Effect of hemostatic risk factors on the individual probability of thrombosis during pregnancy and the puerperium

In a retrospective study of 190 women with a first history of venous thromboembolism during pregnancy and the puerperium and 190 age-matched women with at least one prior pregnancy and no history of venous thromboembolism, the individual probability of thrombosis was determined. Assuming an overall risk of 1 in 1500 pregnancies, the probability of pregnancy-related thrombosis in carriers of homozygous factor V Leiden was 1 in 80 (odds ratio 20.6, p=0.005) and among carriers of combined heterozygous factor V Leiden and heterozygous G20210A mutation in the prothrombin gene 1 in 20 (odds ratio 88, p<0.001). The probability of thrombosis per pregnancy among women with elevated levels of factor VIII:C (>172 % activity) was 1 in 385 (odds ratio 4.5, p<0.001) and among those with increased levels of von Willebrand factor antigen (>190 %) 1 in 435 (odds ratio 4.0, p=0.002), independent of elevated factor VIII:C levels. The high prevalence of combined and homozygous defects of hemostatic components (21.6%) in patients as compared with normal women (0.86%) supports the concept that venous thromboembolism is a multicausal disorder.     

The prevalence of C677T mutation in the methylenetetrahydrofolate reductase gene and its association with venous thrombophilia in Taiwanese Chinese

C677T mutation of the methylenetetrahydrofolate reductase gene remains a controversial risk factor for venous thrombosis in Whites. The prevalence of methylenetetrahydrofolate reductase C677T genotype and its association with vascular thrombosis are not well established in Chinese population. We conducted a case-control study to investigate the prevalence of methylenetetrahydrofolate reductase C677T gene mutation and its association with venous thrombophilia in Taiwanese Chinese. The subjects consisted of 112 venous thrombophilic patients and 125 healthy controls, with similar age (p=0.08) and sex (p=0.58). The prevalent rates of C/T heterozygote were 32.8 and 44.6%; whereas those of T/T homozygote were 6.4 and 8.0% in the controls and patients, respectively. Neither C/T heterozygote (odds ratio, 1.7; 95% confidence interval, 1.0-3.0, p=0.05] nor T/T homozygote (odds ratio, 1.4; 95% confidence interval, 0.5-4.0, p=0.5) was significantly associated with venous thrombosis. Even when only subjects (52 patients and 107 controls) with normal inhibitor protein levels were analyzed, the association of T/T homozygote with venous thrombosis remained insignificant (p=0.06) with an odds ratio (95% confidence interval) of 3.4 (0.99-11.7). We concluded that, in Taiwanese Chinese, methylenetetrahydrofolate reductase C677T mutation is a common genetic mutation, but T/T homozygote is not a significant risk factor for venous thrombophilia.     

Efficacy and safety of enoxaparin in unselected patients with ST-segment elevation myocardial infarction

In randomized clinical trials the low-molecular-weight heparin enoxaparin has been shown to reduce ischemic complications in patients with acute ST elevation myocardial infarction (STEMI) treated with fibrinolysis. Little is known about the use and efficacy of enoxaparin in unselected patients with STEMI in clinical practice. In a retrospective analysis of the prospective ACOS registry we compared the outcomes of patients with STEMI treated with enoxaparin or unfractionated heparin. A total of 6,299 patients with STEMI < 12 hours were included in this analysis, 609 (10%) were treated with enoxaparin and 5,690 (90%) with unfractionated heparin. In the multivariable propensity score analysis enoxaparin was associated with a reduction in the combined endpoint of death and non-fatal reinfarction in the entire group (odds ratio 0.59; 95% CI 0.43-0.80) and the subgroups of patients treated without early reperfusion (odds ratio 0.65, 95% CI 0.43-0.97), fibrinolysis (odds ratio 0.64; 95% CI 0.33-1.26) and primary percutaneous coronary intervention (odds ratio 0.33; 95% CI 0.15-0.72). There was no significant increase in severe bleeding complications with enoxaparin (6.5% versus 5.5%, p = 0.4). In clinical practice in unselected patients with STEMI treated with or without early reperfusion therapy early treatment with enoxaparin compared to unfractionated heparin is associated with a significant reduction of the combined endpoint of inhospital death and reinfarction without a significant increase in severe bleeding complications.     

Oral anticoagulants as secondary prophylaxis of thrombosis in patients with polycythemia vera: a retrospective analysis of 15 patients

Thrombotic complications are the leading cause of mortality in patients with polycythemia vera (PV). Phlebotomy and myelosuppressive agents are able to reduce the frequency of thrombosis; however, despite adequate control of myeloproliferation, the thrombotic risk remains increased in PV. This has led to a search for additional antithrombotic agents suited to reduce the rate of thrombotic events in PV. We have retrospectively analyzed 15 patients with PV who received oral anticoagulants (OA) as secondary prophylaxis of thrombosis at our institution with the aim of investigating this treatment approach in patients with PV. Despite OA treatment, 2 (13%) of 15 patients displayed recurrent venous thromboembolism, 3 patients (20%) displayed recurrent arterial thromboembolism, whereas 1 patient (7%) developed recurrent restenosis/occlusion of a transjugular intrahepatic porto-systemic shunt (TIPSS) implanted because of an underlying Budd-Chiari syndrome. Three (20%) of 15 patients had a total of 5 bleeding events during OA treatment, two of which were major bleedings. In none of the major bleedings over-anticoagulation was the reason for bleeding. Within the limitations of a retrospective analysis in a small number of patients, our data suggest that meticulous control of anticoagulant therapy is of critical importance in patients with PV, since in several of our patients recurrent thromboembolic events were associated with a low anticoagulation intensity of INR<2.0. In our opinion, a prospective clinical trial similar to the recently performed ECLAP study would be needed to more thoroughly elucidate the efficacy of OA in the secondary prophylaxis of thrombosis in PV.     

Postmenopausal hormone replacement and venous thromboembolism following hip and knee arthroplasty

Hormone replacement therapy has been associated with venous thromboembolism. Controversy exists regarding the appropriate management of hormone replacement in the perioperative setting and in other situations--such as acute illness--predisposing to acute venous thromboembolism. We performed a case-control study to determine whether perioperative hormone replacement is associated with venous thromboembolism following hip and knee arthroplasty. 108 patients with postoperative venous thrombosis were matched by age, date and type of surgery, and surgeon with 210 controls without thrombosis. Perioperative hormone replacement use was no more prevalent in patients with postoperative thrombosis than those without. Eighteen (16.7%) women with post-operative thrombosis had taken perioperative hormone replacement compared to 49 (23.3%) of controls: odds ratio = 0.66; (95% CI 0.35-1.18; p=0.17). After multivariate analysis, the adjusted odds ratios were similar. Variables predicting post-operative thrombosis included: prior venous thromboembolism (OR = 2.3; p = 0.02), rheumatologic disease (OR = 2.2; p = 0.03), and absence of pharmacologic antithrombotic prophylaxis (OR = 13.4; p = 0.005). Cases and controls were otherwise similar. Users of hormone replacement were similar to non-users except that they were less likely to have coronary disease (OR 0.34; p = 0.03) or prior thrombosis (OR = 0.28; p = 0.04), and were younger (median age 67 versus 74 years; p <0.0001). We found no association between perioperative hormone replacement and post-operative thrombosis in patients undergoing major orthopaedic surgery. Routine discontinuation of these medications preoperatively--and possibly in other situations predisposing to thrombosis, such as acute medical illness--may be unnecessary in patients receiving appropriate pharmacologic antithrombotic prophylaxis.     

Antiphosphatidylethanolamine antibodies are associated with an increased odds ratio for thrombosis. A multicenter study with the participation of the European Forum on antiphospholipid antibodies

A multicenter study was set up to evaluate the prevalence, clinical and biological significance of antiphosphatidylethanolamine antibodies (aPE) in thrombotic patients with or without the main known clinical and biological risk factors for thrombosis. APE and antibodies, defined as the laboratory criteria of antiphospholipid syndrome (APS) -lupus anticoagulant, anticardiolipin and anti-beta(2)-GPI antibodies were measured in 270 patients with thrombosis (234 venous and 37 arterial) and 236 matched controls. APE were found in 15% of thrombotic patients compared to 3% of controls (p < 0.001) with no predominant isotype, no association with the main known clinical or biological risk factors for thrombosis neither with a type of thrombosis, arterial or venous. In a multivariate logistic regression analysis of antibodies, aPE showed the highest association with thrombosis (odds ratio [OR]: 4.2, p < 0.001). Moreover, using a multivariate analysis in a case-control subgroup study on 158 patients, IgGaPE were found to be significantly associated with venous thrombosis (OR:6;p = 0.005). Interestingly, 25 of the 40 aPE-positive patients (63%) were negative for the APS laboratory criteria. Most of them (21/25) had venous thrombosis, recurrent in ten of them. Four patients also suffered from early or late miscarriages. Our results underline the strength of the association between the presence of aPE and thrombosis and suggest their measurement in thrombotic patients, especially when lupus anticoagulant, anticardiolipin or anti-beta(2)-GPI antibodies are absent.     

Lupus anticoagulants and thrombosis: clinical association of different coagulation and immunologic tests

The dilute Russell's viper venom time (dRVVT) and the kaolin clotting time (KCT) are two among the most commonly used coagulation tests for the detection of lupus anticoagulants. The dRVVT seems superior to the KCT in identifying LA-positive patients at risk of thrombosis. However, this relationship is greatly influenced by both the source of reagents and the instrumentation employed to carry out the assays. Therefore, 4 dRVVTs ("home-made" dRVVT, DVV test, Bioclot LA, LA Screen), and one KCT (Kaoclot) were performed in two centers and compared for their retrospective correlation with the thrombotic complications of 72 patients with a previously established diagnosis of lupus anticoagulants. Two other assays ("home-made" KCT, and Colloidal Silica Clotting Time, CSCT) were performed in one of the two centers, and compared with Kaoclot for their clinical correlations in the same population of patients, 44 of whom (61%) had suffered from arterial and/or venous thrombosis. A rather good degree of inter-laboratory and inter-assay correlations of the different tests was found. However, a statistically significant association with thrombosis was found only with the coagulation profile generated using the "home-made" dRVVT. When the commercially available dRVVTs were used, none of the coagulation profiles remained associated with thrombosis. When the assays were analyzed separately, the association with thrombosis was statistically significant for LA screen (p = 0.0019), DVV test (p = 0.0043), and Bioclot (p = 0.0255), and of borderline significance for the "home-made" dRVVT (p = 0.0503) in one center. This last assay was also significantly associated with thrombosis in the other center (p = 0.0139). When venous and arterial thrombosis were considered separately, DVV test was statistically associated with venous thrombosis in both centers (p = 0.0076 and p = 0.0187, respectively), and LA screen in one center (p = 0.0303). No dRVVT was found to correlate with arterial thrombosis. Kaoclot, Colloidal Silica Clotting Time, and the "home-made" KCT did not correlate with thrombosis. The prevalence of IgG and/or IgM antibodies to cardiolipin, beta2-glycoprotein I and prothrombin were 74%, 86% and 85%, respectively. Increased titers of IgG anticardiolipin antibodies were associated with arterial thrombosis (p = 0.0375), whereas IgM anti-beta2-glycoprotein I antibodies were associated with venous thrombosis (p = 0.0433). In conclusion, these retrospective data support the notion that the dRVVT, rather than other coagulation or ELISA tests, are able to identify lupus anticoagulant-positive patients at risk of thrombosis. This property appears common to several commercially available dRVVT kits, making this type of assay the ideal target of future efforts of laboratory standardization.     

Heparin assays and bleeding complications in treatment of deep venous thrombosis with particular reference to retroperitoneal bleeding

Bleeding complications occurred in 30 (11%) out of 280 patients who received continuous heparin infusion for deep venous thrombosis (DVT). 22 (8%) had minor while 8 patients (3%) had major bleeding complications (1 intrathoracic [fatal], 2 gastrointestinal and 5 retroperitoneal). Heparin activity, in daily drawn blood samples, was determined by four assays (chromogenic substrate [CS] assay, activated partial thromboplastin time [APTT], thrombin time with citrated plasma [CiTT] and thrombin time with recalcified plasma [CaTT]). The differences in median heparin activity between patients with minor bleeding and patients with no bleeding did not reach significance for any of the tests. In patients with major bleeding, the differences were significant with the CS (p = .011) and the CaTT (p = .030) assays. Patients with retroperitoneal bleeding had significantly increased median activity judged by all four assays: CS (p = .002), CaTT (p = .003), APTT (p = .010), CiTT (p = .029). The difference was most pronounced after four days of heparin treatment, but there was a considerable overlap with patients without bleeding.     

Recurrent venous thrombosis and markers of inflammation

Inflammatory processes may play a key role in venous thrombosis, by inducing a procoagulant state through the action of cytokines and chemokines on monocytes and endothelial cells. Plasma concentrations of three inflammatory mediators, interleukin 6 (IL-6), interleukin 8 (IL-8) and monocyte chemotactic protein 1 (MCP-1), that mediate the cross-talk between inflammation and coagulation, were measured in 182 subjects with recurrent venous thrombosis and 350 healthy subjects recruited through a general practice. Elevated levels of IL-6 (>90th percentile of the control group) were detected in 25.8% of the patients with venous thrombosis in comparison with 10% (by definition) of the controls [odds ratio 2.4 (95%CI 1.5-3.8)]. In 21.5% of the patients elevated plasma levels of IL-8 (>90th percentile) were determined [odds ratio 2.0 (95%CI 1.2-3.5)]. Elevated levels of MCP-1 (>90th percentile) were detected in 24.1% of the patients [odds ratio 1.9 (95%CI 1.2-3.2)]. This is the first large clinical study showing that an increase in inflammatory mediators is associated with venous thrombosis. Future prospective studies are necessary to clarify the causal nature of the inflammatory process with respect to venous thrombosis.     

Venous thrombosis in patients with solid tumors: determination of frequency and characteristics

Deep venous thrombosis (DVT) and pulmonary embolism (PE) are well recognized complications of cancer. However, our current knowledge of this association is derived from studies conducted more than a decade ago. In light of the changes in medical practice and the improvement in cancer care in recent years, a re-evaluation of the relationship between malignancy and venous thrombosis is in order. Of a total of 1041 patients with solid tumors admitted to 3 major medical centers, there were 81 (7.8%) diagnosed with DVT/PE. Patients were more likely to develop DVT/PE during chemotherapy (p = .0001). Advanced malignancies (p = .001), renal carcinoma (p = .005), pancreatic (p = .001), gastric (p = .014) and brain tumors (p = .001) were independent variables strongly associated with the occurrence of venous thrombosis. The occurrence of thrombotic events in the population tested in this study did not adversely affect survival (p = .082). The study identifies subset of patients with cancer at high risk for venous thrombosis. Early prophylaxis with anticoagulants in these patients may be warranted. Most importantly, further clinical trials are desperately awaited to detect possible new trends in the frequency and types of thrombotic events and to better define prevention strategies in cancer patients at risk for thrombosis. The association between venous thromboembolic disease (VTD) and malignant neoplastic disorders is well known and has been the subject of several reports for more than a century. There is a general agreement among investigators that thrombotic complications in patients with cancer occur at a rather high frequency, and that other circumstantial factors such as surgery or chemotherapy potentiates this risk. However, several important considerations pertaining to cancer and thrombosis continue to be shrouded in controversy. For example, there are inexplicable differences in the proportion of patients with cancer diagnosed with deep venous thrombosis (DVT) or pulmonary embolism (PE) reported in the literature. In the absence of large well-controlled studies, one may only postulate on the reasons that contributed to these differences. The inclusion of different types of VTD such as superficial, venous, arterial or vascular access device-induced thrombosis may have led to overestimation of the incidence of these events in patients with underlying malignancy. Another possible explanation for this discrepancy relates to the use of a variety of diagnostic and methodological criteria ranging from observation and clinical suspicion to more invasive procedures resulting in considerable differences in the rate of reported clotting events. Along the same line of discussion, one may argue whether VTD is a random event or constitutes a complication that occurs more commonly in patients with distinct characteristics and certain tumor types. To further investigate the association between malignancy and thrombosis, we evaluated 1041 patients with solid tumors for the risk of DVT/PE. The main objectives of the study were to determine the frequency of DVT/PE based on validated diagnostic criteria and to identify patients with cancer at high risk for developing these thrombotic episodes. Also, we evaluated the impact of VTD on the survival of these patients.     

Catechol-O-methyltransferase genotype is associated with plasma total homocysteine levels and may increase venous thrombosis risk

A disturbed methylation has been proposed as a mechanism via which homocysteine is associated with diseases like vascular disease, neural tube defects and mental disorders. Catechol-O-methyltransferase (COMT) is involved in the S-adenosylmethionine-dependent methylation of catecholamines and catecholestrogens and in this way contributes to homocysteine synthesis. COMT dysfunction has been related to schizophrenia and breast cancer. We hypothesized that COMT dysfunction by virtue of functional genetic polymorphisms may affect plasma total homocysteine (tHcy). Our primary objective was to study the association between common COMT polymorphisms and tHcy. Secondly, we evaluated these polymorphisms as a risk factor for recurrent venous thrombosis. We obtained genotype data from four polymorphisms in the COMT gene (rs2097603, rs4633, rs4680 [324G>A] and rs174699) from 401 population-based controls. We performed haplotype analysis to investigate the association between common haplotypes and tHcy. In addition, we assessed the rs4680 variant as a genetic risk factor in a case-control study on recurrent venous thrombosis (n = 169). We identified a common haplotype that was significantly associated with tHcy levels. This effect was largely explained by the rs4680 variant, resulting in an increase in tHcy of 10.4% (95% CI 0.01 to 0.21, p = 0.03) for 324AA compared with 324GG subjects. Interestingly, we found that the 324AA genotype was more common in venous thrombosis patients (OR 1.61 [95% CI 0.97 to 2.65], p = 0.06) compared to control subjects. We show that the COMT rs4680 variant modulates tHcy, and might be associated with venous thrombosis risk as well.     

Low molecular weight heparin (enoxaparin) versus oral anticoagulant therapy (acenocoumarol) in the long-term treatment of deep venous thrombosis in the elderly: a randomized trial

This study aims to establish the relative effectiveness and safety of low molecular weight heparin in elderly patients with venous thrombosis in order to find an alternative to oral anticoagulant therapy with less bleeding complications in the long-term treatment of deep venous thrombosis (DVT). One hundred consecutive elderly patients (>75 years old) with venographically demonstrated proximal DVT were included in a randomized trial. All patients were treated for ten days with adjusted doses of intravenous heparin. Informed consent was obtained and on the eight day, patients were randomly allocated to receive acenocoumarol (INR 2.0-3.0) or subcutaneous enoxaparin (4000 anti-Xa units once a day) for three months. All patients were followed-up clinically and venographically for a one year period. The results were analyzed with Fisher's exact test or chi-square test as appropriate. During the treatment and surveillance period, 6 of the 50 patients (12%) who received acenocoumarol and 8 of the 50 patients (16%) who received enoxaparin had new episodes of venous thromboembolism confirmed by objective testing (p = 0.6; 95% CI for the difference: -19.5 to 11.5). Hemorrhagic complications occurred in six of the 50 patients (12%) who received acenocoumarol and in one (2%) of those on enoxaparin (p = 0.1; 95% CI for the difference: -1.8 to 21.8). Vertebral fractures developed in 2 patients (4%) in the enoxaparin group (p = 0.5; 95% CI for the difference: -11.4 to 3.4). These results show that fixed dose enoxaparin seems to be effective and safe in the long-term treatment of proximal DVT in the elderly. In comparison with oral anticoagulants, the findings are inconclusive due to the wide confidence intervals for differences between outcomes, however they suggest that the former may have less bleeding complications with similar efficacy.     

Thromboprophylaxis in cancer patients with central venous catheters. A systematic review and meta-analysis

It was the aim of the review to determine the risks and benefits of primary thromboprophylaxis with anticoagulants in cancer patients with central venous devices. Medline, Central and Google Scholar databases were searched for randomized controlled trials (RCTs) in June 2006. Two reviewers extracted data and appraised the quality of RCTs. Results were expressed as relative risk (RR) with 95% confidence intervals (CI) using random effects model for the outcomes of catheter-related thrombosis, bleeding and thrombocytopenia. Eight RCTs (1,428 patients) were included. There was no statistically significant difference in the risk of catheter-related thrombosis for the use of warfarin versus placebo (3 trials, 425 patients, RR 0.75, 95% CI 0.24-2.35, p = 0.63), heparin versus placebo (4 trials, 886 patients, RR 0.46 95% CI 0.18-1.20, p = 0.06) or warfarin, unfractionated heparin or low-molecular-weight heparin versus placebo (7 trials, 1,311 patients, RR 0.59, 95% CI 0.31-1.13, p = 0.11). Substantial statistical heterogeneity was noted among these trials (I(2) > 50%). The use of anticoagulants showed no statistically significant difference in the risk of overall bleeding (5 trials, 1,193 patients, RR 1.24, 95% CI 0.84-1.82, p = 0.28), and thrombocytopenia for heparin versus placebo (4 trials, 958 patients, RR 0.85, 95% CI 0.49, 1.46, p = 0.55) without any statistical heterogeneity (I(2) = 0%). In cancer patients with central venous devices, thromboprophylaxis has no significant effect on the risk of catheter related thrombosis or bleeding. The use of primary thromboprophylaxis in cancer patients with central venous catheters while not causing any harm provides no benefit.     

Prevention of central venous line-related thrombosis by continuous infusion of low-dose unfractionated heparin, in patients with haemato-oncological disease. A randomized controlled trial

We have conducted a prospective randomized controlled trial to evaluate the role of low-dose unfractionated heparin prophylaxis in preventing central venous line-related thrombosis in patients with haemato-oncological disease. Patients were randomly assigned to receive either prophylactic intravenous unfractionated heparin (continuous infusion of 100 IU/kg/daily) or 50 ml/daily of normal saline solution as a continuous infusion. CVLs were externalized, non tunneled, double lumen catheters. All CVLs were placed percutaneously by the same physician in the subclavian vein. Upper limb veins were systematically examined by ultrasonography just before, or <24 hours after, catheter removal, and in case of clinical signs of thrombosis. One hundred and twenty-eight CVLs were inserted. Catheter-related thrombosis occurred in 1.5% of the catheters inserted in patients of the heparin group, and in 12.6% in the control group (p = 0.03). No other risk factors were found for the development of catheter-related thrombosis. Two and three patients experienced severe bleeding in the heparin group, and in the control group, respectively (p = 0.18). There were no other side-effects clearly ascribable to the use of unfractionated heparin. This is the first prospective, randomized study, which shows that low-dose of unfractionated heparin is safe and effective to prevent catheter-related thrombosis in patients with haemato-oncological disease.     

Lipoprotein (a) in patients with spontaneous venous thromboembolism

INTRODUCTION: Elevated lipoprotein (a) (Lp (a)) has been established as a risk factor of coronary heart disease and stroke. Findings concerning the risk of venous thromboembolism (VTE) in adults are contradictory. The aim of our study was to investigate, whether elevated Lp (a) levels are an independent risk factor of spontaneous symptomatic venous thromboembolism (VTE). Our study was further designed to detect differences in risk profiles between thrombosis patients with and without symptomatic PE. MATERIALS AND METHODS: We investigated Lp (a) in 128 patients with spontaneous symptomatic deep vein thrombosis (DVT, group 1), 105 with spontaneous symptomatic pulmonary embolism with or without DVT (PE, group 2) and 122 healthy controls. Lp (a) was measured with an immunoturbidimetric assay (Tina-quant(R), Roche, Grenzach-Wyhlen, Germany) on a Hitachi-Modular system. RESULTS: Lp (a) levels (mg/L) were not significantly different among groups, median levels (25th-75th percentiles) were 170 (51-386) in group 1, 140 (<20-427) in group 2 and 126 (54-331) in controls, respectively. As continuous variable, odds ratios for VTE for a 100 mg/L increase of Lp (a) were 1.1 [95% confidence interval 0.98-1.2] for group 1 versus controls and 1.1 [0.95-1.2] for group 2 versus controls. The prevalence of Lp (a) above 300 mg/L was not significantly different among patients and controls (group 1: 30%, group 2: 32% and controls: 25%, p=0.4, p=0.2, respectively). CONCLUSIONS: In conclusion we found no association between Lp (a) and VTE regardless whether DVT occurred together with PE or not.     

Elevated white blood cell count and outcome in cancer patients with venous thromboembolism. Findings from the RIETE Registry

A significant association between elevated white blood cell (WBC) count and mortality in patients with cancer has been reported, but the predictive value of elevated WBC on mortality in cancer patients with acute venous thromboembolism (VTE) has not been explored. RIETE is an ongoing registry of consecutive patients with acute VTE. We compared the three-month outcome of cancer patients with acute VTE according to their WBC count at baseline. As of May 2007, 3805 patients with active cancer and acute VTE had been enrolled in RIETE. Of them, 215 (5.7%) had low- (<4,000 cells/microl), 2,403 (63%) normal- (4,000-11,000 cells/microl), 1,187 (31%) elevated (>11,000 cells/microl) WBC count. During the study period 190 patients (5.0%) had recurrent VTE, 156 (4.1%) major bleeding, 889 (23%) died (399 of disseminated cancer, 113 of PE, 46 of bleeding. Patients with elevated WBC count at baseline had an increased incidence of recurrent VTE (odds ratio [OR]: 1.6; 95% confidence interval [CI]: 1.2-2.2), major bleeding (OR: 1.5; 95% CI: 1.1-2.1) or death (OR: 2.7; 95% CI: 2.3-3.2). Most of the reported causes of death were significantly more frequent in patients with elevated WBC count. Multivariate analysis confirmed that elevated WBC count was independently associated with an increased incidence of all three complications. In conclusion, cancer patients with acute VTE and elevated WBC count had an increased incidence of VTE recurrences, major bleeding or death. This worse outcome was consistent among all subgroups and persisted after multivariate adjustment.     

Markers of platelet activation and platelet-leukocyte interaction in patients with myeloproliferative syndromes

INTRODUCTION: Changes in platelet count and function contribute to thrombo-hemorrhagic episodes in chronic myeloproliferative syndromes (MPS). We used flow cytometry to study platelet-leukocyte conjugates and markers of platelet activation in patients with MPS. METHODS: Whole blood from patients with chronic myelogenous leukemia (CML), polycythemia vera (PV), chronic myelofibrosis (MF), and essential thrombocythemia (ET) and from healthy volunteers was prepared for flow cytometry. Platelet microparticles and platelet microaggregates were identified with anti-CD42b and forward scatter, activated platelets with anti-CD62p. Anti-CD42b, anti-CD14, and anti-CD45 were used to study platelet-leukocyte conjugates. RESULTS: The percentage of CD62p-positive platelets was elevated in all myeloproliferate syndrome subtypes. The median percentage of platelet microparticles was 5.2% in controls and significantly higher in PV (12.0%), MF (11.0%), and ET (11.0%, all p<0.05). There was an increased percentage of platelet-neutrophil conjugates in patients with PV (8.3%) and ET (10.4%) compared to normal controls (6.8%, all p<0.05). Platelet-monocyte conjugates were 8.0% in controls and elevated in PV (15.4%) and ET (15.0%, all p<0.05). Patients with a history of venous or arterial thrombotic events had slightly less platelet-leukocyte conjugates and slightly more microparticles than patients without thrombosis; however, this difference was not statistically significant. CONCLUSIONS: These findings suggest that platelet-leukocyte conjugate formation occurs in myeloproliferative syndromes and indicates platelet activation. Also, platelet microparticles are elevated and might provide a catalytic surface for thrombin generation. This could explain the clinical observation that patients with myeloproliferative syndromes have an increased risk to experience arterial or venous thrombotic events.     

Factor V Leiden mutation and pregnancy-related venous thromboembolism: what is the exact risk? Results from a meta-analysis

The magnitude of the association of factor V Leiden mutation with pregnancy-related venous thrombosis remains unclear. Our objective was to undertake a systematic review and a metaanalysis of the literature to estimate precisely the association of factorV Leiden mutation with the risk of first, or recurrent, pregnancy-related venous thromboembolism. Studies published before October 2005 were identified by Medline((R)). Using both fixed and random effect models, odds ratios (OR) with accompanying 95% confidential intervals (CI) were calculated for the factor V Leiden mutation and the clinical end-point (Yusuf-Peto adaptation of the Mantel-Haenszel, DerSimonian and Laird method). We identified 13 studies including 7 cohorts and 6 casecontrol studies relating to factor V Leiden and pregnancy-related venous thrombosis. The results from the cohorts showed a pooled OR of 4.46 (95% CI, 1.82-10.94; 7,879 pooled women), with no evidence of statistical heterogeneity (p = 0.36), for the risk of a first venous thromboembolism during pregnancy or the postpartum period associated with the factor V Leiden mutation. Case-control studies revealed a higher risk (OR 8.6, 95% CI, 5.85-12.63; 1,433 [corrected] pooled women) with significant heterogeneity (p < 0.005). Because of insufficient data, an analysis for the risk of recurrence could not be performed. Our findings emphasize the fact that limited data are available on this topic. This meta-analysis provides clinicians with an estimate of the average risk of a first thrombosis occurring during pregnancy in women carrying the factor V Leiden to assist the management of such women.     

Predictive factors of bleeding and thrombosis during induction therapy in acute promyelocytic leukemia-a single center experience in 34 patients

In this retrospective study, the hemorrhagic and thrombotic events are reported at presentation and during induction in 34 consecutive acute promyelocytic leukemia (APL) patients treated in a single referral center. The most consistent hemostatic abnormality was decreased fibrinogen level (<150 mg/dL) found in 21 patients (61%), partial thromboplastin time (PTT) was normal almost in all patients. A mildly prolonged prothrombin time (PT) was observed in 14 patients (44%). Median platelet count was 30.10(9)/L (range 3-191.10(9)/L). Life-threatening bleeding manifestations occurred in 10 patients (29%). By multivariate analysis, severe bleeding complications did not correlate with hemostatic parameters but did correlate with white cell count at presentation. Four patients (12%) had severe thrombotic events, two cerebral sagital sinus thrombosis, one pulmonary embolism, and one subclavian vein thrombosis. Two other patients had pseudotumor cerebri. Three out of six patients with thrombotic events were found to have thrombophilia. These results may suggest an association between thrombophilia and thrombosis in APL patients. Two patients suffered from combined severe bleeding and thrombosis. Hemostatic parameters are not helpful in predicting neither hemorrhage nor thrombosis.     

Prevalence of prothrombin G20210A, factor V G1691A (Leiden), and methylenetetrahydrofolate reductase (MTHFR) C677T in seven different populations determined by multiplex allele-specific PCR.

Individuals belonging to six racial groups (African American, Asian Indian, Caucasian, Hispanic, Korean, Native American), and a seventh group comprised of referred patients with thrombosis were genotyped for the prothrombin G20210A mutation, the factor V G1691A (Leiden) mutation, and the methylenetetrahydrofolate reductase (MTHFR) C677T mutation by multiplexed allele-specific PCR. The prothrombin 20210A and factor V 1691A allele frequencies in the thrombosis patients, 3.2% and 9.5%, were significantly higher than those in the random Caucasians, 1.3% and 1.8%, (p = 0.043 and p <0.001, respectively). The relative risk of venous thrombosis was determined to be 2.4-fold for carriers of the prothrombin 20210A allele (odds ratio = 2.54; 95% confidence interval = 0.94, 6.82) and 4.5-fold for carriers of the factor V 1691A allele (odds ratio = 5.06; 95% confidence interval = 2.25, 11.36). Among the seven populations, significant differences were observed in the MTHFR 677T allele distribution, however this mutation was not determined to be a risk factor for venous thrombosis in the patient group studied, either alone or in combination with the prothrombin 20210A and/or the factor V 1691A allele(s).