human
***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 AND PURPOSE Although the efficacy of anticoagulant therapy for primary prevention of stroke in patients with nonvalvular atrial fibrillation ( NVAF ) has been established , efficacy of antiplatelet therapy for low-risk patients is disputable in Japanese patients because of the frequent hemorrhagic complications . We examined the efficacy and safety of aspirin therapy in Japanese patients with NVAF in a prospect i ve r and omized multicenter trial . METHODS Patients with NVAF were r and omized to an aspirin group ( aspirin at 150 to 200 mg per day ) or a control group without antiplatelet or anticoagulant therapy . Primary end points included cardiovascular death , symptomatic brain infa rct ion , or transient ischemic attack . RESULTS A total of 426 patients were r and omized to aspirin group and 445 to no treatment . The trial was stopped earlier because there were 27 primary end point events ( 3.1 % per year ; 95 % CI , 2.1 % to 4.6 % per year ) in the aspirin group versus 23 ( 2.4 % per year ; 95 % CI , 1.5 % to 3.5 % per year ) in the control group , suggesting a low possibility of superiority of the aspirin treatment for prevention of the primary end point . In addition , treatment with aspirin caused a marginally increased risk of major bleeding ( 7 patients ; 1.6 % ) compared with the control group ( 2 patients ; 0.4 % ; Fisher exact test P=0.101 ) . CONCLUSIONS For prevention of stroke in patients with NVAF , aspirin at 150 to 200 mg per day does not seem to be either effective or safe . Further prospect i ve studies are needed to determine the best preventive therapy for cerebrovascular events in Japanese patients with NVAF BACKGROUND To test the use of three lead monitoring as a screening tool for  atrial fibrillation ( AF )  in general practice . AF is responsible for up to a quarter of all strokes and is often asymptomatic until a stroke occurs . METHODS 26 r and omly selected general practice s identified 80 r and omly selected patients aged 70 or older from their data base and excluded those known to have AF , those with clinical issues or who had not attended for three years . Up to 40 eligible patients / practice were invited to attend for screening . A 2min three-lead ECG was recorded and collected central ly for expert cardiology assessment . Risk factor data was gathered . OUTCOMES ( i ) point prevalence of AF , ( ii ) proportion of ECG tracings which were adequate for interpretation , ( iii ) uptake rate by patients and ( iv ) acceptability of the screening process to patients and staff ( reported separately ) . RESULTS Of 1447 current patients , 1003 were eligible for inclusion , 639 ( 64 % ) agreed to take part in screening and 566 ( 56 % ) completed screening . The point prevalence rate for AF was 10.3%-2.1 % new cases ( 12 of 566 who were screened ) and 9.5 % existing cases ( 137 of 1447 eligible patients ) . Only four of 570 ( 0.7 % ) screening visits did not record a usable ECG and 11 ( 2.6 % ) three lead ECGs required a clarifying 12 lead ECG . CONCLUSIONS Three lead screening for AF is feasible , effective and offers an alternative to pulse taking or 12 lead ECGs . The availability of this technology may facilitate more effective screening , leading to reduced stroke incidence Objectives To assess whether screening improves the detection of atrial fibrillation  ( cluster r and omisation ) and to compare systematic and opportunistic screening . Design Multicentred cluster r and omised controlled trial , with subsidiary trial embedded within the intervention arm . Setting 50 primary care centres in Engl and , with further individual r and omisation of patients in the intervention practice s. Participants 14 802 patients aged 65 or over in 25 intervention and 25 control practice s. Interventions Patients in intervention practice s were r and omly allocated to systematic screening ( invitation for electrocardiography ) or opportunistic screening ( pulse taking and invitation for electrocardiography if the pulse was irregular ) . Screening took place over 12 months in each practice from October 2001 to February 2003 . No active screening took place in control practice s. Main outcome measure Newly identified atrial fibrillation . Results The detection rate of new cases of atrial fibrillation was 1.63 % a year in the intervention practice s and 1.04 % in control practice s ( difference 0.59 % , 95 % confidence interval 0.20 % to 0.98 % ) . Systematic and opportunistic screening detected similar numbers of new cases ( 1.62 % v 1.64 % , difference 0.02 % , −0.5 % to 0.5 % ) . Conclusion Active screening for atrial fibrillation detects additional cases over current practice . The preferred method of screening in patients aged 65 or over in primary care is opportunistic pulse taking with follow-up electrocardiography . Trial registration Current Controlled Trials IS RCT N19633732 INTRODUCTION AND OBJECTIVES Atrial fibrillation constitutes a serious public health problem because it can lead to complications . Thus , the management of this arrhythmia must include not only its treatment , but antithrombotic therapy as well . The main goal is to determine the proportion of cases of undiagnosed atrial fibrillation and the proportion of patients not being treated with oral anticoagulants . METHODS A multicenter , population -based , retrospective , cross-sectional , observational study . In all , 1043 participants over 60 years of age were r and omly selected to undergo an electrocardiogram in a prearranged appointment .  Demographic data , CHA2DS2-VASc and HAS-BLED scores , international normalized ratio results , and reasons for not receiving oral anticoagulant therapy  were recorded . RESULTS The overall prevalence of atrial fibrillation was 10.9 % ( 95 % confidence interval , 9.1%-12.8 % ) , 20.1 % of which had not been diagnosed previously . In the group with known atrial fibrillation , 23.5 % of those with CHA2DS2-VASc≥2 were not receiving oral anticoagulant therapy , and 47.9 % had a HAS-BLED score≥3 . The odds ratio for not being treated with oral anticoagulation  was 2.04 ( 95 % confidence interval , 1.11 - 3.77 ) for women , 1.10 ( 95 % confidence interval , 1.05 - 1.15 ) for more advanced age at diagnosis , and 8.61 ( 95 % confidence interval 2.38 - 31.0 ) for a CHA2DS2-VASc score<2 . Cognitive impairment ( 15.2 % ) was the main reason for not receiving oral anticoagulant therapy . CONCLUSIONS The prevalence of previously undiagnosed atrial fibrillation in individuals over 60 years of age is 20.1 % , and 23.5 % of those who have been diagnosed receive no treatment with oral anticoagulants AIM Atrial fibrillation ( AF ) is associated with high morbidity and mortality . Early diagnosis is likely to improve therapy and prognosis . The study objective was to evaluate the usefulness of a programme for early diagnosis of AF in patients from an urban primary care centre . METHODS AND RESULTS Participants were recruited from a r and omized sample of patients not diagnosed with AF but having relevant risk factors : age ≥ 65 years , ischaemic and /or valvular heart disease , congestive heart failure , hypertension , and /or diabetes . Patients were r and omly assigned to the intervention group ( IG ) or control group ( CG ) . The intervention included ( i ) initial visit with clinical history , electrocardiogram , and instruction about pulse palpation and warning signs and ( ii ) electrocardiogram every 6 months during a 2-year follow-up . The main endpoint of the study was the proportion of new cases diagnosed at 6 months . Secondary endpoints were number of new AF diagnoses and complications associated with the arrhythmia in both groups . A total of 928 patients were included ( 463 IG and 465 CG ) . At 6 months , AF was diagnosed in 8 IG patients and 1 CG patient ( 1.7 vs. 0.2 % , respectively , P = 0.018 ) . After 2 years of follow-up , 11 IG patients and 6 CG patients had newly diagnosed AF ( 2.5 vs. 1.3 % , respectively , P = 0.132 ) . Time to first diagnosis of AF was shorter in IG patients [ median ( inter-quartile range ) : 7 ( 192 ) days vs. 227 ( 188.5 ) days in CG , P = 0.029 ] . CONCLUSION The simple screening proposed could be useful for the early detection of AF in primary care BACKGROUND R and omized trials have shown a beneficial effect of anticoagulation with warfarin to prevent stroke in atrial fibrillation . It is not known whether the same effect will be obtained in actual practice . The authors conducted a prospect i ve observational study to evaluate the effect of preventive anticoagulation in patients with atrial fibrillation in 2 practice setting s in Montreal . METHODS Of the 1725 out patients screened between October 1990 and September 1993 at a community hospital and a university-affiliated hospital , 221 with documented atrial fibrillation were enrolled and followed up for a mean of 27 months . Most ( 75 % ) of the patients excluded did not meet the inclusion criteria ( because of , for example , an artificial heart valve , mitral stenosis , cardiac transplantation or transient atrial fibrillation ) ; the remainder had not completed enrollment before the end of the study . Following the baseline visit , patients were interviewed by telephone every 6 months , and reported events were confirmed through review of the patients ' charts . Hazards for stroke and for stroke and transient ischemic attack ( TIA ) combined were calculated for each of 4 treatment groups : ASA , warfarin , blended treatment and no treatment , based on the type of anticoagulation therapy patients received during the entire observation period . The blended-treatment group consisted of patients who started on one active therapy and switched to the other or who switched treatments more than once . Corresponding rate ratios ( RRs ) and 95 % confidence intervals ( CIs ) were calculated with reference to the no-treatment group . Cox proportional hazards analysis was used to adjust for differences in patient characteristics . The rates of bleeding episodes were also analysed . RESULTS On average , the study patients were older ( 71.6 [ st and ard deviation 9.3 ] years ) and had a higher prevalence of underlying heart disease ( 52.0 % ) than those in the r and omized trials . Nineteen patients had a first stroke : 4 in the ASA group , 4 in the warfarin group , 4 in the blended-treatment group and 7 in the no-treatment group , for rates of 5.2 , 1.8 , 5.3 and 5.9 per 100 person-years , respectively . Only warfarin was associated with a significantly lower risk of stroke compared with no anticoagulant therapy ( RR 0.31 , 95 % CI 0.09 - 1.00 ) . A similar protective effect of warfarin was found for stroke and TIA combined ( 2.3 v. 6.7 per 100 person-years ; RR 0.34 , 95 % CI 0.12 - 0.99 ) ; the effect of ASA and blended treatment was not significantly different from no treatment . The rate per 100 person-years of any bleeding was not significantly higher for any treatment group ( ASA 2.5 , warfarin 3.4 and blended treatment 3.5 ) compared with the no-treatment group ( 1.9 ) . Patients receiving warfarin had a significantly greater risk of any bleeding event than patients not receiving anticoagulant therapy ( RR 1.79 , 95 % CI 1.07 - 3.00 ) . INTERPRETATION The relative effect of anticoagulant therapy with warfarin in preventing stroke in these practice setting s was equivalent to that in the r and omized trials , although these patients were older and sicker . This preventive treatment is likely to confer additional benefit as it is more widely prescribed Background and Purpose — Stroke risk increases with age in patients who have nonvalvular atrial fibrillation . It is uncertain whether the efficacy of stroke prevention therapies in atrial fibrillation changes as patients age . The objective of this study was to determine the effect of age on the relative efficacy of oral anticoagulants ( OAC ) and antiplatelet ( AP ) therapy ( including acetylsalicylic acid and triflusal ) on ischemic stroke , serious bleeding , and vascular events in patients with atrial fibrillation . Methods — This is an analysis of the Atrial Fibrillation Investigators data base , which contains patient level- data from r and omized trials of stroke prevention in atrial fibrillation . We used Cox regression models with age as a continuous variable that controlled for sex , year of r and omization , and history of cerebrovascular disease , diabetes , hypertension , and congestive heart failure . Outcomes included ischemic stroke , serious bleeding ( intracranial hemorrhage or systemic bleeding requiring hospitalization , transfusion , or surgery ) , and cardiovascular events ( ischemic stroke , myocardial infa r 
    Output:
    
agent
Conclusions and Relevance Although screening with ECG can detect previously unknown cases of atrial fibrillation , it has not been shown to detect more cases than screening focused on pulse palpation .
Treatments for atrial fibrillation reduce the risk of stroke and all-cause mortality and increase the risk of bleeding , but trials have not assessed whether treatment of screen-detected asymptomatic older adults results in better health outcomes than treatment after detection by usual care or after symptoms develop
***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 AND PURPOSE Although the efficacy of anticoagulant therapy for primary prevention of stroke in patients with nonvalvular atrial fibrillation ( NVAF ) has been established , efficacy of antiplatelet therapy for low-risk patients is disputable in Japanese patients because of the frequent hemorrhagic complications . We examined the efficacy and safety of aspirin therapy in Japanese patients with NVAF in a prospect i ve r and omized multicenter trial . METHODS Patients with NVAF were r and omized to an aspirin group ( aspirin at 150 to 200 mg per day ) or a control group without antiplatelet or anticoagulant therapy . Primary end points included cardiovascular death , symptomatic brain infa rct ion , or transient ischemic attack . RESULTS A total of 426 patients were r and omized to aspirin group and 445 to no treatment . The trial was stopped earlier because there were 27 primary end point events ( 3.1 % per year ; 95 % CI , 2.1 % to 4.6 % per year ) in the aspirin group versus 23 ( 2.4 % per year ; 95 % CI , 1.5 % to 3.5 % per year ) in the control group , suggesting a low possibility of superiority of the aspirin treatment for prevention of the primary end point . In addition , treatment with aspirin caused a marginally increased risk of major bleeding ( 7 patients ; 1.6 % ) compared with the control group ( 2 patients ; 0.4 % ; Fisher exact test P=0.101 ) . CONCLUSIONS For prevention of stroke in patients with NVAF , aspirin at 150 to 200 mg per day does not seem to be either effective or safe . Further prospect i ve studies are needed to determine the best preventive therapy for cerebrovascular events in Japanese patients with NVAF BACKGROUND To test the use of three lead monitoring as a screening tool for  atrial fibrillation ( AF )  in general practice . AF is responsible for up to a quarter of all strokes and is often asymptomatic until a stroke occurs . METHODS 26 r and omly selected general practice s identified 80 r and omly selected patients aged 70 or older from their data base and excluded those known to have AF , those with clinical issues or who had not attended for three years . Up to 40 eligible patients / practice were invited to attend for screening . A 2min three-lead ECG was recorded and collected central ly for expert cardiology assessment . Risk factor data was gathered . OUTCOMES ( i ) point prevalence of AF , ( ii ) proportion of ECG tracings which were adequate for interpretation , ( iii ) uptake rate by patients and ( iv ) acceptability of the screening process to patients and staff ( reported separately ) . RESULTS Of 1447 current patients , 1003 were eligible for inclusion , 639 ( 64 % ) agreed to take part in screening and 566 ( 56 % ) completed screening . The point prevalence rate for AF was 10.3%-2.1 % new cases ( 12 of 566 who were screened ) and 9.5 % existing cases ( 137 of 1447 eligible patients ) . Only four of 570 ( 0.7 % ) screening visits did not record a usable ECG and 11 ( 2.6 % ) three lead ECGs required a clarifying 12 lead ECG . CONCLUSIONS Three lead screening for AF is feasible , effective and offers an alternative to pulse taking or 12 lead ECGs . The availability of this technology may facilitate more effective screening , leading to reduced stroke incidence Objectives To assess whether screening improves the detection of atrial fibrillation  ( cluster r and omisation ) and to compare systematic and opportunistic screening . Design Multicentred cluster r and omised controlled trial , with subsidiary trial embedded within the intervention arm . Setting 50 primary care centres in Engl and , with further individual r and omisation of patients in the intervention practice s. Participants 14 802 patients aged 65 or over in 25 intervention and 25 control practice s. Interventions Patients in intervention practice s were r and omly allocated to systematic screening ( invitation for electrocardiography ) or opportunistic screening ( pulse taking and invitation for electrocardiography if the pulse was irregular ) . Screening took place over 12 months in each practice from October 2001 to February 2003 . No active screening took place in control practice s. Main outcome measure Newly identified atrial fibrillation . Results The detection rate of new cases of atrial fibrillation was 1.63 % a year in the intervention practice s and 1.04 % in control practice s ( difference 0.59 % , 95 % confidence interval 0.20 % to 0.98 % ) . Systematic and opportunistic screening detected similar numbers of new cases ( 1.62 % v 1.64 % , difference 0.02 % , −0.5 % to 0.5 % ) . Conclusion Active screening for atrial fibrillation detects additional cases over current practice . The preferred method of screening in patients aged 65 or over in primary care is opportunistic pulse taking with follow-up electrocardiography . Trial registration Current Controlled Trials IS RCT N19633732 INTRODUCTION AND OBJECTIVES Atrial fibrillation constitutes a serious public health problem because it can lead to complications . Thus , the management of this arrhythmia must include not only its treatment , but antithrombotic therapy as well . The main goal is to determine the proportion of cases of undiagnosed atrial fibrillation and the proportion of patients not being treated with oral anticoagulants . METHODS A multicenter , population -based , retrospective , cross-sectional , observational study . In all , 1043 participants over 60 years of age were r and omly selected to undergo an electrocardiogram in a prearranged appointment .  Demographic data , CHA2DS2-VASc and HAS-BLED scores , international normalized ratio results , and reasons for not receiving oral anticoagulant therapy  were recorded . RESULTS The overall prevalence of atrial fibrillation was 10.9 % ( 95 % confidence interval , 9.1%-12.8 % ) , 20.1 % of which had not been diagnosed previously . In the group with known atrial fibrillation , 23.5 % of those with CHA2DS2-VASc≥2 were not receiving oral anticoagulant therapy , and 47.9 % had a HAS-BLED score≥3 . The odds ratio for not being treated with oral anticoagulation  was 2.04 ( 95 % confidence interval , 1.11 - 3.77 ) for women , 1.10 ( 95 % confidence interval , 1.05 - 1.15 ) for more advanced age at diagnosis , and 8.61 ( 95 % confidence interval 2.38 - 31.0 ) for a CHA2DS2-VASc score<2 . Cognitive impairment ( 15.2 % ) was the main reason for not receiving oral anticoagulant therapy . CONCLUSIONS The prevalence of previously undiagnosed atrial fibrillation in individuals over 60 years of age is 20.1 % , and 23.5 % of those who have been diagnosed receive no treatment with oral anticoagulants AIM Atrial fibrillation ( AF ) is associated with high morbidity and mortality . Early diagnosis is likely to improve therapy and prognosis . The study objective was to evaluate the usefulness of a programme for early diagnosis of AF in patients from an urban primary care centre . METHODS AND RESULTS Participants were recruited from a r and omized sample of patients not diagnosed with AF but having relevant risk factors : age ≥ 65 years , ischaemic and /or valvular heart disease , congestive heart failure , hypertension , and /or diabetes . Patients were r and omly assigned to the intervention group ( IG ) or control group ( CG ) . The intervention included ( i ) initial visit with clinical history , electrocardiogram , and instruction about pulse palpation and warning signs and ( ii ) electrocardiogram every 6 months during a 2-year follow-up . The main endpoint of the study was the proportion of new cases diagnosed at 6 months . Secondary endpoints were number of new AF diagnoses and complications associated with the arrhythmia in both groups . A total of 928 patients were included ( 463 IG and 465 CG ) . At 6 months , AF was diagnosed in 8 IG patients and 1 CG patient ( 1.7 vs. 0.2 % , respectively , P = 0.018 ) . After 2 years of follow-up , 11 IG patients and 6 CG patients had newly diagnosed AF ( 2.5 vs. 1.3 % , respectively , P = 0.132 ) . Time to first diagnosis of AF was shorter in IG patients [ median ( inter-quartile range ) : 7 ( 192 ) days vs. 227 ( 188.5 ) days in CG , P = 0.029 ] . CONCLUSION The simple screening proposed could be useful for the early detection of AF in primary care BACKGROUND R and omized trials have shown a beneficial effect of anticoagulation with warfarin to prevent stroke in atrial fibrillation . It is not known whether the same effect will be obtained in actual practice . The authors conducted a prospect i ve observational study to evaluate the effect of preventive anticoagulation in patients with atrial fibrillation in 2 practice setting s in Montreal . METHODS Of the 1725 out patients screened between October 1990 and September 1993 at a community hospital and a university-affiliated hospital , 221 with documented atrial fibrillation were enrolled and followed up for a mean of 27 months . Most ( 75 % ) of the patients excluded did not meet the inclusion criteria ( because of , for example , an artificial heart valve , mitral stenosis , cardiac transplantation or transient atrial fibrillation ) ; the remainder had not completed enrollment before the end of the study . Following the baseline visit , patients were interviewed by telephone every 6 months , and reported events were confirmed through review of the patients ' charts . Hazards for stroke and for stroke and transient ischemic attack ( TIA ) combined were calculated for each of 4 treatment groups : ASA , warfarin , blended treatment and no treatment , based on the type of anticoagulation therapy patients received during the entire observation period . The blended-treatment group consisted of patients who started on one active therapy and switched to the other or who switched treatments more than once . Corresponding rate ratios ( RRs ) and 95 % confidence intervals ( CIs ) were calculated with reference to the no-treatment group . Cox proportional hazards analysis was used to adjust for differences in patient characteristics . The rates of bleeding episodes were also analysed . RESULTS On average , the study patients were older ( 71.6 [ st and ard deviation 9.3 ] years ) and had a higher prevalence of underlying heart disease ( 52.0 % ) than those in the r and omized trials . Nineteen patients had a first stroke : 4 in the ASA group , 4 in the warfarin group , 4 in the blended-treatment group and 7 in the no-treatment group , for rates of 5.2 , 1.8 , 5.3 and 5.9 per 100 person-years , respectively . Only warfarin was associated with a significantly lower risk of stroke compared with no anticoagulant therapy ( RR 0.31 , 95 % CI 0.09 - 1.00 ) . A similar protective effect of warfarin was found for stroke and TIA combined ( 2.3 v. 6.7 per 100 person-years ; RR 0.34 , 95 % CI 0.12 - 0.99 ) ; the effect of ASA and blended treatment was not significantly different from no treatment . The rate per 100 person-years of any bleeding was not significantly higher for any treatment group ( ASA 2.5 , warfarin 3.4 and blended treatment 3.5 ) compared with the no-treatment group ( 1.9 ) . Patients receiving warfarin had a significantly greater risk of any bleeding event than patients not receiving anticoagulant therapy ( RR 1.79 , 95 % CI 1.07 - 3.00 ) . INTERPRETATION The relative effect of anticoagulant therapy with warfarin in preventing stroke in these practice setting s was equivalent to that in the r and omized trials , although these patients were older and sicker . This preventive treatment is likely to confer additional benefit as it is more widely prescribed Background and Purpose — Stroke risk increases with age in patients who have nonvalvular atrial fibrillation . It is uncertain whether the efficacy of stroke prevention therapies in atrial fibrillation changes as patients age . The objective of this study was to determine the effect of age on the relative efficacy of oral anticoagulants ( OAC ) and antiplatelet ( AP ) therapy ( including acetylsalicylic acid and triflusal ) on ischemic stroke , serious bleeding , and vascular events in patients with atrial fibrillation . Methods — This is an analysis of the Atrial Fibrillation Investigators data base , which contains patient level- data from r and omized trials of stroke prevention in atrial fibrillation . We used Cox regression models with age as a continuous variable that controlled for sex , year of r and omization , and history of cerebrovascular disease , diabetes , hypertension , and congestive heart failure . Outcomes included ischemic stroke , serious bleeding ( intracranial hemorrhage or systemic bleeding requiring hospitalization , transfusion , or surgery ) , and cardiovascular events ( ischemic stroke , myocardial infa r 
    Output:
    