Measurement of rivaroxaban concentrations demonstrates lack of clinical utility of a PT, dPT and APTT test in estimating levels

INTRODUCTION

Rivaroxaban concentrations were measured in 127 inpatient samples using an HPLC-MS/MS assay.

METHODS

We compared this measurement with a calibrated anti-Xa assay and performed PT, aPTT and dilute PT tests to assess the value of clot-based assays in clinical decision-making.

RESULTS

The correlation between the anti-Xa assay and the HPLC-MS/MS at therapeutic concentrations was strong (R²  = 0.98). The PT, RecombiPlasTin 2G, and aPTT, Actin FS, showed a linear dose-response but poor correlation (R²  = 0.32 and 0.44, respectively) and at dilutions of 1 in 150 to 1 in 750 the dilute PT assay also showed poor correlation with rivaroxaban concentrations measured by specific assays. A normal PT or aPTT alone did not identify a likely safe rivaroxaban concentration to allow surgery or invasive procedures, but the combination of normal PT and aPTT identified a group of patients with rivaroxaban levels less than 90 ng/mL. Combined normal PT and aPTT had specificity and sensitivity of 0.97 (95% CI 0.92-0.99) and 0.37 (95% CI 0.1-0.74) for a rivaroxaban concentration < 32 ng/mL.

CONCLUSIONS

The PT and aPTT show poor correlation with rivaroxaban levels measured by calibrated anti-Xa and HPLC-MS/MS assays. A normal combined PT and APTT identified low rivaroxaban levels with high specificity but lacked sensitivity. The dPT assay at several dilutions could not be used to quantify rivaroxaban in clinical samples. The utility of these PT, aPTT and dilute PT assays in a clinical setting is very limited, and results generated must be interpreted with caution.

Presenting ADAMTS13 antibody and antigen levels predict prognosis in immune-mediated thrombotic thrombocytopenic purpura

Immune-mediated thrombotic thrombocytopenic purpura (TTP) is a life-threatening disorder caused by antibodies against ADAMTS13. From the United Kingdom TTP registry, we undertook a prospective study investigating the impact of the presenting anti-ADAMTS13 IgG antibody and ADAMTS13 antigen on mortality. A total of 312 episodes involving 292 patients over 87 months were included; 68% were female, median age 46 (range, 11-88 years), and median presenting ADAMTS13 of <5% (range, <5%-18%). The mortality rate was 10.3% (n = 32); 68% of patients had a raised troponin at presentation conferring a sixfold increase in mortality compared with those with normal troponin levels (12.1% vs 2.0%, P = .04). Twenty-four percent had a reduced Glasgow Coma Score (GCS) at presentation with a ninefold increase in mortality (20% vs 2.2% for normal GCS at presentation, P < .0001). Mortality increased with higher anti-ADAMTS13 antibody levels and lower ADAMTS13 antigen levels. Those with antibody levels in the upper quartile (antibody >77%) had a mortality of 16.9% compared with 5.0% for the lowest quartile (antibody <20%) (P = .004). Those with an antigen level in the lowest quartile (antigen <1.5%) had a mortality of 18% compared with 3.8% for the highest quartile (antigen >11%) (P = .005). The synergistic effect of anti-ADAMTS13 IgG antibody in the upper quartile and ADAMTS13 antigen in the lowest quartile had the highest mortality of 27.3%. We conclude that both anti-ADAMTS13 IgG antibody and ADAMTS13 antigen levels correlate with outcome in TTP with increased cardiac and neurological involvement and increased mortality.

An observational study of direct oral anticoagulant awareness indicating inadequate recognition with potential for patient harm

Essentials Ignorance of direct oral anticoagulants' effects on coagulation tests may be a safety issue. An electronic questionnaire was sent to prescribers in NHS Grampian with 143 respondents. We found widespread evidence of inappropriate interpretation of the clinical scenarios given. The study suggests potential for patient harm due to lack of knowledge and education is required.

SUMMARY

Background Lack of awareness of the nature of the direct oral anticoagulants (DOACs) combined with the poor correlation between routine coagulation test prolongation and the activity of these drugs represents a potential for patient harm. Objectives To establish the level of awareness of the different DOACs, and to assess whether prescribers were able to recognize the state of anticoagulation in a hypothetical patient. Methods and results An electronic questionnaire was sent by email to prescribers in our health board. Among 143 respondents, we found significant differences in awareness of the currently licensed drugs. Of the respondents, 88%, 80% and 50%, respectively, recognized rivaroxaban, dabigatran, and apixaban. When provided with a routine clinical situation, only 13.5%, 17.5% and 16.8%, respectively, recognized that the hypothetical patient was anticoagulated, and only 55-58% recognized that it was unsafe to proceed with an invasive procedure. Conclusion These results indicate a significant risk for patient harm related to lack of knowledge about this new group of frequently used drugs, and indicate that additional education and training on this subject are required.

Oral direct inhibitors of coagulation

For the first time in 50 years new oral anticoagulants of proven efficacy and with acceptable safety profiles are available for patients with atrial fibrillation and venous thromboembolism. Here is a brief overview of the benefits and possible disadvantages of using these drugs.

Assessment of von Willebrand disease as a risk factor for primary postpartum haemorrhage

It is not clear whether von Willebrand disease (VWD) is associated with an increased risk of postpartum haemorrhage (PPH). We assessed the effect of VWD on PPH in a case-control study. Logistic regression was used to test for differences in the odds of PPH in deliveries to women with and without VWD, before and after adjustment for known risk factors. A total of 62 deliveries in 33 women with VWD were compared with controls matched for age, year of delivery and parity. Primary PPH was observed in 12/62 (19.4%) deliveries in women with VWD and 16/124 (12.9%) controls. The unadjusted odds ratio (OR) for VWD as a risk factor for PPH was 1.62 (95% CI 0.75-3.49, P = 0.22). After adjustment for other risk factors for PPH, the OR for VWD as a risk factor for PPH was 1.31 (95% CI 0.48-3.60, P = 0.60). PPH was observed in 7/24 (29%) deliveries in women known prepregnancy to have VWD. The unadjusted odds for VWD as a risk factor for PPH in this group was significantly greater than the control group (OR 2.78 (95% CI 1.03-7.49) P = 0.043) and remained significant after adjusting for other significant risk factors (OR 3.41 (95% CI 1.07-10.9) P = 0.038). VWD in itself may not be a significant risk factor for PPH, however, women known to have VWD predelivery may represent an at risk sub-group.

UKHCDO guidelines on the management of HCV in patients with hereditary bleeding disorders 2011

Chronic HCV infection continues to be of significant clinical importance in patients with hereditary bleeding disorders. This guideline provides information on the recent advances in the investigation and treatment of HCV infection and gives GRADE system based recommendations on the management of the infection in this patient group.

RVO--real value obscure

See also Carrier M, Rodger MA, Wells PS, Righini M, Le Gal G. Residual vein obstruction to predict the risk of recurrent venous thromboembolism in patients with deep vein thrombosis: a systematic review and meta-analysis. This issue, pp 1119-25; Le Gal G, Carrier M, Kovacs MJ, Betancourt MT, Kahn SR, Wells PS, Anderson DA, Chagnon I, Solymoss S, Crowther M, Righini M, Delluc A, White RH, Vickars L, Rodger M. Residual vein obstruction as a predictor for recurrent thromboembolic events after a first unprovoked episode: data from the REVERSE cohort study. This issue, pp 1126-32.

Model thrombi formed under flow reveal the role of factor XIII-mediated cross-linking in resistance to fibrinolysis

BACKGROUND

Activated factor XIII (FXIIIa), a transglutaminase, introduces fibrin-fibrin and fibrin-inhibitor cross-links, resulting in more mechanically stable clots. The impact of cross-linking on resistance to fibrinolysis has proved challenging to evaluate quantitatively.

METHODS

We used a whole blood model thrombus system to characterize the role of cross-linking in resistance to fibrinolytic degradation. Model thrombi, which mimic arterial thrombi formed in vivo, were prepared with incorporated fluorescently labeled fibrinogen, in order to allow quantification of fibrinolysis as released fluorescence units per minute.

RESULTS

A site-specific inhibitor of transglutaminases, added to blood from normal donors, yielded model thrombi that lysed more easily, either spontaneously or by plasminogen activators. This was observed both in the cell/platelet-rich head and fibrin-rich tail. Model thrombi from an FXIII-deficient patient lysed more quickly than normal thrombi; replacement therapy with FXIII concentrate normalized lysis. In vitro addition of purified FXIII to the patient's preprophylaxis blood, but not to normal control blood, resulted in more stable thrombi, indicating no further efficacy of supraphysiologic FXIII. However, addition of tissue transglutaminase, which is synthesized by endothelial cells, generated thrombi that were more resistant to fibrinolysis; this may stabilize mural thrombi in vivo.

CONCLUSIONS

Model thrombi formed under flow, even those prepared as plasma 'thrombi', reveal the effect of FXIII on fibrinolysis. Although very low levels of FXIII are known to produce mechanical clot stability, and to achieve γ-dimerization, they appear to be suboptimal in conferring full resistance to fibrinolysis.

Platelet and coagulation activation markers in myeloproliferative diseases: relationships with JAK2 V6I7 F status, clonality, and antiphospholipid antibodies

BACKGROUND AND OBJECTIVES

Patients with myeloproliferative disease (MPD) have an increased risk of thrombosis. We studied markers of platelet and coagulation activation in a large cohort of patients with MPD (n = 118) and related this to Janus Kinase 2 (JAK2) V617 F mutation status, a marker of clonality, and the presence of antiphospholipid antibodies (APA), all of which have been associated with thrombosis in MPD.

METHODS

D-dimer, thrombin-antithrombin complexes (TAT), prothrombin fragments 1 + 2 (F(1+2)), soluble E-selectin (sE-selectin), and soluble P-selectin (sP-selectin) levels were compared between patients and hypertensive controls (n = 127). Assays for lupus anticoagulant (LA), anticardiolipin antibodies (ACA), antibeta2 glycoprotein 1 antibodies (anti-beta(2)GP1), and antiprothrombin antibodies (alpha-Pro) were also performed. The JAK2 V617F mutation status was determined in the cohort using amplification refractory mutation system (ARMS) polymerase chain reaction. Disease clonality was determined in 54 patients using the HUMARA assay.

RESULTS

sP-selectin was significantly increased in patients with MPD (P

CONCLUSIONS

The JAK2 V617F mutation is associated with platelet activation, as measured by elevated sP-selectin levels, in MPD. In contrast to previous reports, we found no excess of APA in patients with MPD.

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Key Words Collapse

MESH Headings

• Adult
• Aged
• Aged, 80 and over
• Antibodies, Antiphospholipid/chemistry
• Blood Coagulation
• Blood Platelets/cytology
• Blood Platelets/metabolism
• Cohort Studies
• Female
• Humans
• Janus Kinase 2/genetics
• Male
• Middle Aged
• Myeloproliferative Disorders/genetics
• Myeloproliferative Disorders/metabolism
• Thrombosis/genetics

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Grants Collapse

Approach to the diagnosis and management of mild bleeding disorders

Symptoms suggestive of the presence of a mild bleeding tendency are commonplace. Whilst the majority with such symptoms are healthy, it is important to identify those with bleeding disorders in order to manage symptoms, to minimize risk from invasive procedures and to avoid unnecessary exposure to blood products. Thorough clinical assessment remains the cornerstone of the diagnostic strategy for mild bleeding disorders, although the sensitivity and specificity of the clinical history and examination are limited. When clinical suspicion is aroused the use of a staged protocol of laboratory investigations is appropriate, but the limitations of currently available tests of primary hemostasis and blood coagulation must be recognized if diagnostic errors are to be avoided. Whilst there is considerable current interest in global assays of hemostasis and coagulation, none has yet been demonstrated conclusively to be more effective than the more standard approach. Iatrogenic bleeding has increasing prominence in clinical practise. The expanding use of anticoagulants and platelet inhibitor drugs has resulted in an increased proportion of the population being at risk of abnormal bleeding. Knowledge of the levels of risk associated with particular drugs and combinations, and the advantages and hazards of interruption of drug use for planned interventional procedures, are essential in order to reduce the incidence of iatrogenic bleeding. Prevention and treatment of hemorrhage in subjects with mild bleeding disorders includes the application of general measures, including attention to surgical technique, measures specific to the precise diagnosis, and less specific treatments that enhance hemostasis and coagulation or inhibit fibrinolysis. The last of these includes the widely prescribed drugs desmopressin, aprotinin, epsilon aminocaproic acid and tranexamic acid. Data are now available on their efficacy and safety in a range of clinical situations.

Ethnicity-specific gene-gene interaction between IL-13 and IL-4Ralpha among African Americans with asthma

RATIONALE

Genes in the interleukin (IL)-4/IL-13/IL-4Ralpha pathway have been shown to be associated with asthma and related phenotypes in some populations, but not in others. Furthermore, interaction between these genes has been shown to affect asthma in white and Chinese populations.

OBJECTIVES

To determine whether there are IL-4/IL-13 and IL-4Ralpha gene-gene interactions that are associated with asthma in African Americans.

METHODS

Eighteen single-nucleotide polymorphisms (SNPs) in IL-4, IL-13, and IL-4Ralpha genes were genotyped in 264 African Americans with asthma and 176 healthy control subjects. We tested the SNPs for genetic associations and gene-gene interactions with asthma, baseline lung function, bronchodilator drug response, and total serum IgE levels.

MEASUREMENTS AND MAIN RESULTS

We identified 94 SNPs in IL-4, IL-13, and IL-4Ralpha genes by directly sequencing these genes in 24 African-American subjects with asthma. Seventeen SNPs were analyzed for association with asthma and related phenotypes. We found no evidence of association in the IL-4 gene. One SNP in the IL-13 gene (A-646G, rs2069743) and two SNPs in the IL-4Ralpha gene (A+4679G, rs1805010, and C+22656T, rs1805015) showed association with lung function (both baseline and post-bronchodilator). Although the association between individual SNPs and asthma-related phenotypes differed from previous studies performed in white and Chinese populations, significant gene-gene interaction was found between the IL-13 (A-646G) and IL-4Ralpha (A+4679G) SNPs for baseline lung function among African-American subjects with asthma.

CONCLUSIONS

Gene-gene interaction between the IL-13 and IL-4Ralpha genes may play an important role in asthma among African Americans.

The PTGDR gene is not associated with asthma in 3 ethnically diverse populations

BACKGROUND

The prostanoid DP receptor (PTGDR) gene on chromosome 14q22.1 has been identified as an asthma susceptibility gene. A haplotype with decreased transcription factor binding and transcription efficiency was associated with decreased asthma susceptibility in African American and white subjects. The significance of PTGDR gene variants in asthma has yet to be determined in Latinos, the largest US minority population, nor has the association been replicated in other populations.

OBJECTIVE

To determine the role of PTGDR gene variants in asthma susceptibility and asthma-related traits among the Mexican, Puerto Rican, and African American populations.

METHODS

We determined whether single nucleotide polymorphisms (SNPs) and haplotypes in PTGDR were associated with asthma and asthma-related traits by family-based and cross-sectional cohort analyses in 336 Puerto Rican and 273 Mexican asthmatic trios and by case-control analysis among African American subjects with asthma and healthy controls (n = 352).

RESULTS

We identified 13 SNPs in the PTGDR gene, and 6 were further analyzed. There was no significant association between PTGDR variants and asthma by family-based or case-control analyses. SNPs -441C and -197C and haplotype TTT showed marginal association with asthma-related traits in Mexican subjects. SNP -441 genotype TT (P = .05) and haplotype TTT (P = .02) were associated with increased IgE levels in African Americans.

CONCLUSION

We conclude that the PTGDR gene is not a significant risk factor for asthma among Puerto Ricans, Mexicans, or African Americans.

CLINICAL IMPLICATIONS

Asthma candidate genes provide insights to pathophysiology and potentially new therapeutic targets, although the PTGDR gene was not found to be a significant risk factor for asthma in 3 populations.

Beta 2-adrenergic receptor polymorphisms: pharmacogenetic response to bronchodilator among African American asthmatics

Beta2-adrenergic receptor (beta2AR) gene polymorphisms have been reported to be associated with various asthma-related traits in different racial/ethnic populations. However, it is unknown whether beta2AR genetic variants are associated with asthma in African Americans. In this study, we have examined whether there is association between beta2AR genetic variants and asthma in African Americans. We have recruited 264 African American asthmatic subjects and 176 matched healthy controls participating in the Study of African Americans, Asthma, Genes and Environments (SAGE). We genotyped seven known and recently identified beta2AR SNP variants, then tested genotype and haplotype association of asthma-related traits with the beta2AR SNPs in our African American cohort with adjustment of confounding effect due to admixture background and environmental risk factors. We found a significant association of the SNP -47 (Arg-19Cys) polymorphism with DeltaFEF(25-75), a measure of bronchodilator drug responsiveness, in African American asthmatics after correction for multiple testing (P = 0.001). We did not observe association of the SNP +46 (Arg16Gly) variant with asthma disease diagnosis and asthma-related phenotypes. In contrast to previous results between the Arg16Gly variant and traits related to bronchodilator responsiveness, our results indicate that the Arg-19Cys polymorphism in beta upstream peptide may play an important role in bronchodilator drug responsiveness in African American subjects. Our findings highlight the importance of investigating genetic risk factors for asthma in different populations.

A comparison of computerised strain gauge plethysmography with D-dimer testing in screening for deep-vein thrombosis

There has been a significant increase in the amount of diagnostic testing performed to confirm or refute a diagnosis of deep-vein thrombosis (DVT), often in low-risk patients. D-dimer testing and computer-assisted strain gauge plethysmography (SGP) are rapid, inexpensive methods of excluding DVT and, in combination with a clinical probability score for DVT, both have been used to accurately exclude DVT. D-dimer testing, SGP and a combination of both in excluding DVT were compared in 243 ambulant outpatients who followed a prespecified investigation protocol. The negative-predictive value of D-dimer testing alone was 100%, 93.9% (95% CI 93.6-94.1) and 80% (95% CI 73.7-86.3) in patients with a low, moderate and high pretest probability (PTP) score for DVT respectively. The corresponding results for SGP were 95.6% (95% CI 95.5-95.7), 86.1% (95% CI 85.9-86.4) and 77.8% (95% CI 75.9-79.7) in patients with a low, moderate and high PTP score for DVT respectively. D-dimer testing provided a rapid, cost-effective method for excluding DVT in low-risk ambulant patients, which was superior to SGP. Combined use of the modalities did not improve any aspect of clinical decision making.

Admixture-matched case-control study: a practical approach for genetic association studies in admixed populations

Case-control genetic association studies in admixed populations are known to be susceptible to genetic confounding due to population stratification. The transmission/disequilibrium test (TDT) approach can avoid this problem. However, the TDT is expensive and impractical for late-onset diseases. Case-control study designs, in which, cases and controls are matched by admixture, can be an appealing and a suitable alternative for genetic association studies in admixed populations. In this study, we applied this matching strategy when recruiting our African American participants in the Study of African American, Asthma, Genes and Environments. Group admixture in this cohort consists of 83% African ancestry and 17% European ancestry, which was consistent with reports from other studies. By carrying out several complementary analyses, our results show that there is a substructure in the cohort, but that the admixture distributions are almost identical in cases and controls, and also in cases only. We performed association tests for asthma-related traits with ancestry, and only found that FEV(1), a measure for baseline pulmonary function, was associated with ancestry after adjusting for socio-economic and environmental risk factors (P=0.01). We did not observe an excess of type I error rate in our association tests for ancestry informative markers and asthma-related phenotypes when ancestry was not adjusted in the analyses. Furthermore, using the association tests between genetic variants in a known asthma candidate gene, beta(2) adrenergic receptor (beta(2)AR) and DeltaFEF(25-75), an asthma-related phenotype, as an example, we demonstrated population stratification was not a confounder in our genetic association. Our present work demonstrates that admixture-matched case-control strategies can efficiently control population stratification confounding in admixed populations.

Air travel and thrombosis

The current literature suggests a weak association between long-distance travel and the development of asymptomatic venous thromboembolism (VTE). Most of the data available relate to air travel and suggest that the risk is largely confined to asymptomatic calf vein thrombosis in passengers with additional risk factors for VTE, travelling for more than 8 h. The risk of both symptomatic and fatal pulmonary embolism (PE) is very small. The causal role of travel-related factors (e.g. stasis, dehydration, cramped seats and hypobaric hypoxia) is not yet proved but, given the plausible risk-free benefit, all passengers should be advised to maintain adequate hydration and exercise. There is currently no evidence for 'routine' thromboprophylaxis using stockings or drugs. In passengers with additional risk factors for VTE, thromboprophylaxis in the form of below-knee graduated compression stockings (providing 15-30 mmHg at the ankle) and/or prophylactic dose low-molecular-weight heparin may be considered. The evidence does not support the use of aspirin, which is associated with a significant rate of adverse gastrointestinal effects.

Impact of introducing guidelines on anticoagulant reversal

The production of clinical guidelines has become an accepted and lauded part of modern medicine. It is also widely perceived that these guidelines provide some sort of panacea for the problems that medicine faces. Our experience suggests otherwise. Triggered by on going anecdotal evidence of poor practice, we reviewed the effect on practice of a recently introduced local guideline on the management of major bleeding in patients on warfarin. Comparing 34 patients treated before and 48 patients after the introduction of the guideline, we found no significant improvement in prothrombin complex concentrate dosing or administration of vitamin K. The only improvement witnessed was in early assessment of the effect of the intervention on coagulation which improved from 10 to 35% of cases. Of major concern, in 10% of cases, there was no documentation to confirm or refute that prothrombin complex concentrate (PCC), which had been issued, had actually been administered to the patient. The production and widespread dissemination of this local guideline did not achieve significant improvement in clinical practice. Possible reasons for failure to adhere to the guideline are discussed.

Drug-induced methaemoglobinaemia presenting with angina following the use of dapsone

Anaemia may result in tissue hypoxia which may induce or exacerbate symptoms of ischaemia. Tissue hypoxia may however also result from the presence of haemoglobin with altered oxygen-binding characteristics. Drug-induced methaemoglobinaemia in which oxygen is irreversibly bound to haemoglobin may complicate the use of some common drugs. This condition may result in severe tissue hypoxia, which is rapidly and cheaply reversed by methylene blue.

Immunization of patients with bleeding disorders

The immunization of patients with bleeding disorders differs from that of the normal population with respect to the risk of haematoma formation at the vaccination site and the unusual infective risks associated with the potential, and past, exposure to blood products. Most vaccinations can be given subcutaneously and this should be the preferred route. All routine childhood vaccinations should be given at the appropriate time. All patients with bleeding disorders should be vaccinated against hepatitis A and B. HIV positive patients should receive annual influenza vaccinations and should avoid the oral polio, oral typhoid, BCG and yellow fever vaccines.

Laboratory testing for prothrombotic states: clinical utility

It is possible to detect a genetic contribution to venous thrombosis in a significant proportion of patients. This has led to a huge expenditure in clinical time and health resource. However, the gains to be made from the uncritical investigation of the causes of venous thromboembolism are limited and the approach raises significant issues in relation to the appropriateness of this form of genetic testing. In contrast, there are some acquired prothrombotic states that should be identified because the risk of further thrombosis may be sufficient to influence therapy. These states include antiphospholipid syndrome, myeloproliferative disorders, and cancer.

Transfusion-associated graft-versus-host disease in a patient with Waldenstrom's macroglobulinaemia

BACKGROUND AND OBJECTIVES

Routine irradiation of cellular blood products is not presently recommended for patients with non-Hodgkin's lymphoma (NHL).

MATERIALS AND METHODS

We report the case of a 72-year-old-man with Waldenstrom's macroglobulinaemia who developed transfusion-associated graft-versus-host disease (TA-GvHD) 13 days following a non-irradiated red cell transfusion.

RESULTS

The patient had not previously received purine analogues and none of the donors was homozygous for a human leucocyte antigen (HLA) haplotype that was shared by the recipient. Therefore, his only apparent risk factor was lymphoplasmacytoid NHL.

CONCLUSIONS

This case further strengthens the argument that NHL per se is a risk factor for TA-GvHD and supports the proposal that the guidelines for prophylactic irradiation of cellular blood products be extended to include all cases of NHL.

Rare acquired bleeding disorders

Accurate diagnosis of the cause of bleeding is a prerequisite for determination of the optimal therapeutic response. Clinicians are generally aware of the more prevalent hemorrhagic syndromes but some rare acquired conditions are also of importance. In many of these, inhibitors of coagulation factors or of platelet adhesion/aggregation cause bleeding. These inhibitors are generally, but not always, immunoglobulins. In this review, the less common inhibitors of coagulation and hemostasis, as well as some important but rare nutritional, iatrogenic and disease associated hemorrhagic disorders, are described.

A comparison of the efficacy and rate of response to oral and intravenous Vitamin K in reversal of over-anticoagulation with warfarin

The role of oral Vitamin K administration in the reversal of anticoagulation is not yet clear because of a paucity of data on the early effects of treatment, apparent differences in efficacy between preparations and a lack of data comparing oral with intravenous administration. We have compared the effects on the International Normalized Ratio (INR) and activities of the Vitamin K-dependent clotting factors II, VII, IX and X at 4 h and 24 h after administration of three oral Vitamin K preparations and of intravenous Vitamin K in 64 anticoagulated patients who required non-urgent partial correction of anticoagulation. Our data confirm that correction of anticoagulation is more rapid after intravenous administration of Vitamin K than after oral administration of similar or larger doses. At 24 h, satisfactory correction of INR can be achieved using low-dose Vitamin K given by either the intravenous or oral route. Our data, and that from previous studies, suggest that there may be differences in efficacy between orally administered products. Administration of Vitamin K by either route was accompanied by changes in the activities of the Vitamin K-dependent clotting factors that reflected their respective biological half-lives. In the 24 h after treatment, the relationship between the INR and the individual Vitamin K-dependent clotting factors was similar to that described previously in stable anticoagulated patients. We conclude that the reversal of anticoagulation with warfarin is achieved more rapidly by intravenous administration of Vitamin K. Satisfactory, but slower, reversal of anticoagulation can be effected using oral Vitamin K, but there may be differences in efficacy between the products tested in our study.

Acquired haemophilia in association with organ-specific autoimmune disease

A 72-year-old woman presented with multiple sites of soft tissue bleeding and a left ulnar neuropathy due to a compartment syndrome. There were also clinical signs of hypothyroidism. Factor VIII:C (FVIII) levels were 6% and a FVIII inhibitor with a titre of 9 Bethesda units was detected. She had biochemical evidence of hypothyroidism and high titres of antithyroid antibodies were detected. Two episodes of life- or limb-threatening haemorrhage were successfully treated with FEIBA. The inhibitor disappeared following 2 months of immunosuppression with oral cyclophosphamide and corticosteroids. She then developed autoimmune haemolytic anaemia, which responded to further immunosuppression with oral prednisolone. The association between acquired haemophilia and systemic autoimmune disorders such as systemic lupus erythematosis is well recognized, but our description of an association with organ-specific autoimmunity is more unusual.

Inferior vena cava malformation as a risk factor for deep venous thrombosis in the young

Conditions which result in hypercoagulable blood or venous stasis may predispose to the development of deep vein thrombosis (DVT). Most of the recently described risk factors for DVT induce a hypercoagulable state. Over a 3-year period we have observed anomaly of the inferior vena cava (IVC) in four young patients presenting with spontaneous unprovoked DVT. This is a greater than expected rate (5% observed versus 0.5% expected). Further, bilateral DVT, which constitutes less than 10% of cases in most series, was present in three of the four cases. Anomaly of the IVC is a rare example of a prevalent congenital condition that predisposes to DVT, presumably by favouring venous stasis. This diagnosis should be considered in young patients with spontaneous and bilateral DVT.

Incidence and associations of acute renal failure complicating high-dose intravenous immunoglobulin therapy

In a formal study, we have identified increasing age, pretreatment renal impairment and diabetes mellitus as risk factors for the development of intravenous immunoglobulin-induced renal failure. Identification of these characteristics in potential recipients should alert clinicians to the associated increased risk of this serious complication.

Combined risk factors contributing to cerebral venous thrombosis in a young woman

Cerebral venous thrombosis is a rare condition affecting predominantly adolescents or young adults. The presentation is often non-specific, and delay in diagnosis is common. The otolaryngologist may be consulted about the radiological findings of lateral sinus thrombosis and mastoid changes. The association of congenital thrombophilia with unusual presentations of venous thrombosis, especially in young individuals is now well documented. We present a case of lateral and sagittal sinus thrombosis complicated by cerebral venous infarction in a girl with protein C deficiency and masked mastoiditis. Unusual forms of venous thrombosis, including cerebral venous thrombosis may develop in association with a single risk factor for thrombosis, but additional risk factors should be sought especially when thrombosis presents in very young individuals. This case draws attention to the multi-causal nature of cerebral venous thrombosis in young adults, and highlights the issue of masked mastoiditis. A coordinated approach by otolaryngological and haematological teams is recommended in such cases.

Sight-threatening varicella zoster virus infection after fludarabine treatment

Varicella zoster virus (VZV) infection involving the posterior segment of the eye after fludarabine treatment has not previously been described. Two patients, who had completed fludarabine treatment 3 and 18 months previously, presented with visual loss that had been preceded by a recent history of cutaneous zoster. The use of the polymerase chain reaction (PCR) for VZV DNA from ocular specimens allowed rapid confirmation of clinical diagnosis and treatment with a good outcome in one patient. With the increasing use of fludarabine and other purine analogues, an awareness of such complications is important because of their potentially sight-threatening consequences.

Transfusion associated graft versus host disease in an immunocompetent individual following coronary artery bypass grafting

Transfusion associated graft versus host disease (TA-GVHD) is a rare but commonly fatal complication of transfusion of cellular blood products, which usually occurs in immunosuppressed individuals following transfusion and subsequent engraftment of viable T lymphocytes. Very rarely it may arise in apparently immuno-competent individuals. A case is reported of TA-GVHD in a non-immunocompromised 60 year old white man, resulting from red cell transfusion after coronary artery bypass grafting. HLA typing confirmed homozygosity of the donor for an HLA type shared by the recipient--the classic scenario for the development of TA-GVHD in immunocompetent individuals. The patient died 21 days after transfusion. There is a perceived increased risk of TA-GVHD following bypass grafting and other surgical procedures where cardiopulmonary bypass is required. TA-GVHD is probably underreported and the incidence in the UK is felt to be too low to warrant routine irradiation of cellular products for this group of patients. Clinicians, pathologists, and transfusion centres should be aware of this rare but devastating complication of blood transfusion after cardiac surgery.

Evolution of zidovudine resistance-associated genotypes in human immunodeficiency virus type 1-infected patients

Substantial differences have been described in the response of individual patients to zidovudine (ZDV) therapy, both in the clinical impact and in virus load. Genotypic changes associated with the appearance of drug resistance may also be different or occur at different rates. We have obtained the nucleotide sequence of the RT domain of individual HIV-1 genomes extracted from 10 plasma and peripheral blood mononuclear cell (PBMC) samples donated by two haemophiliac patients before, during, and after long-term ZDV therapy. Although the plasma virus load was similar throughout, the order and timing of appearance of resistance-associated substitutions differed in the two patients. In patient p74, K70R appeared after 4 months, T215Y at 5.5 months, and M41L at 13 months. In p87, K70R also appeared at 4 months, but T215Y and K219Q were not observed until 18 months and M41L not at all. Much greater sequence change overall occurred in p74. The evolution of the viral population in that patient was dominated by the unique appearance of T215Y and subsequently M41L, with all sequences from the last time point being descended by a single path from the pretreatment samples. However, in p87, several different lineages of RT sequences were found to persist throughout treatment. We propose that these differences in outcome may be determined by differences in genetic background at sites other than the five generally considered to be associated with ZDV sensitivity.

Absence of hepatitis A virus transmission by high-purity solvent detergent treated coagulation factor concentrates in Scottish haemophiliacs

Recent reports of hepatitis A virus (HAV) infection in haemophiliacs receiving high-purity solvent detergent (HP.SD) treated factor VIII concentrates have brought into question the efficacy of this virucidal method for inactivating HAV. To assess whether HAV may have been transmitted by HP.SD concentrates, we compared seroprevalence in haemophiliacs with different disease severity, sought evidence of seroconversion to HAV since introduction of HP.SD products, and directly examined concentrates for HAV RNA by PCR. Our data suggest that Scottish haemophiliacs are not being infected with HAV by HP.SD concentrates produced initially by CRTS Lille and presently by PFC Edinburgh and supplied by the Scottish National Blood Transfusion Service (SNBTS).

Frequent reinfection and reactivation of hepatitis C virus genotypes in multitransfused hemophiliacs

The frequency and dynamics of infection with different genotypes of hepatitis C virus were investigated in a cohort of hemophiliacs repeatedly exposed to non-virus-inactivated clotting factor. Among 63 infected hemophiliacs, genotype 1 (n = 38, subtypes 1a [27] and 1b [11]) was predominant; genotypes 2a (n = 1), 2b (n = 3), 3a (n = 20), and 5a (n = 1) accounted for the remainder. This distribution was similar to that found in Scottish blood donors from whom the infected blood products were manufactured. Hemophiliacs with severe disease were more likely to be polymerase chain reaction-positive than those with moderate or mild disease. Over 10 years, changes in the circulating major genotype and serotype were observed in 9 of 29 hemophiliacs and from one subtype to another in 3, although there was no clear trend toward replacement with any particular variant. Replacement occurred after the introduction of inactivated clotting factor in 4 subjects, implicating reactivation rather than reinfection. Those coinfected with human immunodeficiency virus were more likely to show a change in genotype.

Virus-associated haemophagocytic syndrome: further evidence for a T-cell mediated disorder

A 16-year-old youth with life-threatening virus-associated haemophagocytic syndrome (VAHS) responded remarkably to treatment with cyclosporin A during two periods of active disease, the second of which was due to noncompliance with treatment. Our clinical observations support the hypothesis that VAHS is cytokine driven as a result of an aberrant T-cell response to infection.

Warfarin and epistaxis--a case controlled study

Patients anticoagulated with warfarin form a small proportion of those admitted with epistaxis annually to ENT units. The authors formed the impression that such patients spend longer in hospital and have more complicated management than controls. A prospective age and sex matched controlled study of 20 consecutive patients admitted with epistaxis whilst anticoagulated was performed. This showed that these patients spent significantly longer in hospital than controls, with an additional expense in the study period of 10,500 pounds for inpatient bed nights alone. The management of these patients is more complicated and there is a subgroup of poorly controlled patients who present most of the problems. A potential solution is to improve community warfarin control and to involve general practitioners and haematologists in the re-establishment of warfarin following admission for epistaxis.

An HIV positive haemophiliac with acute lymphoblastic leukaemia successfully treated with intensive chemotherapy and syngeneic bone marrow transplantation

A 26-year-old HIV positive severe haemophiliac developed Burkitt-type acute lymphoblastic leukaemia with intracranial involvement. He underwent standard combination therapy, and entered complete remission. Syngeneic bone marrow transplantation (BMT) was undertaken; the donor was also HIV positive. The patient died 18 months from transplant of isolated intracranial relapse, with no evidence of systemic relapse. Unlike other types of non-Hodgkin's lymphoma, Burkitt's type occurs in HIV positive patients with relatively normal CD4 cell counts. Remission can be achieved using intensive chemotherapy, and since these patients may otherwise have a reasonable life expectancy, BMT may be appropriate.

Use of several second generation serological assays to determine the true prevalence of hepatitis C virus infection in haemophiliacs treated with non-virus inactivated factor VIII and IX concentrates

To investigate the prevalence of hepatitis C virus infection in two risk groups, stored serum samples from treated haemophiliacs and intravenous drug users were tested for anti-HCV by both anti-C-100 based and second generation ELISAs (Abbott and Ortho) followed by testing in two confirmatory immunoblot assays that incorporate core as well as other non-structural antigens (Innogenetics LIA and Chiron RIBA-HCV test). Clear evidence of HCV infection was found in all but one of 78 haemophiliacs treated with non-virus inactivated clotting factor concentrates, but in none exposed only to super dry heat-treated concentrates. Only four samples gave rise to conflicting serological results between the four tests, two of these occurred in patients with advanced HIV related disease and almost certainly reflected loss of humoral immunity associated with disease progression, and the others occurred in the only two patients tested who were chronic carriers of hepatitis B infection and may reflect an interaction between the two viruses. Comparison of anti-C-100 versus second generation tests in immunocompetent drug users revealed a false negative rate of 20% using C-100 alone, indicating the advantage of using second generation assays for detection of past or current HCV infection. Of all of the antigens used in the confirmatory assay, positive sera showed strongest and most frequent reactivity with the C22 and C33c proteins (Ortho RIBA).

Immunological abnormalities in haemophiliacs

10 years ago, it became apparent that haemophiliacs were developing diseases which were indicative of underlying immunodeficiency. The results of investigation confirmed that many had abnormal immune systems, particularly with regard to cell-mediated immunity. These abnormalities were thought to be a consequence of the use of clotting factor concentrates, and indeed the discovery of HIV and its mode of transmission, confirmed these suspicions. However, it subsequently became clear that HIV infection did not explain all the abnormalities observed. Many in vivo studies have shown that the immune systems of HIV-negative haemophiliacs are not entirely normal, and in vitro studies have shown that clotting factor concentrates per se have a modulating effect on immune function. We have reviewed particularly the abnormalities seen in HIV-negative haemophiliacs and their possible causes, as well as the specific features of HIV infection in haemophiliacs.

Hepatitis C quantification and sequencing in blood products, haemophiliacs, and drug users

The polymerase chain reaction (PCR) detected specific hepatitis C viral (HCV) RNA sequences in plasma from 15 of 21 haemophiliacs (12 HCV-antibody positive) and 7 of 27 intravenous drug users (13 HCV-antibody positive). Quantification of RNA-positive samples showed high levels of HCV (10(5) to 10(6) copies of RNA/ml) in infected patients. HCV was more frequently found in haemophiliacs infected with human immunodeficiency virus (11/11 HIV-positive and 4/10 HIV-negative patients). HCV-RNA was detected in all batches of commercially available factor VIII tested and in low concentrations in some pools of plasma donations from volunteers. Factor VIII, manufactured from volunteer donations, was uniformly negative by PCR. Phylogenetic analysis of viral sequences showed two distinct groups: one was associated with intravenous drug users and the other with haemophiliacs infected with Scottish factor VIII preparations. Both were distinct from sequences found in commercially available factor VIII.