Factor VIII and IX assays for post-infusion monitoring in hemophilia patients: Guidelines from the French BIMHO group (GFHT).

Replacement therapy with plasma-derived or recombinant FVIII and FIX (pdFVIII/pdFIX or rFVIII/rFIX) concentrates is the standard of treatment in patients with haemophilia A and B, respectively. Measurement of factor VIII (FVIII:C) or factor IX (FIX:C) levels can be done by one-stage clotting assay (OSA) or chromogenic substrate assay (CSA). The French study group on the Biology of Hemorrhagic Diseases (a collaborative group of the GFHT and MHEMO network) presents a literature review and proposals for the monitoring of FVIII:C and FIX:C levels in treated haemophilia A and B patients, respectively. The use of CSA is recommended for the monitoring of patients treated with pdFVIII or rFVIII including extended half-life (EHL) rFVIII. Except for rFVIII-Fc, great caution is required when measuring FVIII:C levels by OSA in patients substituted by EHL-rFVIII. The OSA is recommended for the monitoring of patients treated with pdFIX or rFIX. Large discordances in the FIX:C levels measured for extended half-life rFIX (EHL-rFIX), depending on the method and reagents used, must lead to great attention when OSA is used for measuring FIX:C levels in patients substituted by EHL-rFIX. Data of most of recent studies, obtained with spiked plasmas, deserve to be confirmed in plasma samples of treated patients.

Four clinical and biological phenotypes in antiphospholipid syndrome: a cluster analysis of 174 patients with antinuclear antibody tests.

Introduction: Antiphospholipid syndrome (APS) is an autoimmune thrombotic disease with various systemic presentations. This study aimed to identify homogeneous groups of patients based on a non-supervised hierarchical cluster analysis and assess the rate of relapse associated with antinuclear antibodies (ANA). Methods: This retrospective observational study enrolled patients, over a 90-month period, who had APS as defined by the 2006 Sydney classification criteria, and for whom ANA workup was performed. Agglomerative unsupervised hierarchical clustering was conducted to classify patients into subgroups using 24 variables reflecting a range of clinical and biological baseline features associated with APS. Results: Hundred and seventy-four patients were included and were categorized into four phenotypes. Cluster 1 (n=73) associated mostly middle-aged men with risk factors for cardiovascular disease. Obstetrical APS with low-risk thrombosis made up cluster 2 (n=25). Patients with venous thromboembolism (VTE), microvascular findings and double/triple positive APL antibodies (50%) were represented in cluster 3 (n=33). Whereas cluster 4 (n=43) characterized a predominantly female subpopulation with positive ANA and systemic lupus (n=23) that exhibited a high thrombotic risk and more frequent relapses (n=38) (p<0.001). Conclusions: This study identified four homogenous groups of patients with APS listed as: i) cardiovascular and arterial risk, ii) obstetrical, iii) VTE and microvascular, and iv) ANA-positive APS. We found that ANA-positivity was associated with higher rates of relapse. Applying ANA status to classification criteria could constitute a novel approach to tailoring management for APS, based on phenotypic patterns and risk assessment.

F2c.*C20209T mutation in patients with a history of thrombosis: A case report, retrospective 2 site-results and review of the literature.

INTRODUCTION: G20210A (c.*97G>A) prothrombin gene variant, found in white population has been associated with an increased risk of venous thromboembolism (VTE). Other rare polymorphisms in F2 gene (C20209T) have been reported, more rare and touching black people, but its potential association with VTE remain uncertain. METHODS: About a 69 years-old Caucasian woman presenting an unprovoked deep venous thrombosis of the leg, we analyzed retrospectively 25.000 thrombophilia tests on a 11-year period of time (2007-2018), at Nice and Marseille University Hospitals, and performed extensive review of the literature. RESULTS: Genetic determination included a similar PCR protocol and sequencing. Twenty-one heterozygous cases out of 25.585 determinations (0.08%) was found. The C20209T mutation detected in our Caucasian patient is rare, with a frequency that differed from what was reported in the previous literature, mainly in non-Caucasian patients (Africans, Africans-Americans, and Caribbeans). One hundred and thirteen patients with this mutation have been described in the literature, of which only one homozygous. CONCLUSION: This study is the most important on C20209T mutation performed at present, allowing to precise its frequency and its potential role in venous thromboembolism.

APTT therapeutic range for monitoring unfractionated heparin therapy. Significant impact of the anti-Xa reagent used for correlation.

INTRODUCTION: Unfractionated heparin (UFH) therapy is monitored by using the anti-activated factor X (anti-Xa) activity, or the activated partial thromboplastin time (APTT), which remains the most widely used assay. One of the main advantages of anti-Xa relies on its hypothesized standardization, with a unique therapeutic range (0.30-0.70 IU/ml) for all reagents, whereas APTT is influenced by numerous preanalytical and analytical parameters not related to the anticoagulant activity of UFH. METHODS: The aim of this study was to compare the anti-Xa-correlated APTT therapeutic ranges calculated using different combinations of APTT (n = 4) and anti-Xa reagents (n = 4) in frozen citrated plasmas from 87 inpatients on UFH. RESULTS: The median APTT ratio ranged from 2.19 for the less sensitive to 3.23 for the most sensitive reagent, whereas the median anti-Xa activity was between 0.37 IU/ml and 0.57 IU/ml. The APTT therapeutic ranges calculated to correlate with anti-Xa activities between 0.30 and 0.70 IU/ml were found to be highly different from one combination of APTT reagent and analyzer to another. The same applied to the therapeutic range of a single APTT reagent calculated using different anti-Xa assays performed on the same analyzer, leading to a lack of agreement as to whether a sample was classified as subtherapeutic, therapeutic or supratherapeutic in 8.0% to 23.0% of the patients, with kappa coefficients between 0.908 and 0.753. CONCLUSIONS: These results suggest that the APTT therapeutic range calculated to correlate with anti-Xa activities between 0.30 and 0.70 IU/ml is influenced not only by the APTT reagent, but also by the anti-Xa reagent used for calculation.

Age-adjusted D-dimer cut-off levels to rule out venous thromboembolism in patients with non-high pre-test probability: Clinical performance and cost-effectiveness analysis.

BACKGROUND: As aging was found to be associated with increased D-dimer levels, the question arose whether D-dimer measurement was useful in the diagnostic strategy of venous thromboembolism (VTE) in elderly patients. AIM OF THE STUDY: To compare retrospectively the performance of six diagnostic strategies based on the three-level Wells scores and various cut-off levels for D-dimer, evaluated using the HemosIL D-Dimer HS 500 assay, in a derivation cohort of 644 outpatients with non-high pretest probability (PTP) of VTE. The clinical usefulness of the best-performing strategy was then confirmed in a multicenter validation study involving 1255 consecutive outpatients with non-high PTP. RESULTS: The diagnostic strategy based on the age-adjusted cut-off level calculated by multiplying the patient's age by 10 above 50 years was found to perform the best in the derivation study with a better sensitivity-to-specificity ratio than the conventional strategy based on the fixed cut-off level (500 ng/ml), a higher specificity and a negative predictive value (NPV) above 99%. Such an increase in test specificity was confirmed in the validation cohort, with the NPV remaining above 99%. Taking into account the local reimbursement rates of diagnostic tests, using this strategy led to a 6.9% reduction of diagnostic costs for pulmonary embolism and a 5.1% reduction for deep vein thrombosis, as imaging tests would be avoided in a higher percentage of patients. CONCLUSION: The diagnostic strategy of VTE based on the age-adjusted cut-off level for D-dimer in patients over 50 years was found to be safe, with NPV above 99%, and cost-effective.

Monitoring unfractionated heparin therapy: Lack of standardization of anti-Xa activity reagents.

INTRODUCTION: One of the main advantages of using anti-Xa instead of activated partial thromboplastin time in monitoring of unfractionated heparin (UFH) therapy relies on its hypothesized standardization, with a unique therapeutic range defined to be 0.30 to 0.70 IU/mL. The aim of the present study was to compare the inter-reagent agreement of anti-Xa activity. METHODS: Citrate tubes were obtained from 104 inpatients on UFH. Plasma samples were stored frozen in aliquots at -70°C before being shipped to three accredited coagulation laboratories to be evaluated for anti-Xa activity using their routine assay(s). Pooled normal plasmas spiked with dilutions of the 6th International Standard of UFH to achieve anti-Xa activities up to 1.0 IU/mL were evaluated using the same techniques. RESULTS: In the plasmas from patients on UFH, the median anti-Xa activity ranged from 0.37 IU/mL with one reagent to 0.57 IU/mL with another; results were in between (0.45 IU/mL) using two other reagents. Comparisons of results obtained using the different reagents demonstrated unacceptable bias up to 0.24 IU/mL between some reagents (41% difference). The concordance as whether anti-Xa activities measured using different reagents were within or outside the therapeutic range was between 0.411 and 0.939 (kappa). Similar discrepancy was demonstrated for anti-Xa activities when evaluating normal plasma spiked with the International Standard. A discrepancy of the same order of magnitude was demonstrated in the 2017 External Quality Assessment Program provided by the External Quality Control in Assays and Tests exercises. CONCLUSIONS: The reported discrepancy between test results obtained using different anti-Xa assays clearly suggests a lack of standardization of that assay with potentially significant impact on the patients' anticoagulation.

Monitoring unfractionated heparin therapy. 4 hour-stability of anti-Xa activity in unspun citrated tubes.

Current guidelines recommend performing laboratory tests aimed at monitoring unfractionated heparin (UFH) treatments within a delay not exceeding 1 to 2 h(s) after sampling when blood is collected into citrated tubes. As such a short delay could be an issue, we evaluated the potential impact of longer delays. For that purpose, two citrated tubes were obtained from patients on UFH: one was centrifuged and tested for anti-Xa activity and aPTT within 1 h after collection (T1 h) and one was stored for 4 h at room temperature (T4 h) before being processed. A total of 123 paired tubes were investigated. Anti-Xa activity was significantly lower at T4 h than at T1 h, with a mean bias, calculated according to Bland-Altman, of 0.05 IU/mL. Considering 0.30 to 0.70 IU/mL as the therapeutic range, there were 12 cases of discrepant test results (9.8%). Most of them being around the lower limit of the therapeutic range had no impact on patients' management. APTT was significantly shortened (p < 0.0001) at T4 h vs. T1 h, with a mean bias of -7.9 s. Considering anti-Xa correlated aPTT therapeutic range, 29 cases of discrepant test results (23.6%) were found, 10% would have induce dosage changes. The concordance between anti-Xa activities measured at T4 h and T1 h was excellent (kappa = 0.813) and good for aPTT (kappa = 0.661). In conclusion, extending the delay between blood collection and measurement of tests prescribed for monitoring UFH therapy up to 4 h was found to lead to a systematic reduction in both anti-Xa activity and aPTT in unspun citrated tubes. As changes at T4 h were limited and had few clinically relevance than the ones observed with aPTT testing, a 4 h-delay was found to be acceptable for anti-Xa activity. The maximum delay for aPTT should remain around 1-2 h as changes were more relevant.

High Prevalence of Acquired Thrombophilia Without Prognosis Value in Patients With Coronavirus Disease 2019.

Background Recent literature reports a strong thrombotic tendency in patients hospitalized for a coronavirus disease 2019 (COVID-19) infection. This characteristic is unusual and seems specific to COVID-19 infections, especially in their severe form. Viral infections can trigger acquired thrombophilia, which can then lead to thrombotic complications. We investigate for the presence of acquired thrombophilia, which could participate in this phenomenon, and report its prevalence. We also wonder if these thrombophilias participate in the bad prognosis of severe COVID-19 infections. Methods and Results In 89 consecutive patients hospitalized for COVID-19 infection, we found a 20% prevalence of PS (protein S) deficiency and a high (ie, 72%) prevalence of antiphospholipid antibodies: mainly lupus anticoagulant. The presence of PS deficiency or antiphospholipid antibodies was not linked with a prolonged activated partial thromboplastin time nor with D-dimer, fibrinogen, or CRP (C-reactive protein) concentrations. These coagulation abnormalities are also not linked with thrombotic clinical events occurring during hospitalization nor with mortality. Conclusions We assess a high prevalence of positive tests detecting thrombophilia in COVID-19 infections. However, in our series, these acquired thrombophilias are not correlated with the severity of the disease nor with the occurrence of thrombotic events. Albeit the strong thrombotic tendency in COVID-19 infections, the presence of frequent acquired thrombophilia may be part of the inflammation storm of COVID-19 and should not systematically modify our strategy on prophylactic anticoagulant treatment, which is already revised upwards in this pathological condition. Registration URL: https://www.clini​caltr​ials.gov; Unique identifier: NCT04335162.

Point-of-care versus central laboratory coagulation testing during haemorrhagic surgery. A multicenter study.

Delay in collecting coagulation test results from a central laboratory is one of the critical issues to efficiently control haemostasis during surgery. The aim of this multicenter study was to compare the performance of a point-of-care (POC) device (CoaguChek Pro DM) with the central laboratory-based coagulation testing during haemorrhagic surgery. For this purpose, 93 patients undergoing major surgical procedure were prospectively included in three centers. Blood was drawn from all patients before surgical incision and from most patients during surgical procedure after a blood loss of 25% or more was observed. When expressed in activity percentage, POC-based prothrombin time (PT) was in good agreement with central laboratory test result with coefficient of correlation in the range from 0.711 to 0.960 in the three centers. Comparison was less conclusive when PT was expressed in seconds or as the patient-to-control ratio and for activated partial thromboplastin time, with significantly shorter clotting times and lower ratios obtained on the POC device. On-site PT (in activity percentage) monitoring would have induced no significant change in fresh frozen plasma (FFP) transfusion in patients when compared to central laboratory monitoring. Test results were obtained in less than 5 minutes when performed using the POC device versus a median turnaround time of 88 minutes (range: 29-235 minutes) when blood collection tubes were sent to the central laboratory. These results suggest that, in providing a rapid answer, POC-based monitoring of PT (in percentage) using the CoaguChek device could be validly used in patients undergoing haemorrhagic surgical procedures.

Evaluation of a rapid qualitative immuno-chromatography D-dimer assay (Simplify D-dimer) for the exclusion of pulmonary embolism in symptomatic outpatients with a low and intermediate pretest probability. Comparison with two automated quantitative assays.

The performance of a rapid qualitative solid-phase immuno-chromatography-based D-dimer assay (Simplify D-dimer) for diagnosing pulmonary embolism (PE) was evaluated in 469 outpatients with a low or intermediate pretest probability. They were referred to the emergency department of a university hospital during a 4-month period. Test results were compared to those of two automated quantitative assays. Simplify D-dimer assay result was positive in all 47 patients in whom the diagnosis of PE was retained and in 219 of the 422 patients without PE (51.2%), leading to a sensitivity of 100% (95%CI, 92.5 to 100%), a specificity of 48.8% (95%CI, 44.0 to 53.6%) and a negative predictive value (NPV) of 100% (95%CI, 98.2 to 100%). These results compared favorably with those of the Vidas D-dimer New assay [sensitivity=100% (95%CI, 92.5 to 100), specificity=49.8% (95%CI, 45.0 to 54.6%) and NPV=100% (95%CI, 98.3 to 100%)] and the STA-Liatest D-DI assay [sensitivity=100% (95%CI, 92.5 to 100%), specificity=48.1% (95%CI, 43.3 to 52.9%) and NPV=100% (95%CI, 98.2 to 100%)]. The inter-observer (n=2) variability was very good with 1.7% discordant readings and a kappa coefficient (K) value=0.97 (95%CI, 0.93 to 1.00). In conclusion, the Simplify D-dimer assay could be a valuable tool for ruling out PE in out-patients but a specific learning course of those having to work with is required in order to minimize the number of ambiguous reading and to overcome the inter-observer variability.

[Factor IX assays in treated hemophilia B patients]. / Dosage de l'activité du facteur IX chez les patients hémophiles B substitués.

Replacement therapy with plasma-derived or recombinant FIX (pdFIX or rFIX) concentrates is the standard of treatment in patients with hemophilia B. The method predominantly used for measuring factor IX (FIX:C) levels is the one-stage clotting assay (OSA) but this method depends on the activated partial thromboplastin time (APTT) reagent and the coagulation analyzer used, and wide variations in the measurements of FIX recovery have been reported with some factor concentrates. The French study group on the biology of hemorrhagic diseases (a collaborative group of the GFHT and MHEMO network), presents a review of the literature and proposals for the monitoring of FIX:C levels in treated hemophilia B patients. The use of OSA calibrated with a plasma reference tested against the current FIX WHO International Standard is recommended for the monitoring of patients treated with pdFIX or rFIX. Chromogenic substrate assays (CSA) are adequate for the monitoring of patients treated with Rixubis®, but data available for Benefix® are currently too limited. For extended half-life rFIX (EHL-rFIX), large discordances in the FIX:C levels measured were evidenced, depending on the method and reagents used. Great attention is therefore required for measuring FIX:C levels by OSA in patients substituted by EHL-rFIX. Commercial kits for CSA are not equivalent, and although potentially useful, they are not validated for all EHL-rFIX. Most of recent studies reported data obtained with spiked plasmas, which deserve to be confirmed on plasma samples collected in treated patients.

[Factor VIII assays in treated hemophilia A patients]. / Dosage de l'activité du facteur VIII chez les patients hémophiles A substitués.

Replacement therapy with plasma-derived or recombinant FVIII (pdFVIII or rFVIII) concentrates is the standard of treatment in patients with hemophilia A. The reference method used for measuring factor VIII (FVIII:C) levels in patients treated by FVIII concentrates is the chromogenic substrate assay (CSA). However, the one-stage clotting assay (OSA) is predominantly used in current clinical practice, but this method depends on the activated partial thromboplastin time (APTT) reagent and the coagulation analyzer used, and wide variations in the measurements of FVIII recovery have been reported with some factor concentrates. The French study group on the biology of hemorrhagic diseases (a collaborative group of the GFHT and MHEMO network) presents a review of the literature and proposals for the monitoring of FVIII:C levels in treated hemophilia A patients. The use of CSA calibrated with a plasma reference tested against the current FVIII WHO (World Health Organization) International Standard is recommended for the monitoring of patients treated with pdFVIII or rFVIII including extended half-life (EHL) rFVIII. OSA are adequate for the monitoring of patients treated with pdFVIII or with most of rFVIII concentrates. However, preliminary comparison with CSA is mandatory before measuring FVIII:C by OSA in patients treated by Refacto AF®. For rFVIII-EHL, OSA are only acceptable for Elocta®. Great caution is therefore required when measuring FVIII:C levels by OSA in patients substituted by other EHL-rFVIII. Indeed, most of recent studies reported data obtained with spiked plasmas, which deserve to be confirmed on plasma samples collected in treated patients.

An abnormal ProC Global test result is associated with an increased risk of venous thromboembolism independent of test sensitivity for protein C pathway abnormalities.

The ProC Global assay is a clotting assay primarily developed to globally evaluate the functionality of the protein C (PC) pathway. It was shown to lack both sensitivity and specificity for PC pathway abnormalities, i.e. factor V Leiden mutation, PC and PS deficiency. The hypothesis that an abnormal test result could be associated with venous thromboembolism (VTE) was evaluated in a case-control study. The proportion of reduced response was significantly higher in cases than in controls [n = 71/139 (51.1%) vs. n = 28/147 (19.0%); p < 0.0001] and the same applied after exclusion of those subjects with any PC pathway abnormality [n = 53/119 (44.5%) vs. n = 25/143 (17.5%); p < 0.0001]. An abnormal ProC Global assay result was significantly associated with thrombosis both in the whole population (odds ratio [OR]=4.44, 95% confidence interval [CI]=2.61-7.53) and in those subjects without any PC pathway abnormality (OR = 3.70, 95%CI = 2.16-6.66). The ProC Global assay result was significantly lower in cases with idiopathic VTE than in those with secondary VTE (p < 0.0001). No significant difference was observed when cases were classified according to the presence or absence of recurrent episodes. Moreover, a reduced response was found to be associated with VTE both in subjects with normal or elevated factor VIII (FVIII) level. In vitro, FVIII was found to play a critical role in the ProC Global assay result as suggested by the significant trend toward decreasing response with increasing FVIII levels. In conclusion, our results suggest that an abnormal ProC Global assay result is associated with an increased risk of VTE independently of its sensitivity for PC pathway abnormalities.

A new plastic collection tube made of polyethylene terephtalate is suitable for monitoring traditional anticoagulant therapy (oral anticoagulant, unfractionated heparin, and low molecular weight heparin).

To improve the safety of blood collection, plastic tubes have been developed but various interactions with the coagulation system and/or antithrombotic drugs were reported with the first generation of such tubes. The aim of this multicentre study was to compare hemostasis test results measured in evacuated plastic tubes made of polyethylene terephtalate (VenoSafe, Terumo Europe) and in siliconized glass tubes containing the same citrate concentration (0.129 M). In addition, the impact of aging of the plastic tube was investigated by collecting blood samples in tubes at 8 months and at 1 month before expiry. Blood was drawn in 3 centres from untreated patients (n=269), patients on oral anticoagulant treatment (OAT, n=221), and patients treated with either unfractionated heparin (UFH, n=73) or a low molecular weight derivative (LMWH, n=48). Prothrombin time (PT) or INR, activated partial thromboplastin time (APTT) and anti-FXa activity were locally performed, when applicable. In untreated patients and in patients on OAT, PT and APTT values were found statistically shorter (p<0.05) when evaluated in plastic tubes than in glass tubes, except when PT was evaluated using a human thromboplastin. Surprisingly, significantly longer APTT and higher anti-FXa activities were obtained when blood from patients on UFH was drawn in plastic than in glass tubes. However, none of the differences had any clinical relevance (Bland-Altman analysis). In patients on anticoagulant treatment, there was no effect of aging of the plastic tubes. These results suggest that the plastic tube VenoSafe is suitable for coagulation testing both in untreated subjects and more interestingly in patients on traditional anticoagulant therapy during the whole shelf life indicated by the manufacturer.

Evaluation and performance characteristics of the automated coagulation analyzer ACL TOP.

INTRODUCTION: The ACL TOP is a fully-automated random-access multiparameter coagulation analyzer equipped with a photo-optical clot-detection unit. It is designed to perform coagulation, chromogenic and immunologic assays with continuous loading capabilities for samples, reagents and disposables. MATERIALS AND METHODS: The instrument was evaluated in a coagulation laboratory of a university hospital with respect to its technical features in the determination of routine coagulation (prothrombin time, activated partial thromboplastin time, fibrinogen and single coagulation factor levels), chromogenic (anti-activated factor X, antithrombin and protein C activities) and immunologic assays (free protein S and von Willebrand factor antigen concentrations). RESULTS: Using fresh and lyophilized plasma samples, the intra-assay and inter-assay coefficients of variation were below 5% for most of the parameters both in the normal and in the pathological ranges. For clotting assays performed at 671 nm, no significant interference could be demonstrated with hemolytic, icteric and lipemic samples as demonstrated by results similar to those obtained using a mechanical clot-detection-based analyzer (STAR). No sample carryover was detected in measuring alternatively heparinized (1.0 IU/mL unfractionated heparin) and normal plasma samples. The results of the different coagulation, chromogenic and immunologic assays obtained on the ACL TOP were well correlated with those obtained on the STAR analyzer with the correlation coefficient (r) in the range from 0.876 to 0.990. CONCLUSIONS: Our results demonstrated that using the ACL TOP analyzer, routine hemostasis testing can be performed with satisfactory precision and the same applied to more specialized and specific tests such as single factor activity or antigen concentration.

Evaluation of the automated coagulation analyzer Sysmex CA-7000.

The Sysmex CA-7000 is a fully automated multiparameter hemostasis analyzer equipped with a photo-optical clot detection unit and a cap-piercing system. It is designed to perform coagulation tests as well as chromogenic and immunologic assays. It was evaluated in a coagulation laboratory of a university hospital with respect to its technical characteristics in the determination of routine coagulation (prothrombin time, activated partial thromboplastin time, fibrinogen and single coagulation factors), chromogenic (antithrombin, and anti-FXa activity) and immunologic assays (von Willebrand factor). The intra-assay and inter-assay coefficients of variation (CV) were below 5% for most parameters both in the normal and in the pathological range (exceptions: intra-assay CV=5.2% for the fibrinogen and 5.1% for antithrombin in the low range of concentrations; and inter-assay CV=5.7% and 7.2% for clotting factors V and VII levels in the normal ranges, and in the range from 6.1% to 7.8% for anti-FXa activity). No significant interference could be demonstrated with hemolytic and icteric samples as demonstrated by results similar to those obtained using a mechanical clot detection-based analyzer (STAR). No carryover was detected in alternating measurements of heparinized (1.0 IU/mL unfractionated heparin) and normal plasma samples. The results of the different coagulation, chromogenic and immunologic assays obtained with the CA-7000 analyzer were well correlated with those obtained on the STAR analyzer (r in the range from 0.885 to 0.990). Our results demonstrated that using the CA-7000 analyzer, routine coagulation testing can be performed with satisfactory precision and the same applied to more specialized and specific tests such as single factor activity or antigen concentration.

Multicenter evaluation of a bilayer polymer blood collection tube for coagulation testing: effect on routine hemostasis test results and on plasma levels of coagulation activation markers.

We compared the results of different hemostasis tests obtained in an evacuated bilayer polymer tubes (Vacuette, Greiner Bio-One) and in a siliconized glass tubes containing the same citrate concentrations (0.109 M and 0.129 M). For that purpose, blood was collected in five centers from 60 untreated patients and from patients on oral anticoagulant (n = 168), unfractionated heparin (n = 111) or a low molecular weight derivative (n = 108). Test results obtained in polymer tubes were not significantly different from those in glass tubes, except for INR when a high ISI thromboplastin was used (p < 0.0001 for tubes containing 0.129 M sodium citrate) and for APTT (p < 0.05 for both citrate concentrations). However, these differences had no clinical relevance (Bland-Altman analysis). In addition, no effect of aging of the polymer tubes on the test results could be demonstrated. The plasma levels of F1+2 and TAT, measured in a subset of 30 untreated patients, were significantly lower when blood was collected in polymer than in glass tubes, for both citrate concentrations. These results suggest that samples collected into the Vacuette polymer tubes allow accurate routine hemostasis testing both in untreated patients and in patients on traditional anticoagulant treatment during the whole shelf-life indicated by the manufacturer.