***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Vitamin K antagonists , the current st and ard treatment for prophylaxis against stroke and systemic embolism in patients with atrial fibrillation , require regular monitoring and dose adjustment ; an unmonitored , fixed-dose anticoagulant regimen would be preferable . The aim of this r and omised , open-label non-inferiority trial was to compare the efficacy and safety of idraparinux with vitamin K antagonists . METHODS Patients with atrial fibrillation at risk for thromboembolism were r and omly assigned to receive either subcutaneous idraparinux ( 2.5 mg weekly ) or adjusted-dose vitamin K antagonists ( target of an international normalised ratio of 2 - 3 ) . Assessment of outcome was done blinded to treatment . The primary efficacy outcome was the cumulative incidence of all stroke and systemic embolism . The principal safety outcome was clinical ly relevant bleeding . Analyses were done by intention to treat ; the non-inferiority hazard ratio was set at 1.5 . This trial is registered with Clinical Trials.gov , number NCT00070655 . FINDINGS The trial was stopped after r and omisation of 4576 patients ( 2283 to receive idraparinux , 2293 to receive vitamin K antagonists ) and a mean follow-up period of 10.7 ( SD 5.4 ) months because of excess clinical ly relevant bleeding with idraparinux ( 346 cases vs 226 cases ; 19.7 vs 11.3 per 100 patient-years ; p<0.0001 ) . There were 21 instances of intracranial bleeding with idraparinux and nine with vitamin K antagonists ( 1.1 vs 0.4 per 100 patient-years ; p=0.014 ) ; elderly patients and those with renal impairment were at greater risk of such complications . There were 18 cases of thromboembolism with idraparinux and 27 cases with vitamin K antagonists ( 0.9 vs 1.3 per 100 patient-years ; hazard ratio 0.71 , 95 % CI 0.39 - 1.30 ; p=0.007 ) , satisfying the non-inferiority criterion . There were 62 deaths with idraparinux and 61 with vitamin K anatagonists ( 3.2 vs 2.9 per 100 patient-years ; p=0.49 ) . INTERPRETATION In patients with atrial fibrillation at risk for thromboembolism , long-term treatment with idraparinux was no worse than vitamin K antagonists in terms of efficacy , but caused significantly more bleeding BACKGROUND Idraparinux is an inhibitor of activated factor X ( FXa ) with a long half-life allowing once-weekly dosing . Idrabiotaparinux is a biotinylated version of idraparinux ; its activity can be reversed with avidin . OBJECTIVE To investigate the tolerability , safety and pharmacodynamics of avidin in healthy subjects and patients with deep vein thrombosis ( DVT ) receiving idrabiotaparinux .  PATIENTS AND METHODS In a placebo-controlled , r and omized , double-blind Phase I study , 41 healthy males received subcutaneous idrabiotaparinux  before being r and omized to a 30-min intravenous avidin infusion or placebo . Idrabiotaparinux plus avidin were re-administered 10 - 14 months later in eight subjects . In addition , in a prospect i ve sub study of the Phase III EQUINOX trial , 55 patients who received weekly idrabiotaparinux for 6 months were r and omized to receive either 100 mg avidin ( n = 33 ) or placebo ( n = 22 ) . The primary activity outcome was anti-FXa activity calculated immediately before and after avidin infusion . Adverse events were recorded to assess safety and tolerability . RESULTS Avidin rapidly reversed the anti-FXa activity of idrabiotaparinux , ranging from 66.1 to 90.3 % in healthy subjects and from 67 to 97 % ( mean 78 % ) in DVT patients . Avidin was well tolerated , with a similar nature and frequency of adverse events to placebo . No venous thromboembolism recurrence occurred in the 3-month post-avidin infusion . CONCLUSION A 30-min intravenous infusion of avidin 100 mg is well tolerated , safe , and offers immediate and specific reversibility both after single and repeated doses of idrabiotaparinux in healthy subjects , and in DVT patients following a 6-month treatment period BACKGROUND The efficacy and safety of anticoagulant treatment for patients with acute , symptomatic superficial-vein thrombosis in the legs , but without concomitant deep-vein thrombosis or symptomatic pulmonary embolism at presentation , have not been established . METHODS In a r and omized , double-blind trial , we assigned 3002 patients to receive either fondaparinux , administered subcutaneously at a dose of 2.5 mg once daily , or placebo for 45 days . The primary efficacy outcome was a composite of death from any cause or symptomatic pulmonary embolism , symptomatic deep-vein thrombosis , or symptomatic extension to the saphenofemoral junction or symptomatic recurrence of superficial-vein thrombosis at day 47 . The main safety outcome was major bleeding . The patients were followed until day 77 . RESULTS The primary efficacy outcome occurred in 13 of 1502 patients ( 0.9 % ) in the fondaparinux group and 88 of 1500 patients ( 5.9 % ) in the placebo group ( relative risk reduction with fondaparinux , 85 % ; 95 % confidence interval [ CI ] , 74 to 92 ; P<0.001 ) . The incidence of each component of the primary efficacy outcome was significantly reduced in the fondaparinux group as compared with the placebo group , except for the outcome of death ( 0.1 % in both groups ) . The rate of pulmonary embolism or deep-vein thrombosis was 85 % lower in the fondaparinux group than in the placebo group ( 0.2 % vs. 1.3 % ; 95 % CI , 50 to 95 ; P<0.001 ) . Similar risk reductions were observed at day 77 . A total of 88 patients would need to be treated to prevent one instance of pulmonary embolism or deep-vein thrombosis . Major bleeding occurred in one patient in each group . The incidence of serious adverse events was 0.7 % with fondaparinux and 1.1 % with placebo . CONCLUSIONS Fondaparinux at a dose of 2.5 mg once a day for 45 days was effective in the treatment of patients with acute , symptomatic superficial-vein thrombosis of the legs and did not have serious side effects . ( Funded by GlaxoSmithKline ; Clinical Trials.gov number , NCT00443053 . BACKGROUND Prophylaxis for venous thromboembolism is routinely performed for all patients undergoing bariatric surgery . However , there is disagreement regarding the optimal dosing and duration of anticoagulant therapy . Furthermore , there is little data regarding the incidence of asymptomatic deep venous thrombosis ( DVT ) in this population . Our objective was to conduct a pilot r and omized double blind study to evaluate the pharmacodynamic parameters of 2 different anticoagulation medications ( enoxaparin and fondaparinux ) administered to patients undergoing bariatric surgery . METHODS From July 2010 to August 2013 , 198 consecutive bariatric surgery patients from an academic institution were r and omized in a double blinded manner to receive either 40 mg enoxaparin twice daily or 5 mg fondaparinux sodium once daily . Antifactor Xa activity was measured on all patients in both study arms , 3 hours after the first dose ( on the day of the operation ) , immediately before the second dose ( postoperative day one ) , and 3 hours after the second dose . At the routine 2 week postoperative visit , patients underwent magnetic resonance venography ( MRV ) to detect DVT . The primary outcome was attainment of therapeutic antifactor Xa levels . The secondary outcome was DVT , as detected by MRV . Safety outcomes were perioperative bleeding , perioperative complications , and death . RESULTS Of 198 patients r and omized , 177 underwent MRV and 137 had interpretable antifactor Xa levels . Nearly half of the patients ( 47.4 % ) did not attain target prophylactic antifactor Xa levels . Adequate antifactor Xa levels were more common with fondaparinux ( 74.2 % ) than with enoxaparin ( 32.4 % ) . Antifactor Xa levels were also associated with preoperative D-dimer level . 4 of the 175 patients who underwent MRV developed DVT , 2 in each arm of the study . No major adverse events occurred in either arm . CONCLUSION Fondaparinux was much more likely to produce target prophylactic antifactor Xa levels than enoxaparin . Both regimens appear to be equally effective at reducing the risk of DVT . Further prospect i ve studies are needed to determine the optimal DVT prophylaxis regimen in the bariatric surgical population 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 r and omized , double-blind , placebo-controlled superiority trial . Patients aged at least 40 years undergoing abdominal surgery were r and omized 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 r and omized , 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 OBJECTIVE To explore the efficacy and safety of fondaparinux combined with tirofiban in patients with high risk unstable angina ( UA ) undergoing complex percutaneous coronary intervention ( PCI ) . METHODS A total of 389 patients were enrolled and r and omized into two groups receiving either fondaparinux with tirofiban or enoxaparin with tirofiban .  Bleeding , thrombosis and main adverse cardiovascular events ( MACE ) were compared between the two groups during hospitalization , at week 2 and week 4 after discharge . RESULTS No severe bleeding was observed during hospitalization in the both groups , while lower rate of mild and minor bleeding was shown in the fondaparinux group ( 0 vs 1.5 % and 18.2 % vs 34.5 % , P = 0.04 and P < 0.001 respectively ) . No difference was found between the two groups in the rate of MACE during hospitalization , at week 2 and week 4 weeks after discharge . The rates of death , recurrent myocardial infa rct ion , refractory myocardial ischemia and target vessel revascularization were 0.5 % vs 1.0 % , 0.5 % vs 1.0 % , 1.6 % vs 1.0 % and 2.1 % vs 1.5 % during hospitalization ; 0 vs 0 , 1.0 % vs 0.5 % , 1.0 % vs 1.5 % , 0.5 % vs 1.0 % at week 2 after discharge ; 0.5 % vs 0.5 % , 0.5 % vs 0.5 % , 2.6 % vs 2.0 % , 0 vs 0.5 % at week 4 after discharge ( all P values>0.05 
    Output:
    
Results showed no difference in total VTE and total DVT between fondaparinux and mechanical thromboprophylaxis .
Moderate to high quality evidence shows that fondaparinux is effective for short-term prevention of VTE when compared with placebo .
It can reduce total VTE , DVT , total PE and symptomatic VTE , and does not demonstrate a reduction in deaths compared with placebo .
Low to moderate quality evidence shows that fondaparinux is more effective for short-term VTE prevention when compared with LMWH .
It can reduce total VTE and total DVT and does not demonstrate a reduction in deaths when compared with LMWH .
However , at the same time , moderate to high quality evidence shows that fondaparinux increases major bleeding when compared with placebo and LMWH .