Rationale and design of a clinical trial of a low-molecular-weight heparin in preventing clinically important venous thromboembolism in medical patients: the prospective evaluation of dalteparin efficacy for prevention of venous thromboembolism in immobilized patients trial (the PREVENT study)

The utility of low-molecular-weight heparin (LMWH) in the prophylaxis of venous thromboembolic disease has been examined using the surrogate endpoint of venographically identified thrombi. The largest portion of these thrombi were asymptomatic calf-vein thrombi. The clinical relevance of this observation is a matter of debate. The present study is designed to evaluate the impact of an LMWH on clinically important endpoints. The current study is a randomized, prospective, double-blinded, multicenter, multinational, controlled clinical trial comparing dalteparin with placebo in moderately high-risk hospitalized medical patients. A total of 3300 patients will be randomized to receive either 5,000 IU per day of dalteparin or placebo for 14 days. Patients will undergo appropriate evaluation for any symptomatic episodes and all patients will undergo a bilateral compression ultrasound (CUS) on day 21 to search for asymptomatic proximal thrombi. The primary endpoint is the combination of objectively confirmed symptomatic deep vein thrombi (DVT), fatal or non-fatal pulmonary emboli, all proximal DVT, and sudden death. This study will be the first study to examine clinically important endpoints in evaluating the effect of a LMWH in hospitalized medical patients. This study also is the first study to use CUS rather than venography in concordance with contemporary medical practice. This trial is thus designed to address this important question in a clinically relevant manner.     

Predictors and safety of venous thromboembolism prophylaxis among hospitalized inflammatory bowel disease patients

IntroductionInflammatory bowel disease (IBD) patients are at increased risk of venous thromboembolism (VTE) especially during hospitalization. We assessed the safety and predictors of VTE prophylaxis in this population.MethodsWe conducted a retrospective study of 974 IBD admissions between February 2010 and May 2012. We abstracted data on clinical characteristics, VTE prophylaxis and bleeding events, and conducted multivariate analysis to determine predictors of prophylaxis.ResultsPharmacological VTE prophylaxis was administered to 80% of admissions; 63% were within 24 h of admission. Patients on the surgical service (adjusted OR [aOR], 3.82; 95% CI: 2.00–7.29) and general medicine (aOR, 2.40; 95% CI: 1.39–4.12) were more likely to receive VTE prophylaxis compared to those on the gastroenterology service. Rectal bleeding on admission was associated with lower prophylaxis (aOR, 0.58; 95% CI: 0.35–0.97). The VTE prophylaxis rate increased from 47% to 73% (P < 0.001) on non-surgical services with the introduction of a pharmacist advocate. The rates of major and minor bleeding were similar between patients who did and did not receive VTE prophylaxis (0.26 vs. 0 per 1000 person-days, P = 0.7; 4.18 vs. 2.53 per 1000 person-days, P = 0.4 respectively), and the major bleeding events (n = 2) were post-operative. VTE prophylaxis was not associated with major postoperative bleeding (0.4% vs. 0%, P = 0.96).ConclusionsVTE prophylaxis was more frequent on the surgical service, where standardized protocols exist. The introduction of a pharmacist advocate greatly increased VTE prophylaxis on the non-surgical services. Prophylactic anticoagulation is safe in IBD despite the presence of rectal bleeding on admission.     

Safety of dalteparin for the prophylaxis of venous thromboembolism in elderly medical patients with renal insufficiency: a pilot study

The aim of this prospective cohort study was to determine the incidence of dalteparin bioaccumulation (measured using anti-Xa levels), and bleeding during thromboprophylaxis in elderly patients with renal failure who were admitted to hospital with an acute medical illness. Patients who met the criteria for being at high thromboembolic risk received dalteparin 5,000 IU subcutaneously once daily while the other patients (low risk) received 2,500 IU daily. Thromboprophylaxis was administered for at least 6 days. Anti-Xa activity was determined before the first dalteparin dose and again on day 6, 4 hours after the administration of the dalteparin dose. Bleeding was assessed daily. Compression ultrasonography was performed to identify any deep vein thromboses. There was no evidence of bioaccumulation on day 6 of therapy, irrespective of renal function. No episodes of major bleeding or venous thromboembolism occurred. Larger, randomized studies are warranted to confirm the safety of dalteparin in this patient population.     

Risk-assessment models for predicting venous thromboembolism among hospitalized non-surgical patients: a systematic review

Venous thromboembolism (VTE) prophylaxis is suboptimal in American hospitals despite long-standing evidence-based recommendations. Data from observational studies indicate a lower uptake of effective prophylaxis in patients hospitalized with medical versus surgical conditions. Reluctance to use prophylaxis in medical patients has been attributed to difficulty in identifying at-risk patients and balancing risks of bleeding against occurrence of VTE. Several risk-assessment models (RAMs) have been proposed to assist physicians in identifying non-surgical patients who need prophylaxis. We conducted a systematic review of published RAMs, based on objective criteria, to determine whether any RAM is validated sufficiently to be employed in clinical practice. We identified 11 RAMs, six derived from primary data and five based on expert opinion. The number, types, and strength of association of VTE risk predictors were highly variable. The variability in methods and outcome measurement precluded pooled estimates of these different models. Published RAMs for VTE lack generalizability and adequate validation. As electronic health records become more ubiquitous, validated dynamic RAMs are needed to assess VTE risk at the point-of-care in real time.     

Comparison of two escalated enoxaparin dosing regimens for venous thromboembolism prophylaxis in obese hospitalized patients

Journal of Thrombosis and Thrombolysis - Standard fixed-dose enoxaparin dosing regimens may not provide adequate prophylaxis against venous thromboembolism among obese hospitalized patients. While...     

Renal function and clinical outcome of patients with cancer-associated venous thromboembolism randomized to receive apixaban or dalteparin. Results from the Caravaggio trial

The effect of renal impairment (RI) on risk of bleeding and recurrent thrombosis in cancer patients treated with direct oral anticoagulants for venous thromboembolism (VTE) is undefined. We ran a prespecified analysis of the randomized Caravaggio study to evaluate the role of RI as a risk factor for bleeding or recurrence in patients treated with dalteparin or apixaban for cancer-associated VTE. RI was graded as moderate (creatinine clearance between 30-59 mL/minute; 275 patients) and mild (between 60-89 mL/minute; 444 patients). In the 1142 patients included in this analysis, the incidence of major bleeding was similar in patients with moderate vs. no or mild RI (HR 1.06-95% CI: 0.53-2.11), with no difference in the relative safety of apixaban and dalteparin. Recurrent VTE was not different in moderate vs. no or mild RI (HR=0.67, 95% CI: 0.38-1.20); in moderate RI, apixaban reduced recurrent VTE compared to dalteparin (HR=0.27, 95% CI: 0.08-0.96; P for interaction 0.1085). At multivariate analysis, no association was found between variation of renal function over time and major bleeding or recurrent VTE. Advanced or metastatic cancer was the only independent predictor of major bleeding (HR=2.84, 95% CI: 1.20-6.71), with no effect of treatment with apixaban or dalteparin. In our study, in cancer patients treated with apixaban or dalteparin, moderate RI was not associated with major bleeding or recurrent VTE. In patients with moderate renal failure, the safety profile of apixaban was confirmed with the potential for improved efficacy in comparison to dalteparin. ClinicalTrials.gov identifier: {"type":"clinical-trial","attrs":{"text":"NCT03045406","term_id":"NCT03045406"}}NCT03045406.     

Prevention of venous thromboembolism in medical patients with enoxaparin: a subgroup analysis of the MEDENOX study.

The Medical Patients with Enoxaparin (MEDENOX) trial was a randomized, placebo-controlled study that defined the risk of venous thromboembolism (VTE) in acutely ill, immobilized, general medical patients and the efficacy of the low-molecular-weight heparin, enoxaparin, in preventing thrombosis. We performed a post-hoc analysis to evaluate the effect of 40 mg enoxaparin once daily on MEDENOX patient outcome in different types of acute medical illness (heart failure, respiratory failure, infection, rheumatic disorder and inflammatory bowel disease) and pre-defined risk factors (chronic heart and chronic respiratory failure, age, immobility, previous VTE and cancer). The primary outcome was the occurrence of documented VTE between days 1 and 14. The relative risk reduction [95% confidence intervals (CI)] for VTE comparing 40 mg enoxaparin with placebo in the subgroups were: acute heart failure, 0.29 (95% CI, 0.10-0.84); acute respiratory failure, 0.25 (95% CI, 0.10-0.65); acute infectious disease, 0.28 (95% CI, 0.09-0.81); and acute rheumatic disorder, 0.48 (95% CI, 0.11-2.16). The relative risk reduction for VTE in the pre-defined risk factor subgroups were: chronic heart failure, 0.26 (95% CI, 0.08-0.92); chronic respiratory failure, 0.26 (95% CI, 0.10-0.68); age, 0.22 (95% CI, 0.09-0.51); immobility, 0.53 (95% CI, 0.14-1.72); previous VTE, 0.49 (95% CI, 0.15-1.68); and cancer, 0.50 (95%o CI, 0.14-1.72). The beneficial effects of enoxaparin extend to a wide range of acutely ill medical patients.     

Inverse relationship of serum albumin to the risk of venous thromboembolism among acutely ill hospitalized patients: Analysis from the APEX trial

Hypoalbuminemia is a common finding and independent predictor for unfavorable prognosis. The prognostic value of albumin measurement for short-term VTE prediction in hospitalized patients remains unclear. In the APEX trial ( ClinicalTrials.gov identifier: NCT01583218), medical inpatients were randomized to receive either extended-duration betrixaban or shorter-duration enoxaparin and followed for 77 days. Baseline albumin concentrations were obtained in 7266 subjects with evaluable VTE endpoints. The association of baseline albumin to VTE was assessed, with adjustment for patient characteristics, thromboprophylaxis, and biomarkers for fibrinolysis and inflammation (ie, D-dimer and C-reactive protein [CRP]). VTE risk refinement was evaluated by incorporation of albumin to well-validated risk assessment models. A stepwise increase in the risk of VTE (P < .0001) was observed with lower levels of albumin. Patients at the bottom albumin quartile (<35 g/L) had a two-fold greater odds for developing VTE compared with the top quartile (≥42 g/L) (OR = 2.119 [95% CI, 1.592-2.820]; adjusted OR = 2.079 [1.485-2.911]). The odds for VTE increased by 1.368 (95% CI, 1.240-1.509) times per SD decrement of albumin (5.24 g/L). Compared with the propensity score-matched pairs of patients with albumin ≥35 g/L, patients with albumin <35 g/L had a greater risk of VTE (OR = 1.623 [1.260-2.090]; adjusted OR = 1.658 [1.209-2.272]). Albumin measurement also refined VTE risk discrimination and reclassification after inclusion in the risk assessment models. In conclusion, acutely ill hospitalized patients with low serum albumin had an increased VTE risk through 77 days. VTE risk assessment models for medical inpatients should consider incorporation of baseline albumin measurement.     

Efficacy of tiotropium in COPD patients from Asia: a subgroup analysis from the UPLIFT trial

Background and objective: Studies in respiratory diseases other than chronic obstructive pulmonary disease suggest potentially differing responses to medications among patients from different regions. We report a subgroup analysis of patients recruited to Asian centres from a previously reported 4‐year COPD trial. Methods: Subgroup analysis from a randomized, double‐blinded, placebo‐controlled trial of tiotropium 18 µg daily in COPD. Primary end‐point was rate of decline in FEV₁. Secondary end‐points included spirometry at individual time points, health‐related quality of life (St George's Respiratory Questionnaire), exacerbations and mortality. Results: Of 5992 patients, 362 were from Asian centres (100 from Japan). Mean age 66 years, 95% men, 13% current smokers, BMI: 21 kg/m²; post‐bronchodilator FEV₁: 44% predicted; St George's Respiratory Questionnaire total score: 44 units. No treatment effect was observed for rate of decline in FEV₁ although annual decline was less in Asian patients. Morning pre‐bronchodilator FEV₁ and forced vital capacity improved in Asian patients (P < 0.05). Tiotropium reduced number of exacerbations (rate ratio (95% confidence interval (CI)): 0.73 (0.57–0.94)). Hazard ratios (95%CI) for exacerbations and hospitalized exacerbations (tiotropium/control) were 0.81 (0.62–1.05) and 0.85 (0.61–1.19), respectively. St George's Respiratory Questionnaire total score improved by 1.5–6.1 units (P < 0.05 for months 18, 24, 30 and 36) with tiotropium. Fatal events occurred in 34 tiotropium (18.5%) and 42 control (23.6%) patients. Conclusions: In COPD patients from Asia, tiotropium improves lung function, improves health‐related quality of life and reduces exacerbations over 4 years of treatment.     

Effectiveness and safety of rivaroxaban versus warfarin in obese patients with acute venous thromboembolism: analysis of electronic health record data

Journal of Thrombosis and Thrombolysis - There is limited data evaluating clinical outcomes of rivaroxaban versus warfarin in obese patients with venous thromboembolism (VTE). Our objective was to...     

国产低分子量肝素治疗静脉血栓栓塞症的有效性和安全性研究

低分子量肝素（low molecular weight heparin, LMWH）由普通肝素经各种方法裂解而来,其平均分子量为4～6．5ku。LMWH通过与抗凝血酶Ⅲ（ATⅢ）结合,使ATⅢ的抗凝活性增加2000倍,有很强灭活凝血酶Ⅹa因子的作用．而抗Ⅱa活性低．其抗Ⅹa：抗Ⅱa约为2：1至4：1．因此LMWH主要通过抗Ⅹa因子发挥抗凝作用。     

Efficacy and safety of low-dose clopidogrel in Japanese patients after drug-eluting stent implantation: a randomized pilot trial

In Japan, a lower maintenance dose of ticlopidine is used than in the United States and Europe. Therefore a lower maintenance dose of clopidogrel may also be considered appropriate in Japanese patients. The present randomized pilot study evaluated the efficacy and safety of 50 mg clopidogrel in Japanese patients who underwent drug-eluting stent (DES) implantation. A total of 200 patients with 277 lesions who underwent intravascular ultrasound-guided DES implantation were enrolled. The subjects were allocated to the 50- or 75-mg clopidogrel group. All patients received 100 mg aspirin daily before the procedure, and this continued indefinitely. The duration of clinical follow-up was 21.8 ± 5.7 months in the 75-mg group and 21.9 ± 6.1 months in the 50-mg group (P = 0.96). During follow-up, no cardiac death, myocardial infarction, or stent thrombosis was observed in either group. Side effects of clopidogrel were observed in 4 patients (4.0 %) in the 75-mg group and in 4 patients (4.0 %) in the 50-mg group. Following this randomized pilot study, it may be justified to perform a large-scale randomized study comparing 50- and 75-mg dosing of clopidogrel in Japanese patients undergoing coronary stent implantation.     

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内外科住院患者深静脉血栓栓塞(VTE)的风险在增高,成为住院死亡的重要原因和沉重经济负担。大部分VTE与基础疾病及治疗措施有关,预防措施可以安全有效减低VTE发生。文章介绍了《内科住院患者深静脉血栓栓塞预防的中国专家建议》的相关内容。     

Emerging strategies in the prevention of venous thromboembolism in hospitalized medical patients

Venous thromboembolism (VTE) remains a significant cause of morbidity and mortality in hospitalized patients with acute medical illness. The high prevalence of VTE in this patient population, its clinically silent nature, and associated morbidity and mortality indicate that prophylactic therapy is appropriate in those determined to be at increased risk. Unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) have been shown to reduce the incidence of VTE and are the primary therapies used for prophylaxis in these patients. Although both UFH and LMWH have received grade 1A recommendations for the prevention of VTE in at-risk medical patients in the 2004 American College of Chest Physicians consensus conference statements, LMWH has advantages over UFH in its once-daily dosing scheme, reduced incidence of major and minor bleeding events, and reduced incidence of heparin-induced thrombocytopenia. Fondaparinux is a novel antithrombotic agent characterized by specificity for factor Xa and a lack of platelet interaction. A recent clinical trial in hospitalized patients with acute medical illness found that fondaparinux significantly reduced the incidence of both VTE and fatal pulmonary embolism compared with placebo, without increased major bleeding. Despite the availability of effective thromboprophylactic therapies, VTE prophylaxis continues to be underutilized in hospitalized medical patients.     

Risk stratification for venous thromboembolism in hospitalized patients in a developing country: a prospective study

Venous Thrombo-Embolism (VTE) is a serious complication in hospitalized patients but can be preventable. This prospective study addresses risk factors assessment and the use of heparin in this population. About 2,496 non pediatric patients were admitted to Jordan University Hospital between June 12, 2007 and July 19, 2007. A random sample of 624 patients consisting of every fourth admission was chosen. The stratification of risk factors was assessed using Caprini model and the ACCP score. The mean age of the patients (229 males and 395 females) was 45.34 ± 18.3 years. More than 80% of the admitted patients were considered at high risk for VTE but heparin was used in only 26% of the patients. The majority of our patients constitute a high-risk population. Implementation of strategies including educational sessions and risk stratification guidelines can reduce the incidence, morbidity, and mortality of VTE especially in developing countries.     

Venous thromboembolism prophylaxis in hospitalized elderly patients： Time to consider a ＇MUST＇ strategy

Venous thromboembolism (VTE) is the commonest cause of preventable death in hospitalized patients. Elderly patients have higher risk of VTE because of the high prevalence of predisposing co-morbidities and acute illnesses. Clinical diagnosis of VTE in the elderly patient is particularly difficult and, as such, adequate VTE prophylaxis is of pivotal importance in reducing the mortality and morbidities of VTE. Omission of VTE prophylaxis is, however, very common despite continuous education. A simple way to overcome this problem is to implement universal VTE prophylaxis for all hospitalized elderly patients instead of selective prophylaxis for some patients only according to individual’s risk of VTE. Although pharmacological VTE prophylaxis is effective for most patients, a high prevalence of renal impairment and drug interactions in the hospitalized elderly patients suggests that a multimodality approach may be more appropriate. Mechanical VTE prophylaxis, including calf and thigh compression devices and/or an inferior vena cava filter, are often underutilized in hospitalized elderly patients who are at high-risk of bleeding and VTE. Because pneumatic compression devices and thigh length stockings are virtually risk free, mechanical VTE prophylaxis may allow early or immediate implementation of VTE prophylaxis for all hospitalized elderly patients, regardless of their bleeding and VTE risk. Although the cost-effectiveness of this Multimodality Universal STat (‘MUST’) VTE prophylaxis approach for hospitalized elderly patients remains uncertain, this strategy appears to offer some advantages over the traditional ‘selective and single-modal’ VTE prophylaxis approach, which often becomes ‘hit or miss’ or not implemented promptly in many hospitalized elderly patients. A large clustered randomized controlled trial is, however, needed to assess whether early, multimodality, universal VTE prophylaxis can improve important clinical outcomes of hospitalized elderly patients.     

Pharmacological venous thromboembolism prophylaxis in hospitalized medical patients: a meta-analysis of randomized controlled trials

BACKGROUND: There is uncertainty regarding which pharmacological agents most effectively prevent venous thromboembolism in hospitalized medical patients. We therefore performed a meta-analysis to determine this. METHODS: MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched from 1950, 1966, and 1800, respectively, through June 30, 2006, for randomized controlled trials that involved medical patients comparing unfractionated heparin (UFH) or low-molecular-weight heparin or heparinoid (LMWH) with a control, LMWH with UFH, or selective factor Xa inhibitors with a comparator. Study selection, validity assessment, and data abstraction were performed by 2 independent reviewers (L.W. and S.W.). Data synthesis was undertaken by 1 blinded investigator (S.J.H.). RESULTS: Thirty-six studies were included. Compared with the control, UFH was associated with a reduced risk of deep venous thrombosis (DVT) (risk ratio [RR], 0.33; 95% confidence interval [CI], 0.26-0.42) and pulmonary embolism (RR, 0.64; 95% CI, 0.50-0.82), as was LMWH (RR, 0.56; 95% CI, 0.45-0.70; and RR, 0.37; 95% CI, 0.21-0.64, respectively). A UFH dosage of 5000 U 3 times daily was more effective in preventing DVT than a UFH dosage of 5000 U twice daily when compared with the control (RR, 0.27; 95% CI, 0.20-0.36; vs RR, 0.52; 95% CI, 0.28-0.96). Neither UFH nor LMWH reduced mortality. When directly compared with UFH, LMWH was associated with a lower risk of DVT (RR, 0.68; 95% CI, 0.52-0.88) and injection site hematoma (RR, 0.47; 95% CI, 0.36-0.62), but no difference was seen between the 2 agents in the risk of bleeding or thrombocytopenia. CONCLUSIONS: Both UFH and LMWH reduce venous thromboembolic risk in hospitalized medical patients, but neither agent alters mortality. When directly compared, LMWH is more effective in preventing DVT.