Inhibitors to clotting factors

Endothelium, Platelets, and Coagulation Factors as the Three Vital Components for Diagnosing Bleeding Disorders: A Simplified Perspective with Clinical Relevance

Bleeding disorders are a major group of hematological disorders, which are highly prevalent in the world. Excessive bleeding can result in serious consequences including hypoperfusion and cardiac arrest. The body has its selfmechanism to control excessive bleeding which is termed hemostasis. Hemostasis is achieved in two major steps, the formation of the primary and secondary hemostatic plugs. Endothelium, platelets, and coagulation factors are three components involved in hemostasis. Endothelium and platelets have a major role in forming the primary hemostatic plug. Consequently, the first step in investigating a bleeding disorder is platelet count. Despite normal platelet count, abnormality in the primary hemostatic plug may arise due to functional defects of the platelets including adhesion, activation, and aggregation. Von Willebrand disease (VWD) is an endothelial defect and the most prevalent inherited defect in coagulation. Abnormalities in the secondary hemostatic plug are largely due to coagulation factor deficiencies, and, to a lesser extent, the presence of inhibitors. Techniques involving viscoelastics have been aiding in rapid diagnosis and are useful in point-of-care testing. This article discusses the investigation of bleeding disorders from the perspective of the endothelium, platelet, and coagulation factor physiology. These three components should be properly investigated to achieve the definitive diagnosis of bleeding disorders.

Complement and Coagulation System Crosstalk in Synaptic and Neural Conduction in the Central and Peripheral Nervous Systems

Complement and coagulation are both key systems that defend the body from harm. They share multiple features and are similarly activated. They each play individual roles in the systemic circulation in physiology and pathophysiology, with significant crosstalk between them. Components from both systems are mapped to important structures in the central nervous system (CNS) and peripheral nervous system (PNS). Complement and coagulation participate in critical functions in neuronal development and synaptic plasticity. During pathophysiological states, complement and coagulation factors are upregulated and can modulate synaptic transmission and neuronal conduction. This review summarizes the current evidence regarding the roles of the complement system and the coagulation cascade in the CNS and PNS. Possible crosstalk between the two systems regarding neuroinflammatory-related effects on synaptic transmission and neuronal conduction is explored. Novel treatment based on the modulation of crosstalk between complement and coagulation may perhaps help to alleviate neuroinflammatory effects in diseased states of the CNS and PNS.

Coagulopathy and its associated factors among patients with a bleeding diathesis at the University of Gondar Specialized Referral Hospital, Northwest Ethiopia

Background

Coagulopathy is the major cause of mortality and morbidity throughout the world. Globally, about 26–45% of healthy people have a history of bleeding symptoms, which may be a result of thrombocytopenia, factor deficiency, or pathological inhibitory.

Objective

To assess coagulopathy and its associated factors among patients with bleeding diathesis at the University of Gondar Specialized Referral Hospital from January to May 2020.

Method

A cross-sectional study was conducted on 384 study participants with bleeding diathesis recruited by using a convenient sampling technique. Socio-demographic and clinical characteristics were collected by using questioners. Then 6 ml venous blood was collected with a needle and syringe method. About 3 ml blood was transferred to EDTA test tube for platelet count and 2.7 ml blood was transferred to a test tube containing 0.3 ml of 3.2% sodium citrated anticoagulant for coagulation test. For those study participants with prolonged coagulation tests, a mixing test was done. Blood film and stool examination were also done for malaria and intestinal parasite identification, respectively. The data were entered into EPI-Info version 3.5.3 and then transferred to SPSS version-20 for analysis. Descriptive statistics were summarized as percentages, means, and standard deviations. Bivariate and multivariate logistic regression was used to identify the associated factors, and a P-value less than 0.05 was considered statistically significant.

Results

In this study, the prevalence of coagulopathy was 253/384 (65.9%; 95% CI: 61.16, 70.64). From them, 21.3% (54/253), 51.4% (130/253), and 27.3% (69/253) had only thrombocytopenia, only prolonged coagulation test, and mixed abnormality, respectively. Among participants with prolonged coagulation time, the prevalence of factor deficiency was 21.1% (42/199). Cardiac disease (AOR = 4.80; 95% CI: 2.65, 23.1), and other chronic diseases (AOR = 8.1; 95% CI: 1.84, 35.58) were significantly associated with coagulopathy.

Conclusion

In this study, coagulopathy due to inhibitory was a public health problem. The participants with cardiac and other chronic diseases were at high risk for coagulopathy. Therefore, mixing tests could be done for all prolonged coagulation tests and it could be considered as a routine laboratory test.

Severity of Anaemia Has Corresponding Effects on Coagulation Parameters of Sickle Cell Disease Patients

Sickle cell disease (SCD) is an inherited condition characterized by chronic haemolytic anaemia. SCD is associated with moderate to severe anaemia, hypercoagulable state and inconsistent platelet count and function. However, studies have yielded conflicting results with regards to the effect of anaemia on coagulation in SCD. The purpose of this study was to determine the effect of anaemia severity on selected coagulation parameters of SCD patients. Four millilitres of venous blood samples were taken from the participants (SCD and non-SCD patients) and used for analysis of full blood count and coagulation parameters. Data was analysed using SPSS version-16. From the results, it was seen that individuals with SCD had a prolonged mean PT, APTT and high platelet count compared to the controls. There was also significant difference in the mean PT (p = 0.039), APTT (p = 0.041) and platelet count (p = 0.010) in HbSS participants with severe anaemia. Mean APTT also showed significant difference (p = 0.044) with severe anaemia in HbSC participants. It can be concluded that SCD patients have prolonged PT, APTT and increased platelet count which might predispose them to bleeding episodes and thrombocytosis. Significant difference was also seen between severity of anaemia and mean PT, APTT and platelet count in HbSS individuals.

Immune Tolerance Therapy in Patients with Acquired Hemophilia

Acquired hemophilia is a rare disorder with an estimated annual incidence of 0.2-1 cases per million individuals. The etiology of the disorder remains obscure, although approximately half of all cases are associated with other underlying conditions. In acquired hemophilia, the severe hemorrhagic diathesis is caused by the development of autoantibodies directed against a clotting factor, most commonly factor VIII. These autoantibodies inhibit normal coagulation and lead to bleeding complications, which can be life-threatening in a high percentage of cases. Prompt diagnosis and appropriate management of the disorder enable effective control; the short- and long-term aims of therapy are to terminate the acute bleed and eliminate or reduce the inhibitor, respectively. Immune tolerance therapy has been shown to successfully eradicate or suppress inhibitors in patients with congenital hemophilia A and may be applicable to patients with acquired hemophilia. Here we present preliminary data on the use of immune tolerance therapy in patients with acquired hemophilia and discuss possible treatment strategies.

Rare case of acquired haemophilia and lupus anticoagulant

Acquired haemophilia or factor VIII (FVIII) deficiency, caused by FVIII inhibitor antibodies, is a very rare condition that commonly results in severe haemorrhagic complications. We report a case of acquired haemophilia presenting with multiple bluish patches affecting face, neck, upper & lower limbs, history of gum bleeding and left knee haemarthrosis. The patient was found to have acquired FVIII inhibitor and lupus anticoagulant (LAC). The simultaneous presence of LAC and FVIII inhibitor is exceedingly rare. The differentiation between these two conditions is crucial, because both result in a prolongation of the activated partial thromboplastin time test, which does not correct when mixed with the plasma of a normal control; however, the clinical manifestations range from thrombosis in the presence of LAC to massive haemorrhage with FVIII inhibitors.

Approach to the treatment, characterization and diagnosis of an acquired auto-antibody directed against factors prothrombin, factor X and factor IX: a case report and review of the literature

Bleeding disorders secondary to acquired non-inhibitory antibodies directed against vitamin K-dependent coagulation proteins are rare. In this report, the authors describe a patient with a low grade lymphoma who presented with a fatal acquired bleeding manifestation and abnormal hemostatic studies resulting from deficiencies in both prothrombin and factor X. Patient plasma samples were collected and studied for the presence of an acquired inhibitor. Levels of plasma coagulation proteins were measured using immunoassay. Patient anti-prothrombin immunoglobulin G was isolated and binding to prothrombin, prothrombin F1.2, factors IX and X was evaluated using immunoblots and competition immunoassay. Prolongation in the prothrombin time and activated partial thromboplastin time suggested a factor deficiency in the common pathway of coagulation. Functional and antigenic levels of both prothrombin and factor X were decreased. An IgG subtype-4 antibody was isolated from patient plasma using affinity chromatography on prothrombin-sepharose. This antibody was found to bind to a common metal-ion-dependent conformational epitope found on the γ-carboxyglutamic acid (Gla) domain of prothrombin, factor X and factor IX. This report represents the first description of an acquired bleeding disorder resulting from a unique cross-reactive auto-antibody against a common metal-ion-dependent antigenic structure on the Gla-domain of the vitamin K-dependent proteins.

Cost and effectiveness of treatments for mild-to-moderate bleeding episodes in haemophilia patients with inhibitors in Korea

First-line treatment for mild-to-moderate bleeding episodes in patients with haemophilia and inhibitors in Korea is currently activated prothrombin complex concentrate (aPCC) with recombinant activated factor VII (rFVIIa) as second-line therapy or as a last resort. The aim of this study was to estimate the cost and effectiveness of aPCC vs. rFVIIa for treating mild-to-moderate bleeds in inhibitor patients from the Korean reimbursement authorities' perspective. Clinical outcomes and resource utilization data (number of doses, average dose, number of outpatient visits, inpatient stays, ambulance transport and concomitant medications) were collected from an observational study involving four Korean paediatric haemophilia centres. Cost-effectiveness was modelled using a decision analysis approach and sensitivity analyses undertaken. rFVIIa was a more effective haemostatic therapy (87.1% efficacy in bleed resolution) than aPCC (64.0%). rFVIIa effected more rapid haemostasis, resolving bleeding in a mean of 6.6 h vs. 25.2 h for aPCC. Fewer rFVIIa doses were required per bleed vs. aPCC (means 1.7 and 2.3). Mean total direct medical costs from bleed initiation to cessation were estimated at Korean Won (KRW)12 460 thousand (US$12 311) for rFVIIa given as first-line therapy and KRW18 304 thousand (US$18 085) for aPCC given as first-line therapy. Sensitivity analyses confirmed the cost-effectiveness of rFVIIa vs. aPCC given as first-line therapy. In Korea, use of rFVIIa as first-line therapy for treatment of mild-to-moderate bleeding episodes in inhibitor patients is both clinically effective and cost-effective compared with initial aPCC treatment. rFVIIa should be considered as the first-line treatment for mild-to-moderate bleeding episodes in patients with haemophilia and inhibitors in Korea.

Rituximab for adolescents with haemophilia and high titre inhibitors

Neutralizing alloantibodies (inhibitors) to factor VIII or factor IX develop in approximately 25% of patients with haemophilia A and <3% of patients with haemophilia B treated with factor concentrate. Patients with high titre inhibitors, in whom immune tolerance therapy fails, have few treatment options. Targeted anti-B-cell therapy with rituximab (chimeric anti-CD20) has been useful in several antibody-mediated autoimmune states. Case reports of rituximab treatment in small numbers of haemophilia patients with inhibitors have been inconclusive. We describe three adolescent patients with severe haemophilia and inhibitors treated with four weekly doses of rituximab, 375 mg m(-2). Treatment with rituximab was effective in reducing the inhibitor titre in two of three patients. Rituximab may be beneficial for patients with severe haemophilia and inhibitors in whom standard therapies have failed, but larger prospective studies are required to determine safety, efficacy and predictors of success.

Presentation and Management of a Stage Ia Lung Cancer Patient With a Paraneoplastic Factor VIII Inhibitor

Acquired inhibitors to clotting factors most commonly involve factor VIII and are associated with autoimmune disease. Factor VIII inhibitors can cause severe spontaneous and iatrogenic bleeding that is difficult to manage. Factor VIII inhibitors are rarely associated with solid tumors and only three cases of adenocarcinoma of the lung have been reported. This report describes the multidisciplinary management of a factor VIII inhibitor-producing stage Ia lung adenocarcinoma that ultimately resulted in complete resectability.

Acquired Factor VIII Inhibitors in a Patient Associated with Neurosurgery: Case Report and Review of the Literature

OBJECTIVE AND IMPORTANCE

Acquired factor VIII inhibitors in patients without hemophilia is rare event characterized by severe bleeding as a result of antibody against factor VIII. We describe a patient who developed subcutaneous and epidural bleeding after the clipping of an unruptured aneurysm.

CLINICAL PRESENTATION

A 57-year-old man suddenly developed coagulopathy after undergoing a neurosurgical operation. Coagulation tests showed a prolongation of activated partial thromboplastin time and a marked reduction in factor VIII activity. Measurement of the factor VIII inhibitor level revealed 2 Bethesda units/ml.

INTERVENTION

The hematoma was removed surgically, and bleeding was controlled with recombinant factor VIII. The patients then received prednisolone (80 mg/d) and cyclosporine. The laboratory tests normalized within 8 weeks. In the 5 years since cessation of corticosteroids, the clinical and laboratory courses of the patient have been uneventful.

CONCLUSION

Autoimmune factor VIII inhibitors associated with a neurosurgical procedure are rare. Our case supports an association between surgery and the triggering of factor VIII inhibitors. This complication was probably the result of the surgical procedure or anesthetic agents or other drugs administrated during the perioperative period.

Coexistence of lupus anticoagulant and acquired haemophilia in a patient with monoclonal gammopathy of unknown significance

Acquired haemophilia or factor VIII (FVIII) deficiency, caused by FVIII inhibitor antibodies, is a very rare condition that commonly results in severe haemorrhagic complications. We report a case of acquired haemophilia presenting with a left calfnontraumatic haematoma. The patient was also found to have lupus anticoagulant (LAC). The simultaneous presence of LAC and FVIII inhibitor is exceedingly rare. The differentiation between these two conditions is crucial, because both result in a prolongation of the activated partial thromboplastin time test, which does not correct when mixed with the plasma of a normal control; however, the clinical manifestations range from thrombosis in the presence of LAC to massive haemorrhage with FVIII inhibitors.

Acquired Factor VIII autoantibody: four cases demonstrating the heterogenous nature of this condition and problems involved in diagnosis and treatment

The development of an autoantibody to human Factor VIII is rare and presents many problems for diagnosis and treatment. We have seen several cases at our institution recently with widely heterogenous clinical and laboratory presentations. A wide range of treatment modalities were used in these cases with no gold standard of treatment or widely accepted guidelines existing. This has prompted us to examine all cases of this condition presenting at Fremantle Hospital over the last decade. We describe four cases which demonstrate the heterogeneity of this condition and its treatment and review the recent literature on the subject.

Classification of the kinetics of factor VIII inhibitors in haemophilia A: plasma dilution studies are more discriminatory than time-course studies

Factor VIII inhibitors have previously been classified as type I or type II using complex experiments that study the time course of inactivation of factor VIII and the effect of varying the antibody concentration. Classification may be important to better understand inhibitor behaviour in vivo. To determine the most reliable method of classifying the kinetics of factor VIII inactivation, we studied 11 patients with haemophilia A, comprising five severe, three mild and three acquired cases, and compared the classification obtained from plasma dilution studies and time-course studies. The plasma dilution studies showed two distinctly different patterns: a steep slope with complete FVIII:C inactivation at high antibody concentrations for type I inhibitors and a FVIII:C plateau with incomplete inactivation for type II inhibitors. Six type I (four severe, one mild and one acquired) and two type II (one mild and one acquired) inhibitors were classified using either plasma samples or purified and concentrated IgG, while the remaining were undetermined owing to insufficient available plasma. In contrast, the time-course studies could not discriminate between these groups. We recommend that plasma dilution studies be used for the classification of in vitro kinetics of factor VIII inhibitors.

A literature review on the antiphospholipid syndrome and the effect on childbearing

OBJECTIVE

to review the literature on antiphospholipid antibodies and their significance to midwifery practice.

METHOD

databases using the keywords anticardiolipin antibodies, antiphospholipid antibodies, lupus antibodies, antiphospholipid syndrome, systemic lupus erythematosis, pregnancy loss, pre-eclampsia were searched, 548 articles were generated and 52 were used in the review.

FINDINGS

anticardiolipin antibodies are detrimental to successful pregnancy being implicated in failure of implantation, loss of the embryo and the fetus. There is also a risk of prematurity, intrauterine growth retardation and neonatal embolism. The risks to the mother are of pre-eclampsia and embolic complications. If diagnosed and treated early in pregnancy with low-dose aspirin and subcutaneous heparin the outlook for a successful pregnancy is much improved.

KEY CONCLUSIONS

much research remains to be undertaken. Researchers need to standardise their criteria so that findings are comparable and larger sample groups are necessary.

IMPLICATIONS FOR PRACTICE

antiphospholipid syndrome is an important disorder and a preventable cause of pregnancy loss. Midwives need to encourage women to persevere with therapy to preserve pregnancy and maybe prevent pre-eclampsia or thrombosis. When pregnancies are lost one of the hardest things is when the parents cannot understand why. Midwives need to understand the syndrome to collaborate with doctors in explaining it and supporting grieving parents.

Inhibitors against factor VIII in patients with cancer. Analysis of 41 patients

BACKGROUND

The spontaneous formation of neutralizing antibodies (inhibitors) to factor VIII (FVIII) in patients with cancer is a well known phenomenon. However, to the authors' knowledge there is lack of information in the literature with respect to the clinical course of these patients and the nature of the association between malignant tumors and acquired hemophilia.

METHODS

A retrospective study of 41 patients with cancer and acquired hemophilia was conducted. The patients were identified through a MEDLINE search between 1974-2000. All patients had detailed clinical and laboratory information available and descriptions of the course of the inhibitor in relation to cancer treatment. The patients were divided into two groups: responders and nonresponders. The stage of the tumor, inhibitor titer, FVIII level, and survival data were examined and compared between the two groups.

RESULTS

A total of 63 hemorrhagic episodes were reported in 25 patients with solid tumors and 16 patients with hematologic malignancies. The median inhibitor titer at the time of the diagnosis of acquired hemophilia was 14 Bethesda units (BU) (range, 1-435 BU). The complete response (CR) rate to treatment of the inhibitor was 70% and patients who achieved a CR were more likely to have early stage tumors (P = 0.0007) and a lower median inhibitor titer at the time of presentation compared with nonresponders (12 BU vs. 78 BU; P = 0.007). The overall survival was significantly higher in patients who achieved a CR compared with patients with a persistent inhibitor (75% vs. 17%; P = 0.0006).

CONCLUSIONS

Although it remains an uncommon occurrence, the development of inhibitors to FVIII should be considered as a cause of bleeding in some patients with malignant diseases. Because of the high response rate and the impact of this type of hemorrhage on cancer patients, efforts should be directed toward immunosuppression of the inhibitor in a fashion similar to that used in other patients with acquired hemophilia. To our knowledge the link between malignancy and the formation of antibodies to FVIII is unclear; however, it appears that treatment of cancer with chemotherapy or surgery may accelerate the eradication of the inhibitor in some patients. Long term prospective studies are needed to better assess the association between cancer and acquired hemophilia.

Acquired bleeding disorder in a patient with malignant lymphoma: antibody-mediated prothrombin deficiency

BACKGROUND

Bleeding manifestations secondary to acquired hemostatic abnormalities in cancer patients have been well described. Bleeding due to the development of hemostatic inhibitors is observed less frequently. In this report, the authors describe a patient with a low grade lymphoma who presented with an acquired bleeding disorder and abnormal hemostatic screening tests.

METHODS

Patient plasma samples were collected initially and during the course of treatment. Mixing studies and specific coagulation factor assays were performed to detect and confirm any deficiencies. Patient immunoglobulin G was isolated from plasma, and binding to prothrombin was demonstrated by immunoblot method and enzyme-linked immunosorbent assay (ELISA) techniques.

RESULTS

Initial prolongations in the prothombin time and the activated partial thromboplastin time suggested a factor deficiency in the common pathway of coagulation. Factor assays confirmed that the coagulation abnormality in this patient was the result of an acquired prothrombin (factor II) deficiency. This was confirmed by an immunoassay for prothrombin antigen. Further studies demonstrated the presence of a noninhibitory antibody to prothrombin that interacted with a calcium dependent epitope.

CONCLUSIONS

Successful treatment of the lymphoma resulted in clearance of the antibody and complete correction of all hemostatic abnormalities and manifestations. An acquired prothrombin deficiency has not been reported previously in association with a malignancy, and this patient represents the first such documented case.

Acquired factor VIII inhibitor in a patient with chronic myelogenous leukemia receiving interferon-alfa therapy

OBJECTIVE

To report a case of an acquired factor VIII inhibitor associated with the use of interferon-alfa.

CASE SUMMARY

A 58-year-old white man with newly diagnosed chronic myelogenous leukemia (CML) was initially treated with hydroxyurea. Interferon-alfa therapy was started six weeks later in order to enhance the response, with gradual reduction and eventual discontinuation of hydroxyurea. Interferon-alfa was continued for one year. Following bone marrow aspiration at one year, the patient developed significant bleeding and bruising at the site of extraction. His hemoglobin decreased from 11.3 to 9.3 g/dL and his activated partial thromboplastin time was elevated at 72 seconds. The factor VIII concentration was 0.02 units/mL; factor VIII inhibitor concentration was 58 Bethesda units. A diagnosis of an acquired factor VIII inhibitor was made, and the patient was treated with activated factor VII concentrates and prednisone. Interferon-alfa was discontinued, and the inhibitor subsequently disappeared over the next six weeks. The patient did not have any further bleeding problems.

DISCUSSION

Acquired factor VIII inhibitors other than in patients with hemophilia are rare. To date, there are no reported cases of factor VIII inhibitors associated with CML. Moreover, the temporal association with interferon-alfa administration suggests a causal relationship. There are only two previous case reports suggesting interferon-alfa as a cause of factor VIII inhibitors.

CONCLUSIONS

Induction of factor VIII inhibitors is a serious potential complication of therapy with interferon-alfa. We suggest that a diagnosis of an acquired factor VIII inhibitor be considered in patients who experience unexplained bleeding with interferon-alfa therapy.

Acquired hemophilia in patients with hematologic malignancies

OBJECTIVES

To evaluate the occurrence of acquired hemophilia in patients with hematologic malignancies and to assess their response to treatment.

DESIGN

Data on 8 patients with hematologic neoplastic disorders and inhibitor against factor VIII were analyzed retrospectively.

SETTING

Three large tertiary-care centers.

RESULTS

All 8 patients presented with spontaneous or posttraumatic hemorrhages. The mean inhibitor titer at the time of diagnosis was 79 Bethesda units (BU), and residual factor VIII activity was detectable in 3 patients. The inhibitor disappeared in 5 patients after a mean of 92 days, but persisted in the 3 other patients. The patients who achieved complete resolution of their circulating anticoagulant had lower mean inhibitor titers at the time of diagnosis than those who had persistent inhibitor (27 BU vs. 167 BU, respectively). Two patients died as a result of major hemorrhages that did not respond to treatment.

CONCLUSIONS

Antibodies against factor VIII may be responsible for some bleeding episodes in patients with lymphoid or myeloid malignancies. Acquired hemophilia in this setting should be differentiated from other causes of bleeding because the approach to treatment is different. No conclusion can be drawn regarding the association between the activity of the underlying illness and the inhibitor titer, although it appears that at least in some patients such a relationship may exist. The underlying pathogenetic mechanisms responsible for the production of autoantibodies against factor VIII remain unclear, but we provide a few explanations in this article.