Analytical Performance Evaluation of Automated Coagulation Analyzer CP3000 for Routine and Special Coagulation Assays.

CP3000 coagulation analyzer is a high-throughput, fully automated coagulation analyzer. The objective of this study was to evaluate the analytical performance of CP3000 coagulation system for general and special coagulation analyses. Quality control materials and patient samples were used to evaluate the analytical performance of CP3000 coagulation system. Precision, carryover, linearity, comparability with ACL-TOP 700 coagulation system, and verification of reference range were evaluated or performed according to Clinical and Laboratory Standards Institute guidelines. Within-run and between-run precisions were below 5% for both normal and abnormal ranges. There was no detectable carryover. The linearity of antithrombin and fibrinogen were excellent. The comparability between CP3000 and ACL-TOP 700 coagulation systems was acceptable except for activated partial thromboplastin time and thrombin time due to differences in reagent composition. Reference ranges proposed by the manufacturer were verified to be acceptable. CP3000 coagulation system is a reliable system that can be used to perform routine and special coagulation tests rapidly and accurately. Because of its small footprint as an additional advantage, the implementation of CP3000 coagulation system can be efficient in hospital laboratories of various sizes.

Routine coagulation testing in Vacutainer® Citrate Plus tubes filled at minimum or optimal volume.

Background Filling of citrate tubes with appropriate amount of blood is essential for obtaining reliable results of coagulation testing. This study aimed to verify whether results of routine coagulation tests are comparable when the new Becton Dickinson Vacutainer® Citrate Plus tubes are filled at minimum or optimal volume. Methods The study population consisted of 133 patients (40 on oral anticoagulant therapy), who had blood collected for routine coagulation testing. Two sequential Vacutainer® Citrate Plus tubes of the same type and lot were drawn. The first tube was collected after a butterfly needle was inserted into the vein, so that the air in the tubing was aspirated into the tube before blood (minimum fill volume), whilst the second was drawn at optimal fill volume. Experiments were repeated using 2.7-mL (n = 86) and 1.8-mL (n = 47) tubes. Results Prothrombin time (PT) and fibrinogen values were slightly but significantly decreased in tubes with minimum than in those with optimal fill volume. The activated partial thromboplastin time (APTT) was slightly prolonged in tubes with minimum than in those with optimal fill volume, but the difference was not statistically significant. An identical trend was noted in separate analyses for the 2.7-mL and 1.8-mL tubes. Spearman's correlations between the two fill volumes were always >0.94 and bias was always within the quality specifications. Conclusions Blood drawing into Vacutainer® Citrate Plus tubes at minimum fill volume does not clinically bias routine coagulation testing.

Effects of hemolysis, bilirubin, and lipemia interference on coagulation tests detected by two analytical systems.

INTRODUCTION: Interference on biological assays due to hemolysis, icterus, or lipemia (HIL) could represent a significant source of analytical errors leading to inaccurate interpretation of results. The aim of this study was to assess the HIL interference on prothrombin time (PT), activated partial thromboplastin time (aPTT), and fibrinogen, using mechanical and optical detection methods. METHODS: Control plasmas and plasmas from patients treated with vitamin K antagonists or unfractionated heparin, with or without HIL, were performed on two analytical detection systems in order to identify potential analytical biases. Whether HIL lead to significant biological interferences was also evaluated, and a cutoff point for HIL-induced analytical bias was determined. RESULTS: Hemolysis influenced PT and aPTT when hemoglobin was at 5 and 1.5 g/L in plasma, respectively. At 1.8 g/L, a positive relationship was found between the bias and the hemoglobin supernatant level only for fibrinogen measurement, using optical detection. For icteric interference, no significant bias was observed until a bilirubin concentration of 30 mg/dL. Lipamia (>500 mg/dL) led to analytical interference when using the optical analyzer. CONCLUSION: The present study detected analytical interferences such as lipemia (>500 mg/dL) on coagulation tests on the optical analyzer. We also found a biological impact on the results in case of hemolyzed sample: Fibrinogen was decreased when the hemoglobin level was superior to 1.8 g/L, PT was prolonged beyond 5 g/L, and aPTT was shortened beyond 1.5 g/L hemoglobin concentration, especially in patients treated with heparin. Above these thresholds, it is important not to give results that could influence the clinical decision.

Biological variation estimates of prothrombin time, activated partial thromboplastin time, and fibrinogen in 28 healthy individuals.

BACKGROUND: Although tests of global hemostasis prothrombin time (PT) and activated partial thromboplastin time (aPTT) should not be used for prediction of bleeding risk, these tests are often used by many clinicians in daily practice particularly as a preoperative screening test. Robust biological variation (BV) data are needed for safe clinical applications of these tests. In this study, a stringent protocol was followed to estimate the BV's for PT, aPTT, and fibrinogen levels. METHODS: Weekly blood samples were obtained from 28 healthy individuals (18 females, 10 males) during 10 weeks study period. All measurements were performed with Stago STA-R coagulation analyzer. Prior to coefficient of variation (CV)-analysis of variance (ANOVA), the data were assessed for normality, trends, outliers, and variance homogeneity. Sex-stratified within-individual (CVI ) and between-individual (CVG ) BV estimates were determined for PT, aPTT, and fibrinogen tests. RESULTS: No difference was found between male and female estimates of BV. The observed CVI and CVG estimates were found to be lower than those previously published. Only for fibrinogen, CVI was higher than CVG . CONCLUSION: Following a meticulous protocol, our study results provide up-to-date and more stringent BV estimates of global hemostasis tests.

Point-of-care testing for emergency assessment of coagulation in patients treated with direct oral anticoagulants.

BACKGROUND: Point-of-care testing (POCT) of coagulation has been proven to be of great value in accelerating emergency treatment. Specific POCT for direct oral anticoagulants (DOAC) is not available, but the effects of DOAC on established POCT have been described. We aimed to determine the diagnostic accuracy of Hemochron® Signature coagulation POCT to qualitatively rule out relevant concentrations of apixaban, rivaroxaban, and dabigatran in real-life patients. METHODS: We enrolled 68 patients receiving apixaban, rivaroxaban, or dabigatran and obtained blood samples at six pre-specified time points. Coagulation testing was performed using prothrombin time/international normalized ratio (PT/INR), activated partial thromboplastin time (aPTT), and activated clotting time (ACT+ and ACT-low range) POCT cards. For comparison, laboratory-based assays of diluted thrombin time (Hemoclot) and anti-Xa activity were conducted. DOAC concentrations were determined by liquid chromatography-tandem mass spectrometry. RESULTS: Four hundred and three samples were collected. POCT results of PT/INR and ACT+ correlated with both rivaroxaban and dabigatran concentrations. Insufficient correlation was found for apixaban. Rivaroxaban concentrations at <30 and <100 ng/mL were detected with >95% specificity at PT/INR POCT ≤1.0 and ≤1.1 and ACT+ POCT ≤120 and ≤130 s. Dabigatran concentrations at <30 and <50 ng/mL were detected with >95% specificity at PT/INR POCT ≤1.1 and ≤1.2 and ACT+ POCT ≤100 s. CONCLUSIONS: Hemochron® Signature POCT can be a fast and reliable alternative for guiding emergency treatment during rivaroxaban and dabigatran therapy. It allows the rapid identification of a relevant fraction of patients that can be treated immediately without the need to await the results of much slower laboratory-based coagulation tests. TRIAL REGISTRATION: Unique identifier, NCT02371070 . Retrospectively registered on 18 February 2015.

Revisión de los pacientes estudiados por coagulopatía en una unidad de Oncohematología / Review of patients studied for coagulopathy in a Hematology/Oncology unit

INTRODUCCIÓN: Los síntomas/signos indicativos de una coagulopatía son un motivo de consulta frecuente en las unidades de Hematología Pediátrica. Tanto la clínica como los antecedentes familiares son fundamentales para el diagnóstico. PACIENTES Y MÉTODOS: Estudio retrospectivo y descriptivo de los pacientes derivados a una consulta de Hematología Pediátrica de un hospital de tercer nivel por posible coagulopatía durante el año 2012. RESULTADOS: Se estudiaron 47 niños. El 61,7% no había presentado previamente sangrado. El motivo de derivación más frecuente fue un tiempo de tromboplastina parcial activada alargado sin hemorragia (42,5%); de estos, un 25% fue diagnosticado de una coagulopatía con riesgo real de sangrado. En los pacientes derivados por tiempo de tromboplastina parcial activada alargado con clínica hemorrágica se detecta una coagulopatía con riesgo real de sangrado con mayor frecuencia (41,7%). En los niños con antecedentes familiares de sangrado se diagnostica con más frecuencia una coagulopatía con riesgo real de sangrado: 37,5 vs. 14,3% (niños sin antecedentes familiares). Los diagnósticos han sido: sano (48,9%), enfermedad de von Willebrand tipo1 (19,1%), déficit de factor XII (19,1%), déficit de factor XI(4,2%), déficit de precalicreína/cininógeno de alto peso molecular (2,1%), déficit adquirido de factor X (2,1%) y déficit de factor IX (2,1%). CONCLUSIONES: Los antecedentes personales y familiares de sangrado orientan el diagnóstico de una coagulopatía. El motivo de derivación debería basarse en mayor medida en la clínica hemorrágica y no solo en un tiempo de laboratorio alterado. Los diagnósticos más frecuentes han sido enfermedad de von Willebrand tipo 1 y déficit de factor XII

INTRODUCTION: Symptoms/signs suggestive of coagulopathy is a frequent complaint in Pediatric Hematology units. Both the clinical and family history are essential for diagnosis. PATIENTS AND METHODS: Retrospective and descriptive study of patients referred to a Pediatric Hematology unit of a tertiary hospital for possible coagulopathy during 2012. RESULTS: A total of 47 children were studied, of whom 61.7% had not previously suffered bleeding. The most frequent reason for referral was an eloganted activated partial thromboplastin time without any hemorrhage (42.5%), of these, 25% were diagnosed of a coagulopathy with a real risk of bleeding. While patients referred due to an eloganted activated partial thromboplastin time with bleeding more frequently (41.7%) have a coagulopathy with a real risk of bleeding. Children with a family history of bleeding are diagnosed more frequently with a coagulopathy with a real risk of bleeding: 37.5% (family history) vs. 14.3% (without). The most frequent diagnoses were: healthy children (48.9%), von Willebrand type 1 disease (19.1%), factor XII deficiency (19.1%), factor XI deficiency (4.2%), prekalikrein/high molecular weight kininogen deficiency (2.1%), acquired deficiency of factor X (2.1%), and factor IXdeficiency (2.1%). CONCLUSIONS: A thorough personal and family bleeding history and physical examination are the first steps for a correct differential diagnosis. The reason for referral should be based more on clinical bleeding and not just on an abnormal coagulation time. The most frequent diagnoses were type 1 von Willebrand disease and factor XII deficiency

Performance Evaluation of the Sysmex CS-5100 Automated Coagulation Analyzer.

BACKGROUND: Coagulation testing is widely applied clinically, and laboratories increasingly demand automated coagulation analyzers with short turn-around times and high-throughput. The purpose of this study was to evaluate the performance of the Sysmex CS-5100 automated coagulation analyzer for routine use in a clinical laboratory. METHODS: The prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (APTT), fibrinogen (Fbg), and D-dimer were compared between the Sysmex CS-5100 and Sysmex CA-7000 analyzers, and the imprecision, comparison, throughput, STAT function, and performance for abnormal samples were measured in each. RESULTS: The within-run and between-run coefficients of variation (CV) for the PT, APTT, INR, and D-dimer analyses showed excellent results both in the normal and pathologic ranges. The correlation coefficients between the Sysmex CS-5100 and Sysmex CA-7000 were highly correlated. The throughput of the Sysmex CS-5100 was faster than that of the Sysmex CA-7000. There was no interference at all by total bilirubin concentrations and triglyceride concentrations in the Sysmex CS-5100 analyzer. CONCLUSIONS: We demonstrated that the Sysmex CS-5100 performs with satisfactory imprecision and is well suited for coagulation analysis in laboratories processing large sample numbers and icteric and lipemic samples.

Influence of dabigatran and rivaroxaban on routine coagulation assays. A nationwide Belgian survey.

The Belgian national External Quality Assessment Scheme performed a nationwide survey using lyophilised plasma samples spiked with dabigatran or rivaroxaban to demonstrate to the Belgian clinical laboratories how these drugs affect their routine coagulation assays prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen and antithrombin. Virtually all Belgian laboratories performing routine coagulation testing (189/192) participated in the survey. Both, dabigatran and rivaroxaban significantly prolonged the PT and aPTT in a concentration- and reagent-dependent manner. PT reagents were more influenced by rivaroxaban than by dabigatran and aPTT reagents more influenced by dabigatran than by rivaroxaban. Among PT reagents, Neoplastin R® was the most sensitive to rivaroxaban and Innovin® and Thromborel S® the least sensitive. Converting PT results to INR only increased the variability between reagents. Among aPTT reagents, Actin FSL® was the least sensitive to dabigatran while the other aPTT reagents showed slightly higher sensitivities. The presence of dabigatran led to falsely reduced fibrinogen concentrations when measured with a low thrombin concentration reagent. The presence of dabigatran caused an overestimation of the antithrombin level when measured with a thrombin-based activity assay and the presence of rivaroxaban an overestimation of the antithrombin level when measured with a FXa-based assay. Instrument-related differences were found for all tested parameters. In conclusion, this paper provides detailed information on the effect of dabigatran and rivaroxaban on routine coagulation assays as performed with a large number of reagent/instrument combinations.

A cartridge based sensor array platform for multiple coagulation measurements from plasma.

This paper proposes a MEMS-based sensor array enabling multiple clot-time tests for plasma in one disposable microfluidic cartridge. The versatile LoC (Lab-on-Chip) platform technology is demonstrated here for real-time coagulation tests (activated Partial Thromboplastin Time (aPTT) and Prothrombin Time (PT)). The system has a reader unit and a disposable cartridge. The reader has no electrical connections to the cartridge. This enables simple and low-cost cartridge designs and avoids reliability problems associated with electrical connections. The cartridge consists of microfluidic channels and MEMS microcantilevers placed in each channel. The microcantilevers are made of electroplated nickel. They are actuated remotely using an external electro-coil and the read-out is also conducted remotely using a laser. The phase difference between the cantilever oscillation and the coil drive is monitored in real time. During coagulation, the viscosity of the blood plasma increases resulting in a change in the phase read-out. The proposed assay was tested on human and control plasma samples for PT and aPTT measurements. PT and aPTT measurements from control plasma samples are comparable with the manufacturer's datasheet and the commercial reference device. The measurement system has an overall 7.28% and 6.33% CV for PT and aPTT, respectively. For further implementation, the microfluidic channels of the cartridge were functionalized for PT and aPTT tests by drying specific reagents in each channel. Since simultaneous PT and aPTT measurements are needed in order to properly evaluate the coagulation system, one of the most prominent features of the proposed assay is enabling parallel measurement of different coagulation parameters. Additionally, the design of the cartridge and the read-out system as well as the obtained reproducible results with 10 µl of the plasma samples suggest an opportunity for a possible point-of-care application.

Lesión pulmonar aguda como consecuencia de la transfusión de plasma fresco congelado en un paciente con déficit de factor XII / Acute lung injury as a consequence of fresh frozen plasma administration in a patient with factor XII deficiency

Los test de coagulación son, junto con el hemograma, las pruebas de laboratorio más solicitadas a los pacientes antes de una intervención quirúrgica. El tiempo de tromboplastina parcial activado (TTPA) cuantifica la vía intrínseca y común de la coagulación, incluyendo los factores XII, XI, IX, VIII, X, V y II. El déficit de factor XII se asocia a un alargamiento del TTPA y a un aumento de los fenómenos tromboembólicos sin incrementar el riesgo de hemorragia intraoperatoria. A un varón de 20 años con déficit de factor XII se le administraron dos unidades de plasma fresco congelado ante un valor de TTPA de 100 segundos con intención de corregir una posible alteración de la coagulación ante una cirugía de urgencias y el temor de un sangrado intraoperatorio. A la hora del inicio de la trasfusión el paciente desarrolló un cuadro de lesión pulmonar aguda compatible con el diagnóstico de TRALI (transfusión related acute lung injury). La cirugía trascurrió con normalidad y el paciente permaneció ingresado en la unidad de reanimación 72 horas durante las que precisó soporte respiratorio. Ante una prolongación del TTPA en ausencia de sangrado se debe descartar la presencia de un anticoagulante circulante inespecífico, un déficit de factor XI, un déficit de factor XII y un déficit de factor VIII asociado a la enfermedad de von Willebrand. Por lo tanto, en el caso que presentamos fue innecesaria la administración de hemoderivados al paciente pudiendo tener consecuencias tan graves como la que presentó, la aparición de una lesión pulmonar aguda asociada a la trasfusión (AU)

Along with the complete blood count, the coagulation tests are those most demanded before a surgical procedure. The activated partial thromboplastin time (APPT) quantifies the intrinsic and common coagulation pathways, including factors XII, XI, IX, VIII, X, V and II. Factor XII deficiency is associated with a prolonged APPT and an increase in thromboembolic phenomena, without increasing the intraoperative bleeding risk. A 20 year old man with factor XII deficiency was receiving two units of fresh frozen plasma because of an APPT of 100 seconds, with the intention of normalizing it before an urgent surgery procedure, and the fear of intraoperative bleeding. An hour after starting the transfusion the patient developed an acute lung injury (ALI) compatible with the diagnosis of a transfusion related acute lung injury (TRALI). The surgery continued without complications, and the patient was admitted to the resuscitation unit for 72h, needing respiratory support. If the APTT is prolonged in the absence of bleeding, the presence of a non-specific circulating anticoagulant, a deficiency of factor XI, XII and VIII (associated to Von Willebrand disease) must be ruled out. Therefore, in the case presented here, the administration of hemoderivatives was unnecessary and can have consequences as serious as the one that the patient presented, a transfusion related acute lung injury (AU)

Evaluation of the GEM®PCL Plus point-of-care device for neonatal coagulation assessment: an observational study on cord blood.

INTRODUCTION: Point of care devices (POCT) are used for coagulation evaluation in adults. Reduced blood volumes and the direct use of whole blood allow studies when venous puncture is difficult, such as in newborns. Elimination of sample transport is attractive for use in emergencies and intensive care. OBJECTIVE: To prospectively compare neonatal coagulation parameters measured by the GEM®PCL POCT versus a central laboratory. MATERIALS AND METHODS: Prothrombin Time (PT) and activated Partial Thromboplastin Time (aPTT) were performed on whole cord blood (POCT) and plasma (central laboratory) collected from consecutive newborns at Geneva University Hospitals. Agreement was assessed with a Bland & Altman plot and intra-class correlation coefficient (ICC) in 213 newborns cord blood; intra-assay variability (repeatability) was assessed using ICC and coefficient of variation (CV). RESULTS: 189 samples were available for the agreement analysis, 24 were excluded for technical problems. The 95% limits of agreements in the Bland & Altman plot ranged from -5.6 to 11.6 and from -39.6 to 11.6seconds for the PT and aPTT, respectively. The ICC between the two methods was 0.28 (CI 95% 0.06 to 0.47) for PT and 0.20 (CI 95% -0.06 to 0.42) for aPTT. Repeatability (ICC) on the 43 eligible samples was 0.46 (CI 95% 0.19 to 0.67) for PT and 0.52 (CI 95% 0.26 to 0.71) for aPTT. The CV was 10.6% and 12% for PT and aPTT, respectively. CONCLUSIONS: In newborn cord blood, PT and aPTT measurements with the GEM®PCL POCT had poor agreement with the central laboratory and poor repeatability.

Evaluation and performance characteristics of the Q Hemostasis Analyzer, an automated coagulation analyzer.

The Q Hemostasis Analyzer (Grifols, Barcelona, Spain) is a fully-automated random-access multiparameter analyzer, designed to perform coagulation, chromogenic and immunologic assays. It is equipped with a cap-piercing system. The instrument was evaluated in a hemostasis laboratory of a University Hospital with respect to its technical features in the determination of coagulation i.e. prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin time, fibrinogen and single coagulation factors V (FV) and VIII (FVIII), chromogenic [antithrombin (AT) and protein C activity] and immunologic assays [von Willebrand factor antigen (vWF:Ag) concentration], using reagents from the analyzer manufacturer. Total precision (evaluated as the coefficient of variation) was below 6% for most parameters both in normal and in pathological ranges, except for FV, FVIII, AT and vWF:Ag both in the normal and pathological samples. No carryover was detected in alternating aPTT measurement in a pool of normal plasma samples and in the same pool spiked with unfractionated heparin (>1.5 IU/mL). The effective throughput was 154 PT, 66 PT/aPTT, 42 PT/aPTT/fibrinogen, and 38 PT/aPTT/AT per hour, leading to 154 to 114 tests performed per hour, depending of the tested panel. Test results obtained on the Q Hemostasis Analyzer were well correlated with those obtained on the ACL TOP analyzer (Instrumentation Laboratory), with r between 0.862 and 0.989. In conclusion, routine coagulation testing can be performed on the Q Hemostasis Analyzer with satisfactory precision and the same apply to more specialized and specific tests.

Hemofilia A adquirida posparto: guía de diagnóstico y tratamiento a raíz de un caso clínico / Postpartum adquired A Hemophilia: guide to diagnosis and treatment apropos of a case report

La hemofilia A adquirida (HAA) posparto es una entidad extremadamente infrecuente (100 casos descritos en la literatura) y potencialmente grave. Se caracteriza por la aparición de anticuerpos antifactor viii (FVIII) circulante, que producen clínica hemorrágica en el puerperio, sin afectar al feto. Por lo general, los anticuerpos desaparecen espontáneamente en las primeras semanas o meses y no se reproduce en gestaciones posteriores. Pese a que el retraso en el diagnóstico puede ser fatal, la HAA posparto presenta buena respuesta al tratamiento procoagulante e inmunosupresor, siendo de mejor pronóstico que otras causas de hemofilia A. Por esta razón, ante síntomas como metrorragia incoercible sin causa obstétrica que lo justifique y signos como pruebas de coagulación alteradas, debemos sospechar esta enfermedad y realizar las pruebas diagnósticas de confirmación para instaurar sin demora el tratamiento sintomático y etiológico (AU)

Postpartum acquired hemophilia A is an extremely rare (100 cases in the literature) and potentially serious disease. Anti-circulating factor viii (FVIII) antibodies develop in the puerperium, leading to hemorrhagic symptoms without fetal danger. In general, the antibodies disappear spontaneously in the first few weeks or months after delivery and do not recur in subsequent pregnancies. Even though a delay in diagnosis can be fatal, postpartum hemophilia A has a good response to treatment and a better prognosis than other causes of hemophilia A. Consequently, it is important to suspect this disease in the presence of symptoms such as intractable vaginal bleeding without underlying obstetric disorders and signs such as abnormal coagulation tests. The correct diagnostic tests must be carried out to establish symptomatic and etiologic treatment without delay (AU)

Evaluation of the activated partial thromboplastin time assay for clinical monitoring of PEGylated recombinant factor VIII (BAY 94-9027) for haemophilia A.

Patients with haemophilia (PWH) are usually monitored by the one-stage activated partial thromboplastin time (aPTT) factor VIII (FVIII) assay. Different aPTT activators may affect clotting time (CT) and FVIII:C levels in patients treated with PEGylated FVIII. To evaluate the characteristics of PEGylated FVIII (BAY 94-9027) in various aPTT clotting assays, and to identify suitable aPTT reagents for monitoring BAY 94-9027 during the treatment of PWH, BAY 94-9027 and World Health Organization (WHO) 8th FVIII standards (WHO-8) were spiked into pooled and individual severe haemophilia A plasma at 1.0, 0.25 and 0.05 IU mL(-1) . Five commercial aPTT reagents widely used in clinical laboratories were compared and evaluated for BAY 94-9027 activity in plasma from PWH. BAY 94-9027 and WHO-8 bestowed similar CT and excellent precision when ellagic acid (SynthAFax, Dade Actin, and Cephascreen) aPTT reagents were used. In contrast, BAY 94-9027 showed significantly prolonged CT and poor precision compared with WHO-8 using silica aPTT reagents (APTT-SP and STA PTT 5). Furthermore, free 60-kDa polyethylene glycol (PEG), used for the conjugation of FVIII, showed a dose-dependent prolongation of CT in the APTT-SP assay. There was no effect on the SynthAFax-APTT, prothrombin time, or FXIa-initiated thrombin generation assay, demonstrating that the PEG moiety on FVIII has no general effect on the coagulation cascade. In summary, ellagic aPTT reagents (SynthAFax, Dade Actin, and Cephascreen) are most suitable for evaluating potency of BAY 94-9027 and should be the preferred aPTT reagents used in clinical laboratories for monitoring FVIII activity after infusion of BAY 94-9027 to PWH.

Impact of telavancin on prothrombin time and activated partial thromboplastin time as determined using point-of-care coagulometers.

Telavancin is approved in the United States, Canada, and Europe (At the time of submission, the telavancin European marketing authorization for nosocomial pneumonia was suspended until Theravance provides evidence of a new European Medicines Agency approved supplier) as an antibiotic to treat certain Gram-positive bacterial skin infections. Telavancin has been shown to prolong plasmatic prothrombin (PT) and activated partial thromboplastin (aPTT) clotting times in clinical diagnostic lab-based assays. In this study, we evaluated the potential for telavancin to prolong whole blood PT/International Normalized Ratio (INR) and aPTT tests on point-of-care (POC) instruments. Whole blood collected from 8 healthy subjects was supplemented with telavancin to final concentrations of 0, 10, 20, and 100 µg/ml. Final concentrations were selected to match trough, twice trough, and peak plasma levels following the approved 10 mg/kg dose. Four widely employed POC coagulation instruments were chosen to be representative of the POC platforms currently in use.. These systems were the Roche Coaguchek XS, the Abbott iSTAT, the ITC Hemochron SIG+, and the Alere INRatio2 POC devices. The PT/INR measured by the Coaguchek XS showed the greatest sensitivity to the presence of telavancin. The PT/INR measured by the Hemochron SIG+ and iSTAT were sensitive to telavancin but to a lesser extent. The INRatio2 was the least sensitive to the presence of telavancin when testing the whole blood PT/INR. Only the Hemochron SIG+ device was capable of measuring aPTT and showed a concentration-dependent increase in aPTT. This study supports the current recommendation that PT and aPTT monitoring be conducted immediately to the next dose of telavancin when coagulation parameters are tested using POC instrumentation.

Low intraindividual variability of activated partial thromboplastin time revealed in a population of 10,487 control individuals.

The activated partial thromboplastin time (aPTT) is a routine coagulation test that reflects the activities of multiple coagulation proteins. Given the known genetic elements underlying the different coagulation factor activities, a low intraindividual variability is expected in aPTT values, but has not been demonstrated in a large population. In this regard, we evaluated the intraindividual variability of aPTT by analyzing serial aPTTs from a large population. The study population consisted of control individuals who had three or more consecutive aPTT values at at least 6-month intervals at a single institution. The coefficient of variation of serial aPTT values was determined in each control individual, and the mean value of the coefficient of variations in the control population was calculated. The aPTT values from a total of 10,487 individuals [mean age 57 years (range 21-93 years); male-to-female ratio 1 : 0.9] were included. The mean value of the coefficient of variation of aPTTs in those individuals was 3.75%, which indicates a very low intraindividual variability. This is the first study to demonstrate a low intraindividual variability of aPTT in a large population. The result supports the previous notion that aPTT is a genetically determined parameter and has potential clinical implications.

Validation of the minimal citrate tube fill volume for routine coagulation tests on ACL TOP 500 CTS®.

INTRODUCTION: CLSI recommends a minimal citrate tube fill volume of 90%. A validation protocol with clinical and analytical components was set up to determine the tube fill threshold for international normalized ratio of prothrombin time (PT-INR), activated partial thromboplastin time (aPTT) and fibrinogen. METHODS: Citrated coagulation samples from 16 healthy donors and eight patients receiving vitamin K antagonists (VKA) were evaluated. Eighty-nine tubes were filled to varying volumes of >50%. Coagulation tests were performed on ACL TOP 500 CTS(®) . Receiver Operating Characteristic (ROC) plot, with Total error (TE) and critical difference (CD) as possible acceptance criteria, was used to determine the fill threshold. RESULTS: Receiving Operating Characteristic was the most accurate with CD for PT-INR and TE for aPTT resulting in thresholds of 63% for PT and 80% for aPTT. By adapted ROC, based on threshold setting at a point of 100% sensitivity at a maximum specificity, CD was best for PT and TE for aPTT resulting in thresholds of 73% for PT and 90% for aPTT. For fibrinogen, the method was only valid with the TE criterion at a 63% fill volume. CONCLUSION: In our study, we validated the minimal citrate tube fill volumes of 73%, 90% and 63% for PT-INR, aPTT and fibrinogen, respectively.

Mixing tests: diagnostic aides in the investigation of prolonged prothrombin times and activated partial thromboplastin times.

Mixing tests are a relatively simple procedure used in the hemostasis laboratory as a first-line investigation into the cause of an abnormal screening test, typically a prolonged activated partial thromboplastin time and/or a prolonged prothrombin time. The mixing test involves combining the test plasma with normal plasma, then repeating the screening test on the mixture to assess whether the clotting time becomes normal or remains prolonged. The primary purpose of a mixing test is to guide further investigations. When mixing test results "normalize," this suggests the test plasma is deficient in clotting factor(s) and thus specific factor assays can be performed to determine which are reduced. When the mixing test result does not "normalize," this suggests the presence of an inhibitor or other type of interference (e.g., the presence of an anticoagulant such as high-dose heparinoids), and so the laboratory needs to determine if this is a lupus anticoagulant or a specific coagulation factor inhibitor, or another type of inhibitor. Because these follow-up investigations are more costly and time-consuming than the basic screening tests, the appropriate performance and interpretation of mixing tests is advantageous for the laboratory. Moreover, the correct laboratory approach is also clinically relevant, as patient management is ultimately affected, and an incorrect interpretation may lead to inappropriate therapies being established. Components of a mixing test that can influence result interpretation include the sensitivity of the used screening reagents to various factor deficiencies and inhibitors, the source or composition of the normal plasma, and the setting of cutoffs for the formula used in expressing mixing test results. Numerous and differing criteria for mixing test interpretation have been suggested historically, which can lead to confusion as to which approach is the most appropriate. The use of differing criteria will also lead to differing interpretations regarding "normalization." For this pivotal reason, standardized mixing test procedures and a consistent set of validated interpretive criteria represent the most favorable approach to maximizing the utility of a mixing test, and ensure the most accurate diagnosis for investigated patients.