should be performed in cases of abnormal bleeding in which the platelet count is normal, to facilitate timely diagnosis and prevention of major bleeding complications.

Bullous pemphigoid is a common associated disorder with acquired haemophilia A

Although the estimated incidence of acquired haemophilia A (AHA) in Singapore is similar to those reported in the literature, we have observed differences in the frequency of their associated diseases, particularly bullous pemphigoid (BP). We investigated the actual incidence of BP among our AHA cohort, their clinical characteristics and treatment outcomes. 6 out of 37 (16%) patients with AHA had BP, making it the most common underlying disorder in our cohort. The median age at diagnosis of AHA was 76 years old with a female preponderance. Most patients had their AHA diagnosed after BP with the median time between BP to AHA diagnosis being 107.5 days. Initial haemostasis was achieved, and factor VIII inhibitor was eliminated in all patients with a median time of disappearance being 52 days. Two patients had recurrence of their factor VIII inhibitor during the tapering of their immunosuppression. There was no relationship between the relapse of BP and AHA. This study suggests that BP is a common association with AHA. These patients respond well to bypassing agent and immunosuppression. However, they have a higher recurrence of factor VIII inhibitor and should be monitored closely for relapse during the tapering period of their immunosuppression.

Six cases of autoimmune acquired coagulation factor VIII deficiency: Single center experience in Japan

We report six cases of autoimmune acquired coagulation factor VIII deficiency, which is a rare bleeding disorder. It is an autoimmune disease, however, there are various causes. We experienced cases with malignancy, co-exist with another autoimmune disease, pregnancy, and unknown epidemiology with repeated bleeding episode. All patients were controlled the acute bleeding phase and they have been under treatment with immunosuppression.

Cross-reacting recombinant porcine FVIII inhibitors in patients with acquired haemophilia A

INTRODUCTION

Acquired haemophilia A (AHA) is a rare bleeding disorder caused by the development of autoantibodies to endogenous human factor VIII (hFVIII). If treatment of bleeding is required, one option is recombinant porcine FVIII (rpFVIII). Cross-reactivity between factor VIII inhibitors and rpFVIII has previously been described.

AIM

The aim of this study was to retrospectively assess the incidence of cross-reacting anti-porcine inhibitors in patients diagnosed with AHA in two UK centres.

METHODS

The plasma of fifty-one patients diagnosed with AHA via reduced FVIII:C and positive FVIII inhibitor titre as detected with a Nijmegen-Bethesda assay (NBA) was also tested by a porcine Bethesda assay (PBA). The NBA was modified by replacement of human FVIII with rpFVIII in the PBA, with determination of residual FVIII by one-stage clotting assay.

RESULTS

The median FVIII inhibitor titre by NBA was 22.8 BU/mL (range: 0.8-1000 BU/mL). 37% of samples exhibited linear, type 1 kinetics in the NBA. Negative PBA was observed in 26 patients, and 25 were positive (median PBA: 3.5 BU/mL; range: 0.8-120 BU/mL). Type 1 kinetics were observed in 40% of PBA-positive patients. At NBA tires of greater than 100 BU/mL, the positive predictive value for the presence of porcine cross-reactivity was 100%. At NBA below 5 BU/mL, the negative predictive value for the presence of porcine cross-reactivity was 71%.

CONCLUSION

Cross-reactivity between FVIII inhibitors and rpFVIII was observed in 49% of patients. The presence of inhibitors to rpFVIII may influence the treatment choice for patients with acquired haemophilia A.

Surgery-associated acquired hemophilia A: a report of 2 cases and review of literature

BACKGROUND

Acquired Hemophilia A (AHA) is a rare bleeding diathesis in patients with no previous personal or family bleeding history. The diagnosis of this disease often delays due to unfamiliarity of physicians with it, which leads to its high mortality rate.

CASE PRESENTATION

Two cases (one 12 years old female and another 18 years old male) were admitted for right upper abdominal mass and right upper abdominal pain respectively at different times. Pre-operative diagnosis of both cases was congenital choledochal cyst. They suffered continuous gastrointestinal bleeding (hematemesis and melena) with reduced hemoglobin to 54 g/L and 60 g/L after Roux-en-Y anastomosis respectively. To investigate the exact bleeding site, Digital subtraction angiography (DSA) of case 1 showed contrast overflow at small branch of proper hepatic artery but had unremarkable result for case 2, whereas gastroscopy of both cases showed unremarkable results. Multiple surgeries were also performed for hemostatic purpose but each time no active bleeding site was found. Finally, hematologists consultation was mandated in both cases and they were diagnosed as acquired haemophilia A. However, unfortunately case 1 patient could not survive because of sever hemorrhage and infection while Case 2 of 18 years old male survived after proper haemophilia treatment catalog.

CONCLUSION

Awareness about surgery associated acquired haemophilia A (SAHA) can facilitate quick diagnosis and lifesaving management because the mortality rate in SAHA is high due to lake of knowledge or late recognition of the disease. Bleeding always occurs at surgical sites and it can occur immediately within few hours after surgery in some cases. Hemorrhage may be severe or even life threatening and it presents a special challenge for diagnosis and treatment in a patient who has just undergone a surgical procedure. The treatment strategies for AHA include resumption of hemostasis with either recombinant porcine factor VIII (rpFVIII) or bypassing agents and immunosuppressive therapy to suppress the production of the factor VIII inhibitor.

Reduced-intensity, risk factor-stratified immunosuppression for acquired hemophilia A: single-center observational study

Immunosuppressive therapy (IST) is administered to patients with acquired hemophilia A (AHA) to eradicate autoantibodies against coagulation factor VIII (FVIII). Data from registries previously demonstrated that IST is often complicated by adverse events, in particular infections. This pilot study was set out to assess the feasibility of reduced-intensity, risk factor–stratified IST. We followed a single-center consecutive cohort of twenty-five patients with AHA receiving IST according to a new institutional treatment standard. Based on results from a previous study, GTH-AH 01/2020, patients were stratified into “poor risk” (FVIII < 1 IU/dl or inhibitor ≥ 20 Bethesda units (BU)/ml) or “good risk” (FVIII ≥ 1 IU/dl and inhibitor < 20 BU/ml). Outcomes were compared between the current cohort and the GTH registry as a historic control (n = 102). Baseline characteristics of the cohort were not different from the historic control. Partial remission, defined as FVIII recovered to > 50 IU/dl, was achieved by 68% of patients after a median time of 112 days, which was lower and significantly later than in the historic control (hazard ratio: 1.8, 95% confidence interval 1.2–2.8). Complete remission, overall survival, and frequency of fatal infections were not different. Grade 3 and 4 infections were more frequent. The impact of risk factors that was observed in the historic cohort was no longer apparent, as partial and complete remission and overall survival were similar in “good risk” and “poor risk” patients. In conclusion, reduced-intensity, risk factor–stratified IST is feasible in AHA but did not decrease the risk of infections and mortality in this cohort.

Identifying risk factors and optimizing standard of care for patients with acquired haemophilia A: Results from a Czech patient cohort

INTRODUCTION

Acquired haemophilia A (AHA) is a rare autoimmune disorder, characterized by bleeds of varying severity caused by autoantibodies against factor VIII (FVIII).

AIM

Identify risk factors associated with AHA-related deaths/relapses and assess the effect of increased corticosteroid doses.

METHODS

AHA patients treated across two specialist centres in the Czech Republic, generally receiving first-line haemostatic therapy with rFVIIa and immunosuppression with corticosteroids/cyclophosphamide, were included. We analysed the association between early death (within 8 weeks of diagnosis [considered disease-related]) and age, malignancy, FVIII levels and bleeding severity. Risk factors associated with reduced 2-year survival and relapse incidence, and the effect of increased corticosteroid doses on early death and remission were also assessed.

RESULTS

The demographics of the described cohort (n = 66) were similar to other AHA registries. Early death occurred in 20% of cases. Unlike age and malignancy, FVIII levels <1% and severe bleeding were associated significantly with early death (P = .010 and P = .046, respectively). Patients with underlying malignancy or requiring continued haemostatic therapy exhibited significantly decreased 2-year survival compared with those without these risk factors (P = .007 and P = .006, respectively). Patients with an underlying autoimmune disease relapsed significantly more than those without (P = .015). Higher corticosteroid doses were associated with a significantly increased incidence of early deaths (P < .001), but also with early remission (P < .001).

CONCLUSION

Based on this rather large patient cohort, we were able to evaluate the significance of several risk factors associated with treatment outcomes in AHA and the effect of initial treatment with corticosteroids on survival and time to remission.

International recommendations on the diagnosis and treatment of acquired hemophilia A

Acquired hemophilia A (AHA), a rare bleeding disorder caused by neutralizing autoantibodies against coagulation factor VIII (FVIII), occurs in both men and women without a previous history of bleeding. Patients typically present with an isolated prolonged activated partial thromboplastin time due to FVIII deficiency. Neutralizing antibodies (inhibitors) are detected using the Nijmegen-modified Bethesda assay. Approximately 10% of patients do not present with bleeding and, therefore, a prolonged activated partial thromboplastin time should never be ignored prior to invasive procedures. Control of acute bleeding and prevention of injuries that may provoke bleeding are top priorities in patients with AHA. We recommend treatment with bypassing agents, including recombinant activated factor VII, activated prothrombin complex concentrate, or recombinant porcine FVIII in bleeding patients. Autoantibody eradication can be achieved with immunosuppressive therapy, including corticosteroids, cyclophosphamide and rituximab, or combinations thereof. The median time to remission is 5 weeks, with considerable interindividual variation. FVIII activity at presentation, inhibitor titer and autoantibody isotype are prognostic markers for remission and survival. Comparative clinical studies to support treatment recommendations for AHA do not exist; therefore, we provide practical consensus guidance based on recent registry findings and the authors' clinical experience in treating patients with AHA.

Acquired Hemophilia A: A Potentially Fatal Bleeding Disorder

Acquired hemophilia A (AHA) is a rare autoimmune hematological disorder that has an incidence of about 1.5 cases per million people per year. It occurs in the elderly with the median age of 75 years, and most of the cases are idiopathic. It occurs due to the development of factor VIII inhibitor, which is an autoantibody against factor VIII leading to potentially life-threatening bleeding episodes. The diagnosis of AHA is often delayed and challenging. We report a case of an 86-year-old male who initially presented with signs and symptoms of a stroke. He was found to have oral mucosal bleeding and swelling of the floor of the mouth. He later developed epistaxis, hematuria, and melena. He had an isolated elevation of activated partial thromboplastin time (APTT) with very high levels of factor VIII inhibitor (1152 Bethesda units) and very low levels of Factor VIII (<1%). He was managed with supportive transfusion, bypass agents, and immunosuppressive therapy. AHA is a rare autoimmune bleeding disorder and is more commonly seen in the elderly population. Bleeding in AHA is usually sudden and sometimes life-threatening. Hence early hemostasis with bypassing agents and treatment with immunosuppressive agents should be initiated. Due to the rarity of the disorder, it is crucial to report AHA cases to create awareness and increase the index of suspicion of the clinicians for early diagnosis and treatment to prevent morbidity and mortality.

Management of rare acquired bleeding disorders

Autoantibodies toward clotting factors may develop in people suffering from autoimmune or neoplastic diseases, after drug intake or even in subjects without apparent conditions. They are more commonly directed against factor VIII (FVIII) or von Willebrand factor leading to acquired hemophilia A or acquired von Willebrand syndrome, respectively. Rarely, autoantibodies develop against other clotting factors, such as fibrinogen, FII, FV, FVII, FX, FXI, and FXIII. The clinical picture of an acquired bleeding disorder includes a wide spectrum of clinical manifestations ranging from minimal or no bleeding to life-threatening events. Patients with no previous personal or family history of bleeding may have sudden-onset hemorrhagic manifestations, sometimes fatal, especially if an early diagnosis is not made. On the other hand, some patients may not have hemorrhagic symptoms at onset, and their diagnosis can therefore be delayed. The laboratory diagnostic assessment is performed by screening coagulation tests followed by specific factor-level measurement and inhibitor-titrating assays. An early diagnosis of acquired coagulopathies is mandatory for starting the appropriate treatment aimed at both controlling the acute bleeding episode mainly using the bypassing agents, and eradicating the anticlotting factor autoantibody, using immunosuppressive treatment. Therefore, prompt intervention by an expert and a specialized center is needed for immediate recognition and treatment of the disease.

Acquired Factor VII deficiency - a rare but important consideration

INTRODUCTION

Isolated acquired Factor VII deficiency is a rare coagulation disorder which is independent of vitamin K deficiency. The exact pathophysiological basis of this condition is unclear. We present a series of cases highlighting different clinical scenarios where this condition was encountered.

CASE SERIES

The first case presented with intra-abdominal sepsis. The second was a patient admitted with acute kidney injury and subsequently diagnosed with myeloma. The final case presented with microangiopathic haemolytic anaemia and was suspected of having atypical Haemolytic Uraemic Syndrome. In each case, there was no family or personal history of a bleeding disorder. Follow-up Factor VII levels after recovery from illness was normal in all three cases.

CONCLUSION

Acquired Factor VII deficiency is an uncommon but important finding which should be considered in the general medical setting when an isolated prolonged prothrombin time is detected.

Involvement of antifactor VIII autoantibodies specificity in the outcome of inhibitor eradication therapies in acquired hemophilia a patients

: We hypothesized that inhibitor specificity may predict the outcome of antifactor VIII autoantibodies eradication treatment in acquired hemophilia A. Our objective was to analyze the association between factor VIII domains recognized by inhibitors and outcome of the immunosuppressive therapies (ISTs) in a prospective, observational study. 16 patients were recruited. Inhibitor specificities were assessed at diagnosis and throughout the study. Their association with IST outcome was addressed. First-line IST succeeded in 56% of patients. Inhibitors reacted mainly with light chain domains (69%) and/or the A2 domain (44%). 31% inhibitors recognized more than one domain. Significantly, the number of patients whose inhibitors recognized the light chain was significantly higher in the group of those who did not reach complete remission after first line IST when compared with those who did [6/7 (85.7%) vs. 4/9 (44.4%), P < 0.05]. Therefore, inhibitor specificity could predict the success of IST in acquired hemophilia A.

Relapse pattern and long-term outcomes in subjects with acquired haemophilia A

INTRODUCTION

Acquired haemophilia A (AHA) is a rare autoimmune bleeding disorder caused by neutralizing antibodies against factor VIII (FVIII). Despite significant initial morbidity and mortality, most patients achieve remission with immunosuppressive therapy.

AIM

Long-term follow-up data from the Quebec Reference Centre for Inhibitors (QRCI) were analysed to identify factors predictive of AHA relapse and the influence of relapse on survival.

METHODS

Criteria used to define AHA were levels of FVIII <0.3 IU/mL and FVIII inhibitor titres ≥0.6 Bethesda Units (BU). Complete remission was defined as FVIII >0.5 IU/mL and/or FVIII inhibitor titres <0.6 BU while not on immunosuppression.

RESULTS

Between 2000 and 2012, 111 subjects met the inclusion criteria and were followed for a median of 25.6 months. Ninety per cent of them reached remission on immunosuppression in a median time of 45 days. Fourteen patients presented one or more relapses in a median time of 13.4 months. Most relapse episodes were successfully treated. Associated lymphoproliferative syndromes (LPS) were predictive of relapse, whereas FVIII activity and inhibitor titres at initial diagnosis or immunosuppressive regimens were not. The overall survival (OS) was the same, with or without relapse.

CONCLUSION

Among the recognized potential risk factors for relapse, only LPS was statistically significant. The long-term follow-up of our patients also showed that late or multiple relapses may occur, but that relapse is not associated with a worse OS. Thus, long-term follow-up is important for optimal management of AHA.

Acquired Hemophilia A Presenting as Intramuscular Hematoma

Acquired hemophilia A poses a clinical and diagnostic challenge. Although rare, it is still the most common acquired factor deficiency. We present a case of acquired hemophilia A diagnosed in a 71-year-old female who presented with a right thigh hematoma of acute onset. The diagnosis was established based on the coagulation profile along with factor VIII levels, mixing studies, and inhibitor levels. The patient received multiple lines of therapy including steroids, factor VIIa, Obizur (porcine-derived recombinant factor VIII), followed by multiple cycles of chemotherapy including cyclophosphamide and rituximab.

[Analysis of clinical efficacy of recombinant activated factor Ⅶ on bleeding in patients with hematologic disorders]

目的

研究重组人凝血因子Ⅶa（rFⅦa）治疗血液病患者出血的疗效。

方法

回顾性分析rFⅦa治疗31例血液病患者共38次出血的临床资料。

结果

rFⅦa治疗获得性血友病A（AHA）/血友病伴抑制物、急性早幼粒细胞白血病（APL）、急性非APL白血病患者出血的总体有效率分别为90%（9/10）、71.4%（5/7）、60.0%（3/5），高于造血干细胞移植后患者（30.8%）；rFⅦa治疗评分为2分出血的有效率（100.0%）高于3分（66.7%）及4分（51.6%）出血；5例次颅内出血中2例次（25.0%）有效；9例次血尿中6例次（66.7%）有效；12例次消化道出血中5例次（41.7%）有效。3例次关节及肌肉出血的疗效均为极好，5例次出血部位为皮肤、鼻黏膜、咽部及齿龈，疗效均为极好；移植后患者在出血评分为4分时，高剂量以及多次使用rFⅦa并不一定能取得好的疗效。AHA/血友病伴抑制物及急性白血病患者合并的出血，在评分为4分时，使用低剂量rFⅦa能取得好的疗效，但最低用药剂量（22.5 µg/kg）的疗效差。

结论

rFⅦa的止血疗效受疾病类型、出血部位以及严重程度等多个因素的影响。rFⅦa对AHA/血友病伴抑制物以及急性白血病患者的出血具有较好的疗效，但对移植后患者的出血疗效欠佳。出血早期使用rFⅦa对于疗效至关重要。在止血治疗的同时，应积极治疗基础疾病。

A decade-long clinical experience on the prophylactic use of activated prothrombin complex concentrate in acquired haemophilia A: a case series from a tertiary care centre

: In acquired haemophilia A (AHA), risk for recurrent bleeding exists until the inhibitor is detectable. Thus, patients with persisting inhibitor may benefit from prophylaxis with activated prothrombin complex concentrate (aPCC). Potential thromboembolic complications and cost are also factors to consider. Today, no high level evidence or clear recommendations are available on aPCC prophylaxis in AHA. Recently, a small prospective study demonstrated a favourable outcome with short-term, daily administered aPCC infusion. Here we report a retrospective case series of 19 patients with AHA to demonstrate our practice on aPCC prophylaxis. In our practice, clinical bleeding tendency guided our decision on the initiation of aPCC prophylaxis. In patients with serious bleeding tendency, aPCC infusion was prolonged beyond bleeding resolution in a twice-weekly or thrice-weekly regimen. Serious bleeding phenotype included a single episode of life-threatening bleeding or recurrent, severe haemorrhages. Patients who did not present such events were treated on-demand. The preventive dose of aPCC was equal with the lowest effective therapeutic dose. Prophylaxis was continued until the inhibitor disappeared. Eleven patients received aPCC prophylaxis. In nine cases, prophylaxis lasted beyond two months. No severe bleeding developed spontaneously and no thromboembolic complication occurred in the median 16 weeks (interquartile range 9-34) duration of prophylaxis. Eight patients of the nonprophylaxis group did not present any severe haemorrhage. According to our experience, we consider prophylaxis with aPCC effective and well tolerated for patients with AHA and serious bleeding tendency, until the acquired inhibitor persists.

Novel assays in the coagulation laboratory: a clinical and laboratory perspective

The ability to monitor Factor VIII (FVIII) and Factor IX (FIX) levels is integral to the clinical management of hemophilia A and B patients, respectively. Factor activity levels are checked during regular follow-up, post-infusion of factor concentrates, during pre- and post-operative assessments, and when the presence of an inhibitor is suspected. However, the ability to accurately and reproducibly measure factor activity levels with standard coagulation assays has been challenging due to the emergence of recombinant factor concentrates with extended half-lives. Similarly, special considerations must be given to the type of inhibitor assay used in patients with acquired hemophilia receiving recombinant porcine FVIII replacement. Alternative approaches to achieve hemostasis with clotting factor mimetics and interference of endogenous anticoagulants lack standardized assays for monitoring hemostatic efficacy. Laboratory assays measuring dynamic clotting parameters such as thrombin generation or whole blood viscoelasticity may provide a way forward, but have yet to enter routine clinical use. This review highlights the role of specialized coagulation assays in an era where multiple new hemostatic therapeutics for hemophilia are available, and underscores the need for clear communication between bedside and laboratory clinicians.