***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 
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    Input: BACKGROUND Warfarin , which requires coagulation monitoring , is associated with relatively high rates of thromboembolism despite providing adequate prophylaxis . This study compared an oral direct thrombin inhibitor , ximelagatran , with warfarin in order to evaluate the safety and efficacy of the medication for the prevention of venous thromboembolism in patients undergoing total knee arthroplasty . METHODS Following surgery , patients were r and omly assigned to fixed-dose oral ximelagatran ( 36 mg twice daily ) or warfarin ( target international normalized ratio , 2.5 ) , both administered for seven to twelve days in a double-blind , double-dummy design . Warfarin was initiated on the evening of the day of surgery , and ximelagatran , on the morning after surgery . The primary efficacy end point was the incidence of asymptomatic deep-vein thrombosis determined by bilateral venography , objective ly confirmed symptomatic deep-vein thrombosis or pulmonary embolism , and death from all causes during treatment . RESULTS Adequate venograms or confirmed symptomatic events ( efficacy population ) were obtained for 1949 patients .  Venous thromboembolism and death from all causes occurred in 22.5 % ( 221 ) of 982 ximelagatran-treated patients and in 31.9 % ( 308 ) of 967 warfarin-treated patients ( p < 0.001 ) . Proximal deep-vein thrombosis and pulmonary embolism were observed in 3.1 % ( thirty ) and 0.2 % , respectively , of the patients in the ximelagatran group and in 3.4 % ( thirty-three ) and 0.4 % , respectively , of the patients in the warfarin group . The six deaths from all causes included 0.3 % ( four ) of the ximelagatran-treated patients and 0.2 % ( two ) of the warfarin-treated patients . Major bleeding was noted in 1 % ( twelve ) of the ximelagatran-treated patients and in 0.4 % ( five ) of the warfarin-treated patients ( p = 0.09 ) . CONCLUSIONS Oral ximelagatran ( 36 mg twice daily ) , administered without coagulation monitoring or dose adjustment and started the day after total knee arthroplasty , demonstrates superior efficacy compared with warfarin prophylaxis , with no wound complications and no significant difference with respect to bleeding events , although the rate of major bleeding events was greater with ximelagatran than with warfarin . LEVEL OF EVIDENCE Therapeutic Level BACKGROUND Current treatment regimens that are design ed to prevent deep venous thrombosis in patients undergoing orthopaedic procedures rely predominantly on drug prophylaxis alone . The purpose of this r and omized clinical study was to evaluate the effectiveness of a mechanical adjunct to chemoprophylaxis that involves intermittent compression of the legs . METHODS During a twenty-two month period , 1803 patients undergoing a variety of orthopaedic procedures were prospect ively r and omized to receive either chemoprophylaxis alone or a combination of chemoprophylaxis and mechanical prophylaxis .  Nine hundred and two patients were managed with low-molecular-weight heparin alone , and 901 were managed with low-molecular-weight heparin and intermittent pneumatic compression of the calves for varying time periods . Twenty-four percent of the patients underwent total hip or knee joint replacement . Screening for deep venous thrombosis was performed on the day of discharge with duplex-color-coded ultrasound . RESULTS In the chemoprophylaxis-only group , fifteen patients ( 1.7 % ) were diagnosed with a deep venous thrombosis ; three thromboses were symptomatic . In the chemoprophylaxis plus intermittent pneumatic compression group , four patients ( 0.4 % ) were diagnosed with deep venous thrombosis ; one thrombosis was symptomatic . The difference between the groups with regard to the prevalence of deep venous thrombosis was significant ( p = 0.007 ) . In the chemoprophylaxis plus intermittent pneumatic compression group , no deep venous thromboses were found in patients who received more than six hours of intermittent pneumatic compression daily . CONCLUSIONS Venous thrombosis prophylaxis with low-molecular-weight heparin augmented with a device that delivers rapid-inflation intermittent pneumatic compression to the calves was found to be significantly more effective for preventing deep venous thrombosis when compared with a treatment regimen that involved low-molecular-weight heparin alone OBJECTIVE To evaluate the efficacy and safety of the low molecular weight heparin as prophylaxis against thromboembolism following total knee replacement surgery . METHODS Post-operative bilateral lower extremity colour duplex scan was performed on 55 patients subjected to total knew arthroplasty . The scan was performed 7 days after surgery for detection of DVT . All patients were given Enoxaparin 40 mg subcutaneous daily for 2 weeks as prophylaxis against DVT . RESULTS Two patients were diagnosed as DVT by color duplex scanning and both were distal but only one was asymptomatic . Another patient developed pulmonary embolism and died subsequently . The major and minor wound problems were seen in two and six patients respectively ; nearly all complications were seen in obese patients . CONCLUSION DVT is not a nonexistent entity in our population . Low molecular weight heparins are safe drugs but apparently the bleeding complications are more as compared to Western literature . Larger case control studies are required to determine the true efficacy and safety of LMWH BACKGROUND The incidence of postsurgical venous thromboembolism is thought to be low in Asian ethnic population s. OBJECTIVE We studied the incidence of deep-vein thrombosis ( DVT ) in Asian patients undergoing major orthopedic surgery of the lower limbs . PATIENTS / METHODS We performed a prospect i ve epidemiological study in 19 centers across Asia ( China , Indonesia , South Korea , Malaysia , Philippines , Taiwan , and Thail and ) in patients undergoing elective total hip replacement ( THR ) , total knee replacement ( TKR ) or hip fracture surgery ( HFS ) without pharmacological thromboprophylaxis .  The primary endpoint was the rate of DVT of the lower limbs documented objective ly with bilateral ascending venography performed 6 - 10 days after surgery using a st and ardized technique and evaluated by a central adjudication committee unaware of local interpretation . RESULTS Overall , of 837 Asian patients screened for this survey , 407 ( 48.6 % , aged 20 - 99 years ) undergoing THR ( n = 175 ) , TKR ( n = 136 ) or HFS ( n = 96 ) were recruited in 19 centers . DVT was diagnosed in 121 of 295 evaluable patients [ 41.0 % , ( 95 % confidence interval ( CI ) : 35.4 - 46.7 ) ] . Proximal DVT was found in 30 patients [ 10.2 % ( 7.0 - 14.2 ) ] . Total DVT and proximal DVT rates were highest in TKR patients ( 58.1 % and 17.1 % , respectively ) , followed by HFS patients ( 42.0 % and 7.2 % , respectively ) , then THR patients ( 25.6 % and 5.8 % , respectively ) . DVT was more frequent in female patients aged at least 65 years . Pulmonary embolism was clinical ly suspected in 10 of 407 patients ( 2.5 % ) and objective ly confirmed in two ( 0.5 % ) . CONCLUSIONS The rate of venographic thrombosis in the absence of thromboprophylaxis after major joint surgery in Asian patients is similar to that previously reported in patients in Western countries Introduction : The incidence of venous thromboembolism ( VTE ) in Western population s undergoing major orthopaedic surgery without any thromboprophylaxis has been reported to range from 32 % to 88 % . There is however limited information on incidence of VTE in Indian patients and most of the Indian patients undergoing these surgeries do not receive any form of prophylaxis regardless of their risk profile . Methods : A prospect i ve study was performed on 147 patients undergoing major orthopaedic surgery for total knee replacement ( TKR ) , total hip replacement ( THR ) , and proximal femur fracture fixation ( PFF ) without any prophylaxis .  These patients were profiled for presence of the known risk factors responsible for development of VTE . A duplex ultrasound on both lower limbs was done 6 to 10 days after surgery . Twenty three patients underwent THR , 22 patients underwent TKR , and 102 underwent surgery for PFF . The patients were assessed clinical ly for any signs of deep venous thrombosis ( DVT ) and pulmonary embolism ( PE ) . A helical CT scan was done in case of suspicion of PE and a duplex ultrasound was done in case of clinical suspicion of DVT irrespective of the stage of study . Results : The overall incidence of VTE was 6.12 % and that of PE was 0.6 % . The risk factors that were found to be significantly responsible for development of VTE ( p < 0.05 ) were : immobility greater than 72 hours , malignancy , obesity , surgery lasting more than two hours . Conclusion : The study reconfirms the belief that DVT has a lower incidence in Indian patients as compared with other ethnic groups BACKGROUND In view of recent substantial changes in the management of orthopedic surgery patients , a study was performed in order to up date data on the epidemiology of venous thromboembolism ( VTE ) in patients undergoing lower limb arthroplasty according to contemporary practise . METHODS We performed a prospect i ve observational study of a cohort of consecutive patients hospitalized for total hip or knee replacement in June 2003 . The primary study outcome was the incidence of symptomatic VTE at 3 months . All events were adjudicated by an independent critical event committee . RESULTS Data from 1080 patients ( mean age 68.0 years ) were available ; 63.2 % were undergoing total hip replacement and 36.8 % total knee replacement . Pharmacological thromboprophylaxis was administered for a mean time of 36 days . Injectable antithrombotics were used in more than 99 % of patients , irrespective of the type of surgery . The incidence of the primary study outcome was 1.8 % ( 20 events ; 95 % CI : 1.0 - 2.6 % ) . The incidences were 1.3 % and 2.8 % in hip and knee surgery patients , respectively . There were two pulmonary embolisms , both in knee surgery patients ; neither was fatal . Thirty-five per cent of VTEs occurred after hospital discharge . An age of at least 75 years and the absence of ambulation before hospital discharge were the only significant ( P < 0.05 ) predictors of VTE . The rate of clinical ly significant bleeding was 1.0 % and the rate of death was 0.9 % . CONCLUSIONS The incidence of symptomatic VTE after lower limb arthroplasty is low , even if there is still a need to improve thromboprophylaxis , notably in patients undergoing knee arthroplasty BACKGROUND Heparins and warfarin are currently used as venous thromboembolism ( VTE ) prophylaxis in surgery . Inhibition of factor ( F ) Xa provides a specific mechanism of anticoagulation and the potential for an improved benefit-risk profile . OBJECTIVES To evaluate the safety and efficacy of apixaban , a potent , direct , oral inhibitor of FXa , in patients following total knee replacement ( TKR ) , and to investigate dose-response relationships . PATIENTS / METHODS A total of 1238 patients were r and omized to one of six double-blind apixaban doses [ 5 , 10 or 20 mg day(-1 ) administered as a single ( q.d . ) or a twice-daily divided dose ( b.i.d . ) ] , enoxaparin ( 30 mg b.i.d . ) or open-label warfarin ( titrated to an International Normalized Ratio of 1.8 - 3.0 ) . Treatment lasted 10 - 14 days , commencing 12 - 24 h after surgery with apixaban or enoxaparin , and on the evening of surgery with warfarin . The primary efficacy outcome was a composite of VTE ( m and atory venography ) and all-cause mortality during treatment . The primary safety outcome was major bleeding . RESULTS A total of 1217 patients were eligible for safety and 856 patients for efficacy analysis . All apixaban groups had lower primary efficacy event rates than either comparator . The primary outcome rate decreased with increasing apixaban dose ( P = 0.09 with q.d./b.i.d . regimens combined , P = 0.19 for q.d . and P = 0.13 for b.i.d . dosing).A significant dose-related increase in the incidence of total adjudicated bleeding events was noted in the q.d . ( P = 0.01 ) and b.i.d . ( P = 0.02 ) apixaban groups ; there was no difference between q.d . and b.i.d . regimens . CONCLUSIONS Apixaban in doses of 2.5 mg b.i.d . or 5 mg q 
    Output:
    
CONCLUSIONS Most studies on thromboprophylaxis after total joint arthroplasty are sponsored by industry .
Moreover , the qualitative conclusions in those studies are favorable to the use of the sponsored prophylactic agent