Fondaparinux combined with intermittent pneumatic compression vs. intermittent pneumatic compression alone for prevention of venous thromboembolism after abdominal surgery: a randomized, double-blind comparison

BACKGROUND: The benefit of combined mechanical and pharmacologic methods for venous thromboembolism prevention after abdominal surgery has not been clearly established. OBJECTIVES: To compare the efficacy and safety of fondaparinux in conjunction with intermittent pneumatic compression vs. intermittent pneumatic compression alone in this context. PATIENTS AND METHODS: This was a randomized, double-blind, placebo-controlled superiority trial. Patients aged at least 40 years undergoing abdominal surgery were randomized to receive either fondaparinux 2.5 mg or placebo s.c. for 5-9 days, starting 6-8 h postoperatively. All patients received intermittent pneumatic compression. The primary efficacy outcome was venous thromboembolism up to day 10. The main safety outcomes were major bleeding and all-cause mortality. Follow-up lasted 32 days. RESULTS: Of the 1309 patients randomized, 842 (64.3%) were evaluable for efficacy. The venous thromboembolism rate was 1.7% (7/424) in the fondaparinux-treated patients and 5.3% (22/418) in the placebo-treated patients (odds ratio reduction 69.8%; 95% confidence interval 27.9-87.3; P = 0.004). Fondaparinux significantly reduced the proximal deep vein thrombosis rate from 1.7% (7/417) to 0.2% (1/424; P = 0.037). Major bleeds occurred in 1.6% (10/635) and 0.2% (1/650) of fondaparinux-treated and placebo-treated patients, respectively (P = 0.006), none being fatal or involving a critical organ. By day 32, eight patients (1.3%) receiving fondaparinux and five (0.8%) receiving placebo had died. CONCLUSIONS: In patients undergoing abdominal surgery and receiving intermittent pneumatic compression, fondaparinux 2.5 mg reduced the venous thromboembolism rate by 69.8% as compared to pneumatic compression alone, with a low bleeding risk as compared to placebo.     

Comparison of local International Sensitivity Index calibration and ''Direct INR'' methods in correction of locally reported International Normalized Ratios: an international study

BACKGROUND: It is no longer feasible to check local International Normalized Ratios (INR) by the World Health Organization International Sensitivity Index (ISI) calibrations because the necessary manual prothrombin time technique required has generally been discarded. OBJECTIVES: An international collaborative study at 77 centers has compared local INR correction using the two alternative methods recommended in the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis guidelines: local ISI calibration and 'Direct INR'. METHODS: Success of INR correction by local ISI calibration and with Direct INR was assessed with a set of 27 certified lyophilized plasmas (20 from patients on warfarin and seven from normals). RESULTS: At 49 centers using human thromboplastins, 3.0% initial average local INR deviation from certified INR was reduced by local ISI calibration to 0.7%, and at 25 centers using rabbit reagents, from 15.9% to 7.5%. With a minority of commercial thromboplastins, mainly 'combined' rabbit reagents, INR correction was not achieved by local ISI calibration. However, when rabbit combined reagents were excluded the overall mean INR deviation after correction was reduced further to 3.9%. In contrast, with Direct INR, mean deviation using human thromboplastins increased from 3.0% to 6.6%, but there was some reduction with rabbit reagents from 15.9% to 10% (12.3% with combined reagents excluded). CONCLUSIONS: Local ISI calibration gave INR correction for the majority of PT systems but failed at the small number using combined rabbit reagents suggesting a need for a combined reference thromboplastin. Direct INR correction was disappointing but better than local ISI calibration with combined rabbit reagents. Interlaboratory variability was improved by both procedures with human reagents only.     

The prothrombin time/international normalized ratio (PT/INR) Line: derivation of local INR with commercial thromboplastins and coagulometers – two independent studies

Summary. Background: The WHO scheme for prothrombin time (PT) standardization has been limited in application, because of its difficulties in implementation, particularly the need for mandatory manual PT testing and for local provision of thromboplastin international reference preparations (IRP). Methods: The value of a new simpler procedure to derive international normalized ratio (INR), the PT/INR Line, based on only five European Concerted Action on Anticoagulation (ECAA) calibrant plasmas certified by experienced centres has been assessed in two independent exercises using a range of commercial thromboplastins and coagulometers. INRs were compared with manual certified values with thromboplastin IRP from expert centres and in the second study also with INRs from local ISI calibrations. Results: In the first study with the PT/INR Line, 8.7% deviation from certified INRs was reduced to 1.1% with human reagents, and from 7.0% to 2.6% with rabbit reagents. In the second study, deviation was reduced from 11.2% to 0.4% with human reagents by both local ISI calibration and the PT/INR Line. With rabbit reagents, 10.4% deviation was reduced to 1.1% with both procedures; 4.9% deviation was reduced to 0.5% with bovine/combined reagents with local ISI calibrations and to 2.9% with the PT/INR Line. Mean INR dispersion was reduced with all thromboplastins and automated systems using the PT/INR Line. Conclusions: The procedure using the PT/INR Line provides reliable INR derivation without the need for WHO ISI calibration across the range of locally used commercial thromboplastins and automated PT systems included in two independent international studies.     

Value assignment of the WHO 2nd International Standard von Willebrand factor,concentrate (09/182)

To cite this article: Hubbard AR, Hamill M, Beeharry M, Bevan SA, Heath AB, on behalf of the SSC sub‐committee on von Willebrand factor of ISTH. Value assignment of the WHO 2nd International Standard von Willebrand factor, concentrate (09/182). J Thromb Haemost 2011; 9 : 1638–40.DOI: 10.1111/j.1538‐7836.2011.04365.x .     

Outpatient treatment in patients with acute pulmonary embolism: the Hestia Study

Summary. Background: Traditionally, patients with pulmonary embolism (PE) are initially treated in the hospital with low molecular weight heparin (LMWH). The results of a few small non‐randomized studies suggest that, in selected patients with proven PE, outpatient treatment is potentially feasible and safe. Objective: To evaluate the efficacy and safety of outpatient treatment according to predefined criteria in patients with acute PE. Patients and Methods: A prospective cohort study of patients with objectively proven acute PE was conducted in 12 hospitals in The Netherlands between 2008 and 2010. Patients with acute PE were triaged with the predefined criteria for eligibility for outpatient treatment, with LMWH (nadroparin) followed by vitamin K antagonists. All patients eligible for outpatient treatment were sent home either immediately or within 24 h after PE was objectively diagnosed. Outpatient treatment was evaluated with respect to recurrent venous thromboembolism (VTE), including PE or deep vein thrombosis (DVT), major hemorrhage and total mortality during 3 months of follow‐up. Results: Of 297 included patients, who all completed the follow‐up, six (2.0%; 95% confidence interval [CI] 0.8–4.3) had recurrent VTE (five PE [1.7%] and one DVT [0.3%]). Three patients (1.0%, 95% CI 0.2–2.9) died during the 3 months of follow‐up, none of fatal PE. Two patients had a major bleeding event, one of which was fatal intracranial bleeding (0.7%, 95% CI 0.08–2.4). Conclusion: Patients with PE selected for outpatient treatment with predefined criteria can be treated with anticoagulants on an outpatient basis. (Dutch Trial Register No 1319; http://www.trialregister.nl/trialreg/index.asp ).     

Low‐molecular‐weight heparin added to aspirin in the prevention of recurrent early‐onset pre‐eclampsia in women with inheritable thrombophilia: the FRUIT‐RCT

Summary. Background: Early‐onset hypertensive disorders (HD) of pregnancy and small‐for‐gestational age infants (SGA) are associated with placental vascular thrombosis, these often recur and are also associated with inheritable thrombophilia. Aspirin reduces the recurrence risk. Objectives: Adding low‐molecular‐weight heparin (LMWH) to aspirin at < 12 weeks gestation reduces the recurrence of HD in women with previous early‐onset HD (pre‐eclampsia, hemolysis, elevated liver enzymes and low platelets [HELLP] syndrome and eclampsia) and/or SGA, in the context of inheritable thrombophilia without antiphospholipid antibodies. Patients/methods: In a multicenter randomized control trial (RCT), 139 women included were < 12 weeks gestation. Inclusion criteria: previous delivery < 34 weeks gestation with HD and/or SGA; inheritable thrombophilia (protein C deficiency, protein S deficiency, activated protein C resistance, factor V Leiden heterozygosity and prothrombin gene G20210A mutation heterozygosity); and no antiphospholipid antibodies detected. Intervention: either daily LMWH (dalteparin, 5000 IU weight‐adjusted dosage) with aspirin 80 mg or aspirin 80 mg alone. Main outcome measures: Primary outcomes: recurrent HD onset (i) < 34 weeks gestation and (ii) irrespective of gestational age. Secondary outcomes: recurrent SGA, preterm birth, maternal/neonatal hospitalization, spontaneous abortion and individual HD. Analysis by intention‐to‐treat. Results: Low‐molecular‐weight heparin with aspirin reduced recurrent HD onset < 34 weeks gestation (risk difference [RD] 8.7%: confidence interval [CI] of RD 1.9–15.5%; P = 0.012; number needed to treat [NNT] 12). Recurrent HD irrespective of gestational age was not different between the arms. No women withdrew as a result of adverse effects. Trial Registration: http://www.isrctn.org ) (isrctn87325378). Conclusions: Adding LMWH to aspirin at < 12 weeks gestation reduces recurrent HD onset < 34 weeks gestation in women with inheritable thrombophilia and prior delivery for HD/SGA <34 weeks. However, close monitoring of the mother and fetus remains important throughout pregnancy.