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Diagnostic algorithms for deep vein thrombosis (DVT) include D-dimer for its high negative predictive value, thus reducing the need for imaging. Small thrombi may be associated with low D-dimer levels, increasing false negatives.To assess the sensitivity and thus the false negative rates of standard and age-adjusted D-dimer cut offs for isolated distal DVT (IDDVT) in outpatients.We enrolled consecutive outpatients with suspected DVT of the lower limbs referring to our vascular emergency department from 2009 to 2018. Patients underwent D-dimer testing (STA, Stago, cut-off: 500 μg/L), pretest clinical probability (PTP) evaluation and complete compression ultrasonography. Follow-up was 3 months.Among 3948 patients (M:1554-39%, median age 69), 486 proximal DVTs (12.3%) and 348 IDDVTs (8.8%) were diagnosed. Median D-dimer was higher in proximal than IDDVT (3960 vs 1400 μgr/L; p = 0.001). The false negative rate of the standard D-dimer cut-off was 2% (95%CI: 0.8-3.2%) for proximal DVT and 14.7% (95% CI: 11-81%) for IDDVT. The false negative rate of the age-adjusted cut-off was 4.9% (3-7%) for proximal DVT and 19.5% (95% CI: 15.4-24.7%) for IDDVT.Small calf thrombi are associated with low D-dimer levels, and age-adjusted D-dimer may be below the cut-off more frequently in subjects with IDDVT than standard cut-off D-dimer, although such D-dimer levels might exclude IDDVT that require treatment.

Low attention has generally been dedicated to the influence of clinical presentation, extent of venous thrombosis and presence of residual vein obstruction (RVO) on the decision about the duration of secondary prophylaxis after a first venous thromboembolism (VTE).This study aimed at investigating the role of the mentioned VTE characteristics on the therapeutic decision using the information collected in the international, prospective, observational WHITE study.1240 patients were recruited by 79 clinical centers in 7 countries (China, Czechia, Poland, Portugal, Russia, Slovakia, and Tunisia). 35 patients had as index event a pulmonary embolism (PE) without a deep vein thrombosis (DVT), and all continued anticoagulation. We focused on the 1205 subjects with DVT. The treatment decision differed among countries; altogether, more than 85% of patients with proximal (with or without distal) DVT continued a prophylactic treatment with anticoagulants, or antithrombotics; 34% of patients with isolated distal DVT stopped treatment, and more than 85% of patients with a PE associated to a DVT continued treatment. At multivariable analysis, the presence of proximal DVT, signs of post-thrombotic syndrome (PTS), residual vein obstruction (RVO), maintenance180 days and concomitant diseases was associated with increased probability to continue secondary prophylaxis.The presentation as proximal DVT (with or without PE) or isolated PE influenced the treating physicians' decision in favor of extension of secondary prophylaxis, together with the presence of concomitant diseases and local conditions which may increase the risk of post-thrombotic syndrome.

The decision on treatment after a first venous thromboembolism (VTE) to prevent recurrences may be influenced by many factors. The prospective, observational, WHITE study aimed to analyze how this issue was tackled in every-day clinical practice in various countries, which have sensibly different socio-economic conditions and healthcare systems. Doctors active in 79 Internal or Vascular clinical centers in 7 countries (China, Czechia, Poland, Portugal, Russia, Slovakia, and Tunisia) enrolled VTE patients after the maintenance treatment phase. The present report analyzed information, collected in the central database, regarding the baseline characteristics, index events, type and duration of anticoagulant therapy and decision on post-maintenance treatment. From April 2018 to December 2020, 1240 patients were enrolled, 58% with an unprovoked index event. Direct oral anticoagulants (DOACs) were used in > 85% of all cases in China, Poland, Portugal, Russia and Czechia, in 52% in Slovakia and in no patient in Tunisia. The maintenance anticoagulation lasted in average approximately 6 months. Altogether, anticoagulation was stopped in 20%, extended in about 50%, regardless of whether the event was unprovoked or provoked and shifted to antithrombotics (mainly sulodexide or aspirin) in the remaining patients. In conclusion, some differences in VTE patient management were found between countries. The provoked/unprovoked nature of the index event, instead, was not the prevalent criterion to drive the decision on extension of anticoagulation, without large variations between countries. DOACs were the most widely used anticoagulant drugs, whereas > 25% of patients received antithrombotic drugs instead of anticoagulants as extended treatment. Supplementary Information The online version contains supplementary material available at 10.1007/s11739-021-02765-1.

Introduction: Co-administration of enoxaparin and a direct oral factor Xa inhibitor (xabans: apixaban, edoxaban, rivaroxaban) could give rise to the problem of overlapping the anti-Xa activity when measuring direct oral anticoagulant (DOAC) levels. We aimed to evaluate in vitro the degree of the interference of increasing enoxaparin concentrations on xaban plasma levels measured by different chromogenic anti-Xa assays with drug-specific calibrators and controls. Methods: Seven plasma samples were spiked with apixaban, edoxaban, or rivaroxaban at fixed concentration, and enoxaparin at increasing concentrations (0, 0.125, 0.250, 0.50, 1.0, 1.50, and 2.0IU/mL). The evaluated chromogenic assays were as follows: Biophen DiXaI and Biophen Heparin LRT (Hyphen BioMed), Berichrom Heparin and Innovance Heparin (Siemens), STA-Liquid Anti-Xa (Stago Diagnostics), Technochrom anti-Xa (Technoclone), and HemosIL Liquid Anti-Xa (Werfen). Results: The presence of enoxaparin caused increased DOAC levels, with over-estimation depending on the anti-Xa assay and on the heparin concentration in the sample. The smallest over-estimation was in the sample with enoxaparin 0.125IU/mL and the greatest in the sample with enoxaparin 2.0IU/mL (0%, 3.1%, and 7.4% vs 583.8%, 526.1%, and 415.2% for apixaban, edoxaban, and rivaroxaban, respectively). Biophen DiXaI showed lower interference compared to other methods (maximum over-estimation in the presence of enoxaparin 2.0IU/mL: 56.4% dosing rivaroxaban by Biophen DIXaI vs 583.8% dosing apixaban by Berichrom Heparin). Conclusion: The presence of enoxaparin interferes with xabans measurement by chromogenic anti-Xa assays causing falsely elevated DOAC levels, the over-estimation being dependent on the anti-Xa assay and on the heparin concentration in the sample.

Essentials Between-lab variations of cut-off values in lupus anticoagulant detection are unknown. Cut-off values were calculated in 11 labs each testing plasma from 120 donors with 3 platforms. Major variation was observed even within the same platform. Cut-off values determined in different labs are not interchangeable. SummaryBackground Cut-off values for interpretation of lupus anticoagulant (LA) detection are poorly investigated. Aims (i) To assess whether results from healthy donors were normally distributed and (ii) the between-laboratories differences in cut-off values for screening, mixing and LA confirmation when calculated as 99th or 95th centiles, and (iii) to assess their impact on the detection rate for LA. Methods Each of 11 laboratories using one of the three widely used commercial platforms for LA detection was asked to collect plasmas from 120 healthy donors and to perform screening, mixing and LA confirmation with two methods (activated partial thromboplastin time [APTT] and dilute Russell viper venom [dRVV]). A common set of LA-positive or LA-negative freeze-dried plasmas was used to assess the LA detection rate. Results were centralized (Milano) for statistical analysis. Results and conclusions (i) Clotting times or ratios for healthy subjects were not normally distributed in the majority of cases. The take-home message is that cut-off values should be determined preferably by the non-parametric method based on centiles. (ii) There were relatively large inter-laboratory cut-off variations even within the same platform and the variability was marginally attenuated when results were expressed as ratios (test-to-normal pooled plasma). The take-home message is that cut-off values should be determined locally. (iii) There were differences between cut-off values calculated as 99th or 95th centiles that translate into a different LA detection rate (the lower the centile the greater the detection rate). The take-home message is that cut-off values determined as the 95th centile allow a better LA detection rate.

Introduction: To measure direct factor Xa inhibitor (apixaban, edoxaban, rivaroxaban) concentrations, dedicated chromogenic anti-Xa assays are recommended as suitable methods to provide rapid drug quantification. Moreover, the high-performance liquid chromatography with ultraviolet detection (HPLC-UV) is reported as a reliable quantitative technique. We investigated seven anti-Xa assays and an HPLC-UV method for measurement of apixaban and rivaroxaban levels in patients enrolled in the START-Register. Methods: A total of 127 apixaban and 124 rivaroxaban samples were tested by HPLC-UV and the following anti-Xa assays: Biophen DiXaI and Heparin LRT (Hyphen BioMed), Berichrom and Innovance Heparin (Siemens), STA-Liquid Anti-Xa (Stago Diagnostics), Technochrom anti-Xa (Technoclone), and HemosIL Liquid Anti-Xa (Werfen). Each method was performed in one of the participating laboratories: Bologna, Cremona, Florence, and Padua. Results: Our data confirmed the overestimation of apixaban and rivaroxaban levels by the antithrombin-supplemented anti-Xa method (Berichrom). Performances and reproducibility of the six anti-Xa assays not supplemented with antithrombin and the HPLC-UV method were good, with limits of quantification from 8-39ng/mL (apixaban) and 15-33ng/mL (rivaroxaban). The six chromogenic methods showed good concordances with the quantitative HPLC-UV [bias: −26.9-22.3ng/mL (apixaban), −11.3-18.7ng/mL (rivaroxaban)]. Higher bias and wider range between limits of agreement were observed at higher concentrations [200ng/mL: bias −42.2-36.8ng/mL (apixaban) and −20.1-68.9ng/mL (rivaroxaban)]. Conclusion: Overall, the anti-Xa assays not supplemented with antithrombin and the HPLC-UV method proved to be suitable for apixaban and rivaroxaban quantification.

Introduction: Several specific assays are commercially available to determine dabigatran anticoagulant activity. Aims of this multicenter and multiplatform study were to compare five methods for dabigatran measurement and investigate their performances in the low concentration range. Methods: Dabigatran levels were analyzed in 295 plasma samples from patients enrolled in the START-Laboratory Register by the following methods using dedicated calibrators and controls: STA-ECA II (Diagnostica Stago), standard and low range Hemoclot Thrombin Inhibitors (Hyphen BioMed), Direct Thrombin Inhibitor Assay (Instrumentation Laboratory), Direct Thrombin Inhibitor Assay (Siemens), Technoclot DTI (Technoclone). Results: Methods showed variable agreement with the Hemoclot Thrombin Inhibitors assay used as reference test, with modest under- or overestimations (Bland-Altman bias from −17.3 to 4.0 ng/mL). Limits of detection and quantification varied depending on the assay (4-52 and 7-82 ng/mL, respectively). Between-run precision and accuracy were good for all methods for both quality control levels. Assay's repeatability assessed at very low dabigatran concentrations (from 10 to 60 ng/mL) was also acceptable, variability generally increased at lower drug levels. Conclusion: The five dabigatran-specific assays evaluated in this study provided reliable assessment of dabigatran plasma levels, although showing different performances. © 2018 The Authors. International Journal of Laboratory Hematology Published by John Wiley & Sons Ltd

Heparin-induced thrombocytopenia (HIT) is a prothrombotic condition and it is associated with increased in vivo thrombin generation that needs to be treated with non-heparin anticoagulants such as direct thrombin inhibitors (DTIs). DTIs require parenteral administration and are associated with a non negligible risk of major bleeding. We describe a case of HIT treated with rivaroxaban, a direct oral factor Xa inhibitor which could be used to inhibit the generation of thrombin, instead of DTIs. A 68 year-old man with a thrombosis confined to the internal gastrocnemius and soleal veins developed HIT during enoxaparin 80 mg twice a day. Enoxaparin was stopped and rivaroxaban 20 mg once a day was started. Platelet count returned to base line after 6 days from enoxaparin withdrawal. After 3 months rivaroxaban was stopped and the patient had an uneventful course. This case report supports the hypothesis that rivaroxaban may be candidate for treatment of HIT, and larger studies are justified.

Intracranial atherosclerotic disease (ICAD) is responsible for at least 10% of transient ischaemic attacks (TIA). Thrombin generation has been shown to be associated with several atherosclerotic conditions and may be relevant in the pathogenesis of TIA from ICAD. BACKGROUND: Intracranial atherosclerotic disease (ICAD) is responsible for at least 10% of transient ischaemic attacks (TIA). Thrombin generation has been shown to be associated with several atherosclerotic conditions and may be relevant in the pathogenesis of TIA from ICAD. OBJECTIVE: To evaluate the association between thrombin generation and ICAD in patients with TIA. MATERIALS AND METHODS: Consecutive patients with confirmed diagnosis of TIA by vascular neurologist were enrolled. Within 24h from diagnosis, all the patients underwent: blood samples including thrombin generation search, electrocardiography, brain CT scan, blood pressure (BP) measurement, supra-aortic echo-Doppler, transcranial Doppler (TCD) and standard echocardiogram. Thrombin generation was measured as endogenous thrombin potential (ETP) in platelet-rich plasma (PRP) and in platelet-poor plasma (PPP), in the presence and in the absence of thrombomodulin (TM). RESULTS: 120 patients (male 52.5%), aged 69±16years were enrolled. Ten patients on warfarin treatment had significantly lower ETP than the others. Among the remaining, ETP in the presence or absence of TM did not differ according to TOAST classification aetiology (large vessel vs. cardioembolic vs. lacunar vs. others). In PRP, ETP was similar in patients with ICAD and in those without (1748±160 vs. 1851±36nM·min, p=0.393), whereas, ETP measured in presence of thrombomodulin was higher in patients with than in those without ICAD (2045±99 vs. 1715±41nM·min, p=0.011). In PPP, ETP was similar in patients with ICAD and in those without, whereas thrombin peak was higher in patients with ICAD than in those without both in the presence (165±17 vs. 130±5nM, p=0.036) and in the absence of TM (178±19 vs. 142±5nM, p=0.037). CONCLUSION: ETP measured in presence of TM is enhanced in patients with ICAD, supporting that thrombomodulin-protein C pathways is relevant in TIA from ICAD. These hypothesis-generating data suggest that thrombin generation may be relevant in cerebral ischaemia from intracranial disease, and justify larger studies.

no abstract available

SummaryD-dimer and residual venous obstruction (RVO) have been separately shown to be risk factors for recurrent venous thromboembolism (VTE) after a first episode of unprovoked proximal deep-vein thrombosis (DVT). It was the objective of this study to assess the predictive value of D-dimer and residual vein obstruction (RVO), alone and in combination, for recurrence after provoked DVT of the lower limbs. A total of 296 consecutive patients with a first episode of symptomatic provoked proximal DVT were evaluated at a university hospital in Bologna, Italy. On the day of anticoagulation withdrawal (T0), RVO was determined by compression ultrasonography. D-dimer levels (cut-off: 500 ng/ml) were measured at T0 and after 30 ±10 days (T1). The main outcome was recurrent VTE during a two-year follow-up. D-dimer was abnormal in 11.6% (32/276) and 31% (85/276) of subjects at T0 and at T1, respectively. RVO was present in 44.8% (132/294) of patients. Recurrence rate was 5.1% (15/296; 95% confidence interval [CI]: 3–8%; 3% patient-years; 95% CI: 2–5 %). An abnormal D-dimer either at T0 or at T1 was associated with an adjusted hazard ratio (HR) for recurrence of 4.2 (95% CI:1.2–14.2; p=0.02) and 3.8 (95%CI: 1.2–12.1; p=0.02), respectively, when compared with normal D-dimer. The HR for recurrence associated with RVO was not significant, and RVO did not increase the recurrence risk associated with an abnormal D-dimer either at T0 or T1. In conclusion, an abnormal D-dimer during vitamin K antagonist (VKA) treatment or at one month after VKA withdrawal is a risk factor for recurrence in patients with provoked DVT, while RVO at the time of anticoagulation withdrawal is not.

Background: Venous thromboembolism (VTE) is a major complication of myeloma therapy recently observed with the increasing use of up-front thalidomide and dexamethasone (thal–dex). The pathogenesis of thal-induced VTE is not well recognized, and the role of prothrombotic factors, especially of thrombophilic abnormalities, is not yet determined. Material and methods: Two hundred and sixty-six patients with newly diagnosed multiple myeloma (MM) were primarily treated with thal–dex in preparation for subsequent high-dose therapy and autologous stem-cell transplantation. Out of these 266 patients, 190 were evaluated for thrombophilic alterations at baseline, and 125 of them were also re-assessed after thal–dex therapy. Results: The presence of genetic thrombophilic polymorphisms among patients with MM was superimposable to that of normal controls and was associated with a twofold increase in the relative risk of VTE. aAPCR and elevated factor VIII levels were frequent, albeit transient, alterations and were not associated with a significant increase in the risk of VTE. Two hundred and forty-six patients received a thromboprophylaxis with fixed low-dose warfarin (1.25 mg/day) during thal–dex therapy. Of these patients (or 10.6%), 26 had symptomatic VTE events. Their patients-years rate of VTE (35.5%) was significantly lower in comparison with the 86.2% rate recorded among the first 19 patients who initially entered the study and did not receive any kind of thromboprophylaxis (P = 0.043). Conclusions: On the basis of these data, a baseline thrombophilic work up is not recommended in patients with receiving up-front thal–dex. For these patients, fixed low-dose warfarin may be a valuable prophylaxis against VTE.

SummaryHeparin-induced thrombocytopenia (HIT) is a life-threatening complication of heparin treatment; the prognosis depends on early and accurate diagnosis, and prompt start of alternative anticoagulants. Because of high sensitivity, the commercially available immunologic assays are widely used, though not suited to be run on single samples and with a turnaround time of 2–3 hours. We evaluated two new, rapid, automated, semi-quantitative chemiluminescent immunoassays in HIT suspected patients: HemosIL® AcuStar HIT-IgG(PF4-H) (specific for IgG anti- PF4/heparin antibodies) and HemosIL® AcuStar HIT-Ab(PF4-H) (detecting IgG, IgM and IgA anti-PF4/heparin antibodies) (both from Instrumentation Laboratory). A total of 102 patients with suspected HIT were included; HIT was diagnosed in 17 (16.7%). No false negative cases were observed using either the HemosIL AcuStar HIT-IgG(PF4-H) or the HITAb(PF4-H) assay (sensitivity and negative predictive values = 100%; negative likelihood ratios

SummaryFew data are available on thrombophilic risk factors and progression of atherosclerotic peripheral arterial disease (PAD). Thrombophilic alterations can be an aggravating factor when arterial stenoses are present. In a cross-sectional study, we evaluated the presence of the thrombophilic factors fibrinogen, homocysteine, factor (F)VIII, lupus anticoagulant (LAC), FII G20210A, and FV R506Q mutations in 181 patients with PAD at Fontaine’s stage II (claudication), in 110 patients with critical limb ischaemia (CLI), and in 210 controls. Fibrinogen was higher in patients with CLI vs. those with claudication and controls (427.9 ± 10.5 vs. 373.1 ± 5.2 vs. 348.9 ± 7.0 p=0.001, respectively). Homocysteine and FVIII were higher in patients with PAD than in controls, but were similar in patients with CLI and claudication. The prevalence of LAC increased in patients with CLI vs. those with claudication and controls (21.4% vs. 7.8% vs. 5.2% p

Background The optimal dose of low-molecular-weight-heparin (LMWH) to prevent venous thromboembolism (VTE) after bariatric surgery remains controversial. Aim The aim of this study was to evaluate the pharmacodynamic parameters of two doses of the LMWH parnaparin administered to patients undergoing bariatric surgery. Methods Patients were enrolled in a multicentre, open label, pilot study and were randomised to receive 4250 IU/day [n = 36; 30 females; median age: 38 years (23-56); median BMI: 46.7 Kg/m2 (36.5-58.8)] or 6400 IU/day [n = 30; 24 females; median age: 42 years (22-63); median BMI: 43.7 Kg/m2 (36.1-64.1)] of parnaparin s.c. for 7-11 days. The pharmacodynamic effects of parnaparin were analysed by measuring the anti Factor Xa activity on day 0 (12 hours after the first parnaparin injection), day 4 and day 6 after surgery (before and 4 hours after parnaparin administration). Results In 98.3% of patients receiving 4250 IU/day the peak anti-Xa levels were in the range of 0.1-0.4 IU/ml. Higher anti-Xa levels were observed in patients receiving 6400 IU/day: in 62.3% of these patients the peak anti-Xa levels were greater than 0.4 IU/ml. The anti-Xa levels measured 4 hours after injection on days 4 and 6 were not statistically correlated with BMI for either dose of-parnaparin (p = 0.077 and p = 0.401 for 4250 or 6400 IU/day, respectively). Conclusion The dose of 4250 IU/day seems adequate to achieve prophylactic anti-Xa levels in morbid obese patients undergoing bariatric surgery. Conversely, most of the patients receiving 6.400 IU/day show anti-Xa levels higher than the recommended prophylactic values.

Background and objectives: To assess the predictive value of D-dimer (D-d) and Factor VIII (FVIII) in combination for recurrent venous thromboembolism (VTE) after vitamin K antagonist (VKA) therapy suspension. Design and methods: Consecutive outpatients with a first episode of idiopathic proximal deep vein thrombosis of the lower limbs were enrolled on the day of VKA suspension. After 30+/−10 days, D-d (cut-off value: 500 ng/mL), chromogenic FVIII activity and inherited thrombophilia were determined. Follow-up was 2 years. Results: Overall recurrence rate was 16.4% (55/336; 95% CI:13–21%). The multivariate hazard ratio (HR) for recurrence was 2.45 (95% CI: 1.24–4.99) for abnormal D-d and 2.76 (95% CI:1.57–4.85) for FVIII above the 75th percentile (2.42 U/mL) after adjustment for age, sex, thrombophilia, VKA duration and residual venous obstruction. When compared with normal D-d and FVIII, the multivariate HR was 4.5 (95% CI: 1.7–12.2) for normal D-d with FVIII above 2.42 U/mL and 2.7 (95% CI: 1.2–6.6) and 7.1 (95% CI:2.8–17.6) for abnormal D-d with FVIII, respectively, below and above 2.42 U/mL. Interpretation and conclusions: D-d and FVIII at 30+/−10 days after VKA withdrawal are independent risk factors for recurrent VTE.

Essentials Prothrombin and partial thromboplastin time (PT/PTT) measure direct oral anticoagulants (DOACs). PT, PTT and specific tests for DOACs were performed on patients treated for atrial fibrillation. Normal PT/PTT don't exclude DOAC activity and their prolongation doesn't confirm DOAC action. The use of PT or PTT to evaluate DOAC activity could cause dangerous misinterpretations. Summary: Background Prothrombin time (PT) and activated partial thromboplastin time (APTT) have been proposed to measure the effect of oral anti-activated factor X (FXa) or anti-activated FII drugs, respectively. Aims To evaluate the relationships and responsiveness of PT and APTT versus direct oral anticoagulant (DOAC) concentrations measured with specific coagulation tests performed with different platforms in four Italian anticoagulation clinics. Methods Six hundred and thirty-five patients with atrial fibrillation participated in the study: 240 were receiving dabigatran, 264 were receiving rivaroxaban, and 131 were receiving apixaban. Blood was taken at trough and peak within the first month (15–25 days) of treatment. PT, APTT, diluted thrombin time (dTT) calibrated for dabigatran and anti-FXa calibrated for rivaroxaban or apixaban were determined. Results For dabigatran, the correlation between APTT and dTT ranged from r = 0.80 to r = 0.62. For rivaroxaban, the correlation between the anti-FXa assay and PT ranged from r = 0.91 to r = 0.73. For apixaban, the correlation between the anti-FXa assay and PT was lower than for the two other drugs (r = 0.81 to r = 0.54). Despite the above significant correlations, the responsiveness of PT or APTT was relatively poor. A discrepancy between global testing and DOAC plasma concentrations was shown in a considerable proportion of patients, depending on the platform and drug, with values ranging from 6% to 62%. Conclusions Overall, poor responsiveness of the screening tests to DOAC concentrations was observed. PT and APTT normal values cannot exclude DOAC anticoagulant activity, and PT or APTT prolongation is not always associated with DOAC anticoagulant effect as determined with specific tests.

Background:Laboratory investigation with specific factor XIII (FXIII) assays plays a crucial role in diagnosis of FXIII deficiency. According to the International Society on Thrombosis and Hemostasis (ISTH), it is necessary a blank sample with iodoacetamide, provided by the kit or locally prepared, when the ammonia release assays are used, to avoid FXIII activity overestimation.Methods:In this study we set up a modification of the Berichrom FXIII chromogenic assay, in which iodoacetamide was added by the BCS analyzer in the reaction mixture of the blank sample, without modifications of the original reagents. We analyzed 100 plasma samples of outpatients with clinical symptoms suggestive of a bleeding diathesis (20 samples had FXIII activity Results:In all samples blank subtraction significantly reduced FXIII activity, mostly in the low activity range group (from 10.1% to 2.4%, pConclusions:Despite the low number of samples included in the study, the described automatic procedure seemed to decrease FXIII activity overestimation and, especially for low activity range samples (

SummaryWe assessed the predictive value of D-dimer levels in combination with residual venous obstruction (RVO) for recurrent venous thromboembolism (VTE) in a prospective cohort of outpatients after oral anticoagulant therapy (OAT) suspension for a first episode of idiopathic proximal deep vein thrombosis of the lower limbs during a 2-year follow-up. Patients (n=400) were enrolled on the day of OAT suspension when RVO was determined by compression ultrasonography (present in 48.6% of patients). D-dimer (cut-off value: 500 ng/mL) was measured 30±10 days afterwards (abnormal in 56.4% of patients). The overall recurrence rate was 16.7% (67/400; 95% confidence intervals - CI -:13–21%). The multivariate hazard ratio (HR) for recurrence was 3.32 (95% CI:1.78–6.75; p > 0.0001) for abnormal D-dimer compared to normal D-dimer and 1.2 (95% CI:0.72–2.07; p>0.05) for RVO compared to absent RVO. The recurrence rate was 5.7% (95% CI:2–13%) and 10.4% (95% CI:6–18%), respectively, for normal D-dimer either without or with RVO, 22.9% (95% CI:14–33%) and 25.9% (95% CI: 18–35%), respectively, for abnormal D-dimer, either without or with RVO. When compared with normal D-dimer without RVO, the multivariate HR for recurrence was similar for abnormal D-dimer either with RVO (4.76 – 95% CI:1.78–12.8) or without RVO (4.3–95%:1.56–11.88). Abnormal D-dimer at one month after OAT withdrawal is an independent risk factor for recurrent VTE, while RVO at the time of OAT withdrawal, either with normal or abnormal D-dimer after one month, does not influence the risk of recurrence.

The accuracy of a new bedside, rapid and quantitative D-Dimer assay (Cardiac D-Dimer) was evaluated in outpatients with clinically suspected deep vein thrombosis (DVT); VIDAS test was used as reference method. Eighty consecutive outpatients with suspected DVT of a lower limb were included in the study. Patients were classified as DVT positive or negative according to results of objective test (serial CUS), pretest clinical probability and 3-month follow-up. DVT was diagnosed in 32/80 patients (40%). The performance of the two D-Dimer assays was comparable, as indicated by the areas under the ROC curves (0.89 and 0.88, for Cardiac D-Dimer and VIDAS, respectively) and the coefficient of correlation (r=0.91). The reproducibility of the test was acceptable (from 6.2% to 12.0%). The sensitivity and negative predictive values were 100% for both tests. The specificity (SP) and positive predictive values (PPV) were similar (SP: 50.0% and 52.0%, PPV: 57.1% and 58.2%, for Cardiac D-Dimer and VIDAS, respectively). The Cardiac D-Dimer test proved to be very accurate and produced results fully comparable to those obtained with the VIDAS test. Since the test can be directly performed in the emergency room within a few minutes, it seems to have great clinical potential. The place of this assay in the diagnostic strategy of DVT remains to be determined in prospective management studies.

not available

Background: D-dimer role is well established in the diagnostic work-up for lower limb deep vein thrombosis (DVT), however it has not been formally tested for clinically suspected upper extremity DVT and/or superficial vein thrombosis (SVT). Aim: To ascertain D-dimer diagnostic accuracy for upper extremity DVT and/or SVT. Study design: We performed a single centre management study in outpatients referred by emergency or primary care physicians for clinically suspected upper extremity DVT. All patients underwent D-dimer testing (cut-off value: = 93\% for excluding DVT in symptomatic outpatients and it can be a useful test in the diagnostic work-up of suspected upper extremity DVT. (C) 2015 Elsevier Ltd. All rights reserved.

Summary Introduction The use of adapted cut-off values in the elderly, combined with clinical probability (PTP), increases the proportion of patients in whom venous thromboembolism (VTE) can be safely excluded, compared with the conventional cut-off value of 500 μg/L fibrinogen equivalent units (FEU). We evaluated the clinical performance of three different approaches to establish cut-off values for a D-dimer assay whose results are expressed in D-dimer units (D-DU). Methods HemosIL D-dimer HS assay (Instrumentation Laboratory) was performed in 279 consecutive outpatients with suspected deep venous thrombosis (DVT) and nonhigh PTP. Results Considering patients >60 years, the number of negative D-dimer results increased using the modified (376 ng/mL if ≥60 years) and the age-adjusted cut-off (age years × 5 ng/mL if >50 years) compared to the conventional one (230 ng/mL for all patients; 54.6%, 58.2%, and 25.0%, respectively), with no false-negative results. The higher increase was observed in patients >80 years (43.9%, 56.1%, and 8.8%, respectively). Conclusion For the HemosIL D-dimer HS, the use of specific cut-off values in older subjects with suspected DVT and nonhigh PTP increases the number of patients in whom DVT can be safely excluded.

Background Post-thrombotic syndrome (PTS) is the most common complication of deep vein thrombosis (DVT), but few data are available on the risk factors for PTS. Aims To assess whether the time-course of D-dimer, FVIII, and thrombotic burden are related to PTS development. Methods Patients (n = 59) with proximal DVT of the lower limbs (age 64; range:20-88 years; male 56%) were enrolled on the day of diagnosis (D0) and all received heparin for 5-7 days, overlapped and followed by vitamin K antagonists (VKA) for 3 months. Whole-leg compression ultrasound examination was conducted on D0 and 7 (D7), 30 (D30), and 90 (D90) days afterwards, when blood samples were also taken for D-dimer (STA Liatest) and FVIII (chromogenic assay) testing. Thrombotic burden was defined at each time point according to a score, which considered thrombosis extent and occlusion degree. Villalta score was evaluated at D30, D90, and D180. Results At D90, 12 patients developed PTS (Villalta score ≥ 5) and the median Villalta score was 1 (IQR 0.3-3.0) and was not correlated with either D-dimer or FVIIII time course. At D180, 13 patients had PTS and they had similar thrombotic score at D0, D30 to those without PTS, but higher at D90 (7.6 ± 5.1 vs. 3.2 ± 3.6; p = 0.011). Thrombotic score at D90 was correlated with Villalta score at D90 (rho = 0.374, p = 0.009) and at D180 (rho = 0.436, p = 0.006). Conclusions Thrombotic burden after 90 days of VKA is correlated with PTS.

Inherited and acquired thrombophilic alterations in patients with superficial vein thrombosis of lower limbs

In family studies, the risk for venous thromboembolism (VTE) in relatives with factor V Leiden (FVL) or G20210A prothrombin (PT20210A) gene polymorphisms may differ according to genotype and clinical presentation of the proband. To address this hypothesis, a retrospective cohort family study was carried out on 192 kindreds with at least one member with homozygous FVL or PT20210A, for a total of 886 relatives. The proband of the family was heterozygous in 68 and homozygous or with both polymorphisms in 124 kindreds. Twenty-three probands were asymptomatic, 11 had had arterial thrombosis, 7 obstetrical complications, and 151 venous thrombosis (122 VTE and 29 superficial vein thrombosis). The incidence of VTE (per 1000 patient-years) in relatives was higher when the proband had heterozygous rather than homozygous polymorphism (1.25 [95\% confidence interval (CI), 0.73-1.91] vs 0.44 [0.19-0.78]) and when the proband had had VTE instead of other or no clinical manifestations (0.95 [0.57-1.42] vs 0.50 [0.19-0.96]). Compared with relatives belonging to kindreds with homozygous probands without VTE, the adjusted hazard ratio of VTE for relatives selected from kindreds with heterozygous probands with VTE was 4.14 (95\% CI, 1.17-14.71). The genotype and clinical presentation of the proband influence the risk for VTE in relatives with FVL or PT20210A.

Dear Sirs, Skov et al. object that the effect of the variant allele rs7294 which is associated with higher warfarin requirements is not relevant in our dosing algorithm, its effect being significant at the univariate but not at the multivariate analysis. Skov et al. also show that there is not a complete linkage disequilibrium but a significant correlation between rs 7294 and the variant allele rs 9934438 which is associated with warfarin sensitivity, based on the data of their study [1]. The frequency of the variant allele rs 7294 was 9.6% in their study vs 7.3% in our derivation group and 10% in the validation group. The partial linkage disequilibrium between the rs 7294 and the rs 9934438 is also consistent with data previously published by Wadelius et al [2]. In the algorithm recently elaborated by Pavani et al. [3], various parameters were included in the multiple linear regression model, and they concluded that the incorporation of VKORC1*3 (rs 7294) and VKORC1*4 (6009 C/T) could help in a precise prediction of therapeutic warfarin dose. Moreover, in a recent meta-analysis [4], Jorgensen et al. showed that for the Caucasian ethnic group, the pooled effect estimate of the VKORC SNP rs 7294 on warfarin dosing was nonsignificant for heterozygotes versus wild-types, but was statistically significant for mutant-types versus wild-types. In our study [5], we chose to employ a simultaneous multivariate regression as our analysis was exploratory and hypothesis generating. The loss of significance of the effect of rs 7294 at the multivariate analysis could be due to our limited sample size, as acknowledged in our discussion, and larger studies are required to confirm our algorithm.

Background: Pretest clinical probability with the Wells rule and D-dimer have been widely investigated for the diagnosis of symptomatic proximal deep vein thrombosis (DVT) of the lower limbs, but they have not been formally tested for symptomatic isolated distal DVT diagnosis. Objective: To evaluate the diagnostic accuracy of the Wells rule and D-dimer for isolated distal DVT. Design, Setting, and Patients: This was a single-center, cross-sectional study including 873 consecutive outpatients with suspected DVT, in whom pretest clinical probability determination, D-dimer determination (STA Liatest; cut-off of 95% for isolated distal DVT. not available

Warfarin dosing is affected by clinical and genetic variants, but the contribution of the genotype associated with warfarin resistance in pharmacogenetic algorithms has not been well assessed yet. We developed a new dosing algorithm including polymorphisms associated both with warfarin sensitivity and resistance in the Italian population, and its performance was compared with those of eight previously published algorithms.Clinical and genetic data (CYP2C9*2, CYP2C9*3, VKORC1 -1639 GA, and VKORC1 3730 GA) were used to elaborate the new algorithm. Derivation and validation groups comprised 55 (58.2% men, mean age 69 years) and 40 (57.5% men, mean age 70 years) patients, respectively, who were on stable anticoagulation therapy for at least 3 months with different oral anticoagulation therapy (OAT) indications.Performance of the new algorithm, evaluated with mean absolute error (MAE) defined as the absolute value of the difference between observed daily maintenance dose and predicted daily dose, correlation with the observed dose and R(2) value, was comparable with or slightly lower than that obtained using the other algorithms. The new algorithm could correctly assign 53.3%, 50.0%, and 57.1% of patients to the low (≤25 mg/week), intermediate (26-44 mg/week) and high (≥ 45 mg/week) dosing range, respectively. Our data showed a significant increase in predictive accuracy among patients requiring high warfarin dose compared with the other algorithms (ranging from 0% to 28.6%).The algorithm including VKORC1 3730 GA, associated with warfarin resistance, allowed a more accurate identification of resistant patients who require higher warfarin dosage.

The Prolong study shows that continuing vitamin K antagonists (VKA) in patients with abnormal D: -dimer (evaluated by a qualitative assay, Clearview Simplify D: -dimer) results in a significant reduction of venous thromboembolism (VTE) recurrence. The present study retrospectively analyzes a subgroup of patients enrolled in the Prolong study with a view to calculate cut-off values for six quantitative D: -dimer methods to predict the risk of VTE recurrence. We measured D: -dimer levels by VIDAS D: -dimer Exclusion (bioMerieux), STA Liatest D: -dimer (DiagnosticaStago), HemosIL D: -dimer and HemosIL D: -dimer HS (Instrumentation Laboratory), Innovance D: -dimer (Siemens) and AutoDimer (Trinity Biotech) in frozen plasma aliquots sampled 30 ± 10 days after VKA cessation in 390 patients enrolled in the Prolong study. During follow-up (562.7 years), 28 patients had recurrent VTE (7.2%, 5.0% person-years). Since D: -dimer levels are positively correlated with age and significantly lower in men, we calculated method-specific cut-off values according to age and gender. The HRs for VTE recurrence calculated using method-specific cut-off values based on age and gender are higher than those using cut-off values indicated by the manufacturers for VTE exclusion in symptomatic outpatients. These data suggest that method-specific cut-off values calculated according to patient age and gender can be more accurate in identifying patients at a higher risk for VTE recurrence. These method-specific cut-off values are being evaluated in the ongoing prospective management multicenter DULCIS study.

Background Congenital thrombophilia is a risk factor for venous thromboembolism (VTE). Whether it is associated with increased risk of arterial disease is today a matter of debate. We aimed to look for early signs of atherosclerotic alterations in carriers of inherited thrombophilic alterations (ITA). Methods Between January 2006 and September 2008 ultrasonography assessment of the carotid arteries with measurement of intima-media thickness (IMT), and determination of the ankle/brachial pressure index (ABI), was performed in: a) 161 carriers of ITA (deficiency of antithrombin, protein C or S, factor V Leiden or prothrombin G20210A mutations), 84 of whom with previous VTE, and b) 180 subjects without ITA, matched for age, sex and previous VTE. All subjects were Results Carotid plaques were found in 8 subjects [3 (1.9%) with ITA]. Increased IMT values (> 1 mm) were detected in 6 subjects with and 1 without thrombophilia (p = 0.055). The prevalence of IMT values > 90th percentile was not different in subjects with/without thrombophilia (15.2% vs 11.6%, p = 0.416). At multivariate analysis only age was significantly associated with increased odds ratios for IMT values > 90th percentile. No subjects had abnormal ( Conclusions The present study, the first to investigate the presence of atherosclerotic markers in relatively young subjects with inherited thrombophilia, did not find a particular prevalence of signs of early atherosclerotic markers in these subjects.

Introduction D-dimer testing is widely used in conjunction with clinical pretest probability (PTP) for venous thromboembolism (VTE) exclusion. We report on a multicenter evaluation of a new, automated, latex enhanced turbidimetric immunoassay [HemosIL® D-Dimer HS 500, Instrumentation Laboratory (IL)]. Materials and Methods 747 consecutive outpatients with suspected proximal deep vein thrombosis (DVT, n = 401) or pulmonary embolism (PE, n = 346) were evaluated at four university hospitals in a management study with a 3 month follow-up. Samples were tested at each center using the new D-dimer assay on an automated coagulation analyzer [ACL TOP (IL)], with clinical cut-off for VTE at 500 ng/mL (FEU). Results The sensitivity and negative predictive value (NPV) were 100% for all PTP subgroups (no false negative results); for both sensitivity and NPV the lower limit of the 95% CI in patients with moderate/low PTP was higher than 95%. The overall specificity was 45.1% (95%CI: 41.1-49.3%). Higher specificity value was recorded in the low PTP subgroup [49.2% (95%CI: 41.7-56.7)]. No significant differences were found between patients suspected of having DVT or PE; sensitivity and NPV were 100%. The reproducibility of the assay was good, being the total CVs% less than 10% for D-dimer concentration near the clinical cut-off. Conclusions The new, highly sensitive D-dimer assay proved to be accurate when used for VTE diagnostic work-up in outpatients. Based on 100% sensitivity and NPV and lower limit of the 95% CI higher than 95%, the assay can be used as a stand-alone test in patients with non high PTP.

This study prospectively evaluated the relationship between activated partial thromboplastin time (aPTT) and risk of venous thromboembolism (VTE) recurrence after oral anticoagulant (OA) withdrawal in patients with a previous unprovoked VTE event. Six hundred twenty-eight patients (331 males; median age: 67 years) were followed after OA interruption (mean follow-up = 22 months). Three to four weeks from OA discontinuation patients were given a complete thrombophilic work-out, including aPTT (automated aPTT). Recurrent symptomatic VTE events (objectively documented) occurred in 71/628 (11.3%, 6.8/100 person-years) patients. The VTE recurrence rate was 17.5% and 7.5% in patients with aPTT in the lower (ratio < or =0.90) and in the upper (ratio >1.05) quartiles. The recurrence risk was more than twofold higher in patients with ratio < or =0.90 versus those of the reference category [Relative risk (RR): 2.38 (95% confidence interval (CI): 1.18-4.78)]. As expected, the increase in recurrence risk disappeared after adjustment for factor VIII, IX and XI levels [RR: 1.74 (95%CI: 0.43-2.76)]. In contrast, the risk was persistently increased in patients with a ratio < or =0.90 [RR: 2.07 (95%CI: 1.02-4.18)] after adjustment for age, gender and d-dimer level. The aPTT predictive value was independent of the presence of inherited thrombophilic alterations. In conclusion, abnormally short aPTT values are associated with a significantly increased risk of VTE recurrence.

Summary. Background and Aim: Several factors are associated with an increased risk of recurrent venous thromboembolism (VTE). The aim of the study was to investigate whether the quality of oral anticoagulation therapy (OAT) is a long-term risk factor for recurrence of VTE after OAT interruption. Methods and results: A total of 297 patients (170 males) with a recent acute unprovoked VTE episode were prospectively monitored during OAT in our anticoagulation clinic and followed up for 21 months after OAT interruption. Recurrent events were recorded in 42 subjects for 493 years of follow-up [14.1% of patients; 8.5% patient-years (pt-y)] after OAT withdrawal. The rate of recurrence was not correlated to OAT duration. Subjects experiencing recurrence after OAT interruption had spent significantly more time at markedly subtherapeutic international normalized ratio (INR) levels (

High levels of factor VIII are a common risk factor for venous thromboembolism (VTE). The aim of this study was to evaluate the possible interaction between the presence of high factor VIII levels and oral contraceptive (OC) use.Factor VIII levels were measured by a chromogenic assay in 174 women who suffered from VTE in reproductive age and in 484 healthy women. Subjects carrying thrombophilic alterations were excluded.Factor VIII levels were stratified into quartiles. The adjusted odds ratio (OR) of VTE in subjects with factor VIII levels in the upper quartile (1.95 IU/mL) was 7.45 (95%CI: 3.80-14.6). Among the 174 patients, 85 had experienced VTE during OC use. The 179 healthy women who had used OC for at least 6 months in the two years before presentation but had stopped OC at least 3 months before the blood sampling were considered as OC users. The risk of VTE among OC users with factor VIII levels in the upper quartile was increased about 13-fold (OR: 13.0, 95% CI: 4.92-34.3).Our results showed that there is an increased risk of VTE due to oral contraceptive use in women with elevated factor VIII and, as has been previously described for factor V Leiden and G20210A prothrombin mutations, the raised level of the coagulation factor and oral contraceptive use seem to have a synergistic effect.

SummaryThe factor V Leiden mutation (FVL), associated with reduced sensitivity to activated Protein C (APC), is a risk factor for venous thromboembolism (VTE) and displays a strong interaction with oral contraceptives (OC). The aim of this study was to evaluate the risk of VTE in OC users with reduced APC sensitivity unrelated to the FVL. APC sensitivity was measured by an original aPTT-based test (without sample pre-dilution in factor V-deficient plasma) in 195 women who suffered from VTE in reproductive age and in 487 healthy women with results being expressed as normalized ratio. Subjects with currently known clinically relevant thrombophilic alterations were excluded. APC normalized ratios were stratified into quartiles. The adjusted ORs of subjects in the lower quartile (≤0.90) was 2.46 (95%CI: 1.02–5.95). Of the 195 patients, 89 had suffered VTE during OC. The 181 healthy women who had used OC for at least 6 months in the two year period before presentation but who had stopped OC at least 3 months before blood sampling were considered OC users. The risk of VTE in subjects using OC with APC normalized ratio in the lower quartile was increased 4.9-fold (95% CI: 1.92–12.6). In conclusion, our results showed that altered APC resistance in women not carrying the FVL significantly increased the VTE risk, albeit to a lesser extent than in women also carrying the FVL. Our data also showed that OC use in women with altered APC resistance further increased the risk of VTE in a way that exceeded the additive expectation.

Introduction: The aim of the study was to evaluate the mechanism of the anticoagulant action of sulodexide, a mixture of glycosaminoglycans (GAGs) composed of dermatan sulfate (DS) and fast moving heparin (FMH), in vitro. Materials and methods: Thrombin clotting time (TCT) was measured in human platelet poor plasma (PPP). A chromogenic substrate assay was used to determine the pseudo-first order constant kinetic of thrombin inhibition (k′=kobs/min) either in defibrinated PPP or antithrombin (AT) or heparin cofactor II (HCII) depleted defibrinated PPP in the absence and presence of sulodexide or its components, alone and in combination. The interaction between DS and FMH was analysed by both the algebraic fractional and isobole graphical methods. Results: Sulodexide, DS and FMH produced a dose-dependent prolongation of TCT with unclottable TCT at sulodexide above 4 μg/ml and at DS or FMH above 5 μg/ml. Sulodexide and its components alone and in combination produced a dose-dependent linear increase in the rate of thrombin inhibition in defibrinated PPP. The algebraic fractional and the isobole graphical methods indicated an additive effect between DS and FMH. In AT depleted PPP, the dose-dependent increase in k′ produced by sulodexide was significantly lower than in PPP, while the dose-dependent increase in k′ produced by DS was similar to the increase produced in PPP. In HCII depleted PPP, the dose-dependent increase in k′ produced by sulodexide was significantly lower than in PPP, while the dose-dependent increase in k′ produced by FMH was similar to the increase produced in PPP. Conclusions: Thrombin inhibition produced by sulodexide is due to the additive effect of its components, namely, HCII catalysis by DS and AT catalysis by FMH. © 2003 Elsevier Science Ltd. All rights reserved.

Influence of low-density lipoprotein (LDL) receptor-related protein and ABO blood group genotypes on factor XI levels

Thalidomide has emerged as an active agent for the management of advanced multiple myeloma (MM) and is currently under investigation also in patients with newly diagnosed disease.[1][1] It is relatively well tolerated; more common side effects include constipation, sedation, skin rash, fatigue, and