Assessment of clinically relevant bleeding as a surrogate outcome for major bleeding: validation by meta-analysis of randomized controlled trials.

Essentials Surrogacy of clinically relevant bleeding (CRB) for major bleeding has never been validated. Our meta-analysis evaluated CRB surrogacy in trials of new versus traditional anticoagulants. Surrogacy was not validated in orthopedic surgery, venous thromboembolism or atrial fibrillation The difficulty in demonstrating the surrogacy may reflect a lack of homogeneity in its definition SUMMARY: Background Clinically relevant bleeding (CRB), comprising major bleeding and clinically relevant non-major bleeding, has been used as a surrogate for major bleeding in most anticoagulant trials. The validity of this surrogate to estimate trade-off between thrombotic and bleeding events in clinical trials was never assessed. Methods We systematically reviewed randomized phase III trials comparing new anticoagulants with the standard of care for venous thromboembolism prevention following major orthopedic surgery, venous thromboembolism (VTE) treatment, or stroke and systemic embolism prevention in atrial fibrillation (AF), and reporting both major bleeding and CRB rates. The validity of CRB as a surrogate for major bleeding was assessed according to the strength of the association between the relative risks of major bleeding and CRB, measured by the use of R2trial and its 95% confidence interval (CI). Results In the postoperative prophylactic setting (13 studies), major bleeding and CRB rates were 1.12% and 3.56%, respectively, and R2trial was 0.69 (95% CI 0.34-0.93). For acute VTE studies (n = 12), major bleeding and CRB rates were 1.87% and 9.07%; the corresponding R2trial values were 0.28 (95% CI 0.01-0.80) and 0.68 (95% CI 0.09-1.00) when only double-blind studies were considered (n = 7). For AF studies (n = 7; 22 strata), major bleeding and CRB rates were 4.82% and 15.3%, and R2trial was 0.59 (95% CI 0.15-0.82). Conclusion Despite an apparent correlation between CRB and major bleeding in major orthopedic surgery, AF, and double-blind acute VTE studies, the wide CIs suggest that CRB might not be an acceptable surrogate outcome in any of these settings.

[General medicine management of superficial venous thrombosis of the lower limbs: A survey in Saône-et-Loire]. / Prise en charge en médecine générale des thromboses veineuses superficielles des membres inférieurs. Enquête en Saône-et-Loire.

CONTEXT: For a long time, superficial venous thrombosis (SVT) of the lower limbs was considered as benign. Due to lack of clear scientific evidence, its treatment was heterogeneous and even potentially deleterious. Since 2010, several major studies have highlighted the seriousness of SVT, and prophylactic doses of fondaparinux have proven their efficacy for this indication. While the French recommendations have not yet taken on board all this data, has practice already changed? AIM: To describe in general practice the usual management of suspected SVT. METHODS: A descriptive cross-sectional study of general practitioners in Saône-et-Loire. Each doctor taking part was asked to note on a paper questionnaire the details of the last patient in whom they suspected SVT. Data collected included: clinical presentation, diagnostic and therapeutic management and follow-up of the patients. RESULTS: Between 01/01/2014 and 31/03/2014, 88 doctors out of 443 contacted (20%) completed the questionnaire. According to the information they provided, 36 physicians (40.9% [95% CI: 30.6-50.2]) searched for an associated pulmonary embolism. Eighty-two physicians (93.2% [95% CI: 87.9-98.4]) prescribed a venous compression ultrasound (CUS) exploration. Twelve etiological assessments were carried out (13.6% [95% CI: 6.5-20.8]) of which 6 (6.8%) appeared to be justified. 64 (72.7%) of the patients were given an anticoagulant therapy (heparin or fondaparinux), including 15 (17%) at a prophylactic dose and 49 (55.7%) at a curative dose. Forty-nine doctors (55.7% [95% CI: 45.3-66.1]) prescribed a CUS follow-up. CONCLUSION: General practitioners seem to have adapted their diagnostic practices to the data highlighting the potential seriousness of SVT. The treatment they give, however, remains very variable and potentially deleterious, in particular due to a high rate of treatments given at curative doses.

Spontaneous acute superficial vein thrombosis of the legs: do we really need to treat?

Spontaneous acute superficial vein thrombosis (SVT) of the leg is now generally recognized as an integral component of venous thromboembolic disease with potentially severe consequences. However, the relatively low grades of some current international recommendations and uncertainty regarding the cost-effectiveness of available therapies may prompt questioning of the real need to treat patients with SVT and explain the persisting heterogeneity of their management in practise. Yet several studies have consistently shown high rates of thromboembolic complications associated with SVT, whether at first presentation or during follow-up. The CALISTO trial established for the first time the clinical benefit of a well-defined anticoagulant regimen for the prevention of serious thromboembolic complications in SVT patients, and we believe that patients such as those included in this trial should receive this regimen as tested. However, several areas of uncertainty remain for categories of SVT patients not evaluated in CALISTO.

Annual diagnosis rate of superficial vein thrombosis of the lower limbs: the STEPH community-based study.

BACKGROUND: The incidence of superficial vein thrombosis (SVT) in the general adult population remains unknown. OBJECTIVES: To assess the annual diagnosis rate of symptomatic, objectively confirmed lower limb SVT, associated or not with concomitant deep vein thrombosis and/or symptomatic pulmonary embolism. METHODS/PATIENTS: We conducted, from November 14, 2011, to November 13, 2012, a multicenter, community-based study in the Saint-Etienne urban area, France, representing a population of 265 687 adult residents (according to the 2009 census). All 248 general practitioners located within the area were asked to refer any patient with clinically suspected lower limb acute SVT to a vascular physician for systematic compression ultrasonography. All 28 vascular physicians located within the area participated in the study. The annual diagnosis rate, with the corresponding 95% confidence interval (CI), was calculated as the number of patients with symptomatic, objectively confirmed SVT divided by the number of person-years at risk defined by population data of the area. All venous thromboembolic events were validated by an independent central adjudication committee. RESULTS: Overall, 171 patients with symptomatic, confirmed SVT were reported. The annual diagnosis rate was 0.64& (95% CI, 0.55%-0.74&), was higher in women, and increased with advancing age regardless of gender [corrected]. Concomitant deep vein thrombosis (20 proximal) was observed in 42 patients (24.6% [95% CI, 18.3%-31.7%]), and concomitant symptomatic pulmonary embolism was observed in eight patients (4.7% [95% CI, 2.0%-9.0%]). CONCLUSIONS: This first community-based study showed that symptomatic SVT with confirmed diagnosis is a relatively common disease frequently associated with thromboembolic events in the deep venous system.

Superficial vein thrombosis and recurrent venous thromboembolism: a pooled analysis of two observational studies.

BACKGROUND: The management strategies for symptomatic isolated superficial vein thrombosis (SVT) (without concomitant deep vein thrombosis [DVT] or pulmonary embolism [PE]) have yet to achieve widespread consensus. Concerns have been raised regarding the usefulness of prescribing anticoagulant treatments to all patients with isolated SVT. Determining the isolated SVT subgroups who have the highest risks of venous thromboembolism (VTE) recurrence (composite of DVT, PE, and new SVT) may facilitate the identification of patients who are likely to benefit from anticoagulant treatment. DESIGN AND METHODS: We performed a pooled analysis on individual data from two observational, multicenter, prospective studies, to determine predictors for VTE recurrence and their impact in an unselected population of symptomatic isolated SVT patients. RESULTS: One thousand and seventy-four cases of symptomatic isolated SVT were followed up at 3 months. VTE recurrence was observed in 3.9% of the patients; 16.2% of the patients did not receive anticoagulants, and 0.6% experienced a VTE recurrence. Cancer, personal history of VTE and saphenofemoral/popliteal involvement significantly increased the risk of subsequent VTE or DVT/PE in univariate analyses. Only male sex significantly increased the risk of VTE or DVT/PE recurrence in multivariate analyses. Twelve percent of the patients had cancer or saphenofemoral junction involvement, and were at higher risk of DVT/PE recurrence than patients without those characteristics (4.7% vs. 1.9%, P= 0.06). CONCLUSIONS: In patients with symptomatic SVT, only male sex significantly and independently increased the risk of VTE recurrence. Cancer or saphenofemoral junction involvement defined a population at high risk for deep VTE recurrence. Some SVTs might be safely managed without anticoagulants.

Value of a planned compression ultrasonography after an isolated superficial vein thrombosis: results from a prospective multicentre study.

OBJECTIVES: To assess the efficiency of a systematically planned compression ultrasonography (SP-CUS) to detect venous thrombotic complications (VTCs) in patients with symptomatic isolated superficial vein thrombosis (SVT). DESIGN: Post hoc analysis of a prospective, multicentre, cohort study (POST). PATIENTS: As many as 537 patients with CUS-confirmed isolated SVT undergoing an SP-CUS 8-15 days after the initial CUS. OUTCOMES: Asymptomatic VTC (extension or recurrence of SVT, deep-vein thrombosis (DVT) of the lower limbs) diagnosed by the SP-CUS and symptomatic thromboembolic complications (VTC and pulmonary embolism (PE)) up to 3 months. RESULTS: VTC was suspected before or on the day of the SP-CUS in 18 patients (3.0%). Among the 519 asymptomatic patients (97%) undergoing SP-CUS, this revealed asymptomatic VTC in 12 patients (2.3%; 4 DVT, 4 SVT recurrences, 4 SVT extensions), none of whom subsequently experienced symptomatic thromboembolic events up to 3 months. Among the 507 patients with a normal SP-CUS, 29 (5.7%) presented symptomatic thromboembolic events during follow-up: 2 PE, 7 DVT, 9 SVT recurrences and 11 SVT extensions. CONCLUSIONS: In this study, the SP-CUS detected a few asymptomatic VTC, but failed to identify patients at risk of thromboembolic events during follow-up. Use of an SP-CUS was therefore neither efficient nor cost effective.

Thrombin generation and heparin-induced thrombocytopenia.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a severe complication of heparin therapy. IgG antibodies targeting the platelet factor 4-heparin complex activate platelets and generate microparticles with procoagulant activity. OBJECTIVES: To determine whether the thrombin generation assay is capable of detecting procoagulant activity induced by patient platelet-poor plasma (PPP) in donor platelet-rich plasma (PRP). PATIENTS AND METHODS: We explored two groups of patients; group 1 (n = 23): patients with a positive clinical and biological diagnosis of HIT; group 2 (n = 25): patients with a negative clinical and biological diagnosis of HIT. Mixtures of donor PRP and patient PPP (1:1) were incubated either with unfractionated heparin 0.2 U mL(-1) or with physiological saline. Thrombin generation was assessed by calibrated thrombinography. The effect of heparin on the mixtures was evaluated according to the ratio of the values with and without heparin (wH/woH) of the five thrombogram parameters. RESULTS: With low heparin concentrations, plasma of group 1 activates donor platelets and generates procoagulant activity. A set of three ratios outside the cut-off values corresponds to the 'HIT thrombogram profile', characterized by a highly specific aspect of the thrombogram wH in relation to the thrombogram woH. None of the group 2 patients presented a HIT thrombogram profile. The results of thrombinography correlate well with the results of the platelet aggregation test. CONCLUSION: Our studies illustrate the central paradox of HIT, namely enhancement of thrombin generation in the presence of heparin. The HIT thrombogram profile as it is defined in this study can detect the procoagulant activity of HIT IgG antibodies.

Anti-factor Xa activity of enoxaparin administered at prophylactic dosage to patients over 75 years old.

AIMS: Major bleeding complications with low-molecular-weight heparin (LMWH) treatment have been reported both in clinical studies and during postmarketing surveillance. Monitoring of antifactor Xa (anti-Xa) activities is therefore recommended in special populations often predisposed to renal impairment. The PROPHRE.75 study was conducted to estimate the distribution parameters of anti-Xa activity in the elderly. METHODS: PROPHRE.75 was a prospective study of a cohort of consecutive patients aged >75 years and treated with 4000 IU of enoxaparin once daily for venous thromboembolism prophylaxis. Dosing history and measurements of anti-Xa activity in sparse samples were recorded throughout treatment. The covariates included weight, gender, age, renal function, medical history and concomitant medication. Population parameters and interindividual variability were estimated using NONMEM V software. RESULTS: Anti-Xa activity was studied in 189 patients (mean age 82 +/- 5 years, 22% weighing <50 kg, 50% presenting renal impairment according to the Cockcroft and Gault formula). A first-order input two-compartment model best fitted the data. Clearance was significantly related to body weight and creatinine clearance based on the simplified Modification of Diet in Renal Disease formula, central volume being related to body weight. According to individual Bayesian estimations, 4% of patients presented with a peak anti-Xa activity >1.0 IU ml(-1), but this group did not include the sole patient experiencing a major bleed (0.53%). CONCLUSIONS: Systematic monitoring of anti-Xa activity in elderly patients treated with enoxaparin at prophylactic doses does not seem to be necessary to prevent the occurrence of major bleeding.

Effect of obesity on outcomes after fondaparinux, enoxaparin, or heparin treatment for acute venous thromboembolism in the Matisse trials.

BACKGROUND: Selecting initial anticoagulant dose by patient weight for acute pulmonary embolism and deep vein thrombosis has clinical credibility; however, uncertainty remains regarding how to dose obese patients with newer anticoagulants because outcome data are sparse. OBJECTIVES: To use the Matisse trials' comparison of sc fondaparinux once daily with control heparin therapies (intravenous unfractionated heparin for pulmonary embolism, sc enoxaparin 1 mg/kg b.i.d. for deep vein thrombosis) for initial treatment in order to compare primary outcomes (venous thromboembolism recurrence and major bleeding) in obese patients. PATIENTS AND METHODS: Primary outcomes were compared in subsets composed of patients weighing < or = and > 100 kg and with body mass index (BMI) < 30 and > or = 30 kg/m(2). Medians and ranges for weight and BMI were compared for patients suffering either recurrence or major bleeding. RESULTS: Twenty-two thousand and one patients received fondaparinux and 2217 received enoxaparin or unfractionated heparin. Four hundred and ninety-six patients (11%) weighed > 100 kg and 1216 (28%) had a BMI > or = 30. Treatment groups had similar characteristics. The upper limit in subject weight for recurrence was 166 kg (BMI 58), and for major bleeding 120 kg (BMI 39). The incidences of recurrence and major bleeding were similar for each patient subset of weight and BMI for both fondaparinux and heparin treatment groups. Among patients with a primary outcome, median weights and BMIs were also similar. CONCLUSIONS: The current recommended doses of fondaparinux and heparins for the treatment of venous thromboembolism appear to provide similar protection against recurrence and major bleeding to one another and to obese and non-obese patients.

Prevention of venous thromboembolism in orthopedic surgery with vitamin K antagonists: a meta-analysis.

BACKGROUND: The benefit-to-risk ratio of vitamin K antagonists (VKA), relative to active comparators, especially low-molecular-weight heparins (LMWH), for preventing venous thromboembolism in patients undergoing major orthopedic surgery is debated. OBJECTIVES: We performed a meta-analysis of all randomized trials in orthopedic surgery comparing adjusted doses of VKA to control treatments. PATIENTS AND METHODS: An exhaustive literature search, both manual and computer-assisted, was performed. Studies were selected on the basis of randomization procedure (VKA vs. a control group). At least one of the following outcome measures was to be evaluated: deep vein thrombosis (DVT), pulmonary embolism (PE), death, major hemorrhage or wound hematoma. Four reviewers assessed each article to determine eligibility for inclusion and outcome measures. RESULTS: VKAs were more effective than placebo or no treatment in reducing DVT [567 patients, relative risk (RR) = 0.56, 95% confidence interval (CI) 0.37, 0.84, P < 0.01] and clinical PE (651 patients, RR = 0.23, 95% CI 0.09, 0.59, P < 0.01). These results were obtained at the cost of a higher rate of wound hematoma (162 patients, RR = 2.91, 95% CI 1.09, 7.75, P = 0.03). VKAs were also more effective than intermittent pneumatic compression (534 patients, RR = 0.46, 95% CI 0.25, 0.82, P = 0.009) in preventing proximal DVT. In contrast, VKAs were less effective than LMWH in preventing total DVT and proximal DVT (9822 patients, RR = 1.51, 95% CI 1.27, 1.79, P < 0.001; and 6131 patients, RR = 1.51, 95% CI 1.04, 2.17, P = 0.028, respectively). The differences between VKA and LMWH in major hemorrhage and wound hematoma were not significant. CONCLUSIONS: In patients undergoing major orthopedic surgery, VKAs are less effective than LMWH, without any significant difference in the bleeding risk.

Subcutaneous fondaparinux versus intravenous unfractionated heparin in the initial treatment of pulmonary embolism.

BACKGROUND: The standard initial treatment of hemodynamically stable patients with pulmonary embolism is intravenous unfractionated heparin, requiring laboratory monitoring and hospitalization. METHODS: We conducted a randomized, open-label trial involving 2213 patients with acute symptomatic pulmonary embolism to compare the efficacy and safety of the synthetic antithrombotic agent fondaparinux with those of unfractionated heparin and to document noninferiority in terms of efficacy. Patients received either fondaparinux (5.0, 7.5, or 10.0 mg in patients weighing less than 50, 50 to 100, or more than 100 kg, respectively) subcutaneously once daily or a continuous intravenous infusion of unfractionated heparin (ratio of the activated partial-thromboplastin time to a control value, 1.5 to 2.5), both given for at least five days and until the use of vitamin K antagonists resulted in an international normalized ratio above 2.0. The primary efficacy outcome was the three-month incidence of the composite end point of symptomatic, recurrent pulmonary embolism (nonfatal or fatal) and new or recurrent deep-vein thrombosis. RESULTS: Forty-two of the 1103 patients randomly assigned to receive fondaparinux (3.8 percent) had recurrent thromboembolic events, as compared with 56 of the 1110 patients randomly assigned to receive unfractionated heparin (5.0 percent), for an absolute difference of -1.2 percent in favor of fondaparinux (95 percent confidence interval, -3.0 to 0.5). Major bleeding occurred in 1.3 percent of the patients treated with fondaparinux and 1.1 percent of those treated with unfractionated heparin. Mortality rates at three months were similar in the two groups. Of the patients in the fondaparinux group, 14.5 percent received the drug in part on an outpatient basis. CONCLUSIONS: Once-daily, subcutaneous administration of fondaparinux without monitoring is at least as effective and is as safe as adjusted-dose, intravenous administration of unfractionated heparin in the initial treatment of hemodynamically stable patients with pulmonary embolism.

Poor anticoagulant response to tissue factor pathway inhibitor in patients with venous thrombosis.

Tissue factor pathway inhibitor (TFPI) is of major importance in regulating the coagulation triggering effects of tissue factor. An association between TFPI deficiency and thrombosis has still not been clearly demonstrated. We evaluated the anticoagulant activity of exogenous TFPI added either to the plasma of patients with venous thrombosis (n = 118) or to the plasma of healthy controls similar in terms of mean age and sex ratio (n = 107). A poor anticoagulant response to TFPI, defined as TFPI resistance, was observed in 4.7% of controls and in 11.0% of patients. TFPI resistance was associated with an almost threefold increase in the risk of thrombosis and could therefore represent a novel hemostatic risk factor for venous thrombosis.

Older people included in a venous thrombo-embolism clinical trial: a patients' viewpoint.

BACKGROUND AND OBJECTIVES: despite the numerous publications debating ethical rules of clinical research, older patients' opinions are rarely taken into account. We report on the feelings and memories related by older patients included in a randomised controlled trial. DESIGN AND SETTINGS: a closed-questionnaire was submitted to patients, aged >65 years, who had been included in the randomised trial "PREPIC". PREPIC was a multicentre open trial performed in France, that included 400 patients over 42 months. The aim of PREPIC was to evaluate the benefits and risks of prophylactic filter placement in patients with proximal deep-vein thrombosis who were considered to be at risk for pulmonary embolism. RESULTS: 104 patients (mean age: 74 years) were interviewed. At the time the trial was proposed to them, 45% of patients felt surprised or shocked and 30% feared incurring additional risks. While 85% of patients did not remember the trial methods (including the randomisation), most older patients (77%) not only judged that they received clear medical information but also well remembered (95%) the aim of the study and the treatment they received (67%). Finally, most older patients not only did not regret their participation (91%), but would also recommend their close relations to participate in a clinical trial (62%). CONCLUSIONS: this study demonstrates that medical scientific information can be understood and remembered by older people.

[Prevention of thrombosis during pregnancy: from recommendations to practice from 26 cases]. / Prévention des thromboses durant la grossesse: recommandations et pratique à partir de 26 dossiers.

Recommendations have recently been published regarding the prescription of low-molecular-weight heparin (LMWH) during pregnancy in women at risk of thromboembolism. To assess how well these recommendations are followed, we retrospectively recorded all pregnancy consultations in a thrombosis unit for two years. Of the 26 women included (mean age 30 +/- 4.8 years), 81% presented with a history of thromboembolism, 35% thrombophilia, and 15% a history of pregnancy termination for medical reasons. Clinical follow-up concerned 17% of the women; 8% were given aspirin, 63% LMWH at prophylactic dosages, 4% combination of aspirin and prophylactic LMWH, and 8% were on curative LMWH. Neither thromboembolic nor neonatal events were observed. One case of termination of pregnancy for medical reasons was observed at the 5th month. Although we also took into account the gravity of previous thromboembolism, our prescriptions were globally in compliance with the recommendations. This approach has still to be validated with a decision-making tree.

Meta-analysis of low molecular weight heparin in the prevention of venous thromboembolism in general surgery.

BACKGROUND: Low molecular weight heparins (LMWHs) have become routine thromboprophylaxis in general surgery. However, their actual clinical effect, its magnitude relative to that of unfractionated heparin (UFH), and the optimal dose are still debated. METHODS: A meta-analysis was performed of all available randomized trials in general surgery comparing LMWH with placebo or no treatment, or with UFH. RESULTS: Comparison versus placebo or no treatment confirmed that the significant reduction in asymptomatic deep vein thrombosis (DVT) obtained with LMWH (n = 513; relative risk (RR) 0.28 (95 per cent confidence interval 0.14-0.54)) was associated with a significant reduction in clinical pulmonary embolism (n = 5456; RR 0.25 (0.08-0.79)) and clinical venous thromboembolism (VTE) (n = 4890; RR 0.29 (0.11-0.73)), and a trend towards a reduction in overall mortality rate. Comparison versus UFH showed a trend in favour of LMWH, with a significant reduction in clinical VTE (P = 0.049), a trend also found for cancer surgery. LMWH at doses below 3400 anti-Xa units seemed to be as effective as, and safer than, UFH, while higher doses yielded slightly superior efficacy but increased haemorrhagic risk, including that of major haemorrhage. CONCLUSION: Asymptomatic DVT may be regarded as a reliable surrogate endpoint for clinical outcome in studies investigating thromboprophylaxis in general surgery. LMWH seems to be as effective and safe as UFH. Determination of the optimal dose regimen of LMWH for this indication requires further investigation.