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 — Physical activity ( PA ) is well known to reduce the risk of cardiovascular disease . We hypothesized that regular PA , possibly acting through reductions in blood pressure and body mass index ( BMI ) , would reduce the risk of incident atrial fibrillation ( AF ) in women . Methods and Results — We prospect ively followed 34 759 women who reported their leisure-time PA levels for the occurrence of AF . We estimated energy expenditure in metabolic equivalent (MET)-h/wk and vali date d self-reported AF with medical records . The mean ( SD ) age of the 34 759 participants was 54.6 ( 7.0 ) years , the mean BMI was 26.0 ( 5.0 ) kg/m2 , 26.5 % had hypertension , and the median ( IQR ) PA was 8.4 ( 2.8 , 20.4 ) MET-h/wk . After a median of 14.4 years of observation , 968 women had development of AF . In age- , cholesterol- , smoking- , alcohol- , diabetes- , and race-adjusted models , increasing quintiles of PA were associated with reduced risks of AF ( hazard ratio for extreme quintiles , 0.82 ; 0.66 to 1.01 ; P trend=0.007 over quintiles ) . Although this association was not substantially different after adjusting for hypertension ( 0.87 ; 0.70 to 1.07 ; P trend 0.02 ) , it was attenuated after adjustment for BMI ( 0.99 ; 0.80 to 1.23 ; P trend=0.22 ) . Women who achieved the federal government 's recommendation of 7.5 MET-h/wk of PA were at reduced risk of AF compared with those who did not ( 0.86 ; 0.75 to 0.98 ; P=0.03 ) . This association was also attenuated by BMI ( 0.96 ; 0.84 to 1.10 ; P=0.57 ) . Conclusions — In middle-aged women , physical activity was associated with a modestly reduced risk of AF . However , this relationship was no longer significant after controlling for body mass index Background No previous studies have examined the interplay among socioeconomic status , sex , and race with the risk of atrial fibrillation ( AF ) .  Methods and Results We prospect ively followed 14 352 persons ( 25 % black , 75 % white , 55 % women , mean age 54 years ) who were free of AF and participating in the Atherosclerosis Risk in Communities ( ARIC ) study .  Socioeconomic status was assessed at baseline ( 1987–1989 ) through educational level and total family income . Incident AF through 2009 was ascertained from electrocardiograms , hospitalizations , and death certificates . Cox regression was used to estimate hazard ratios and 95 % CIs of AF for education and family income . Interactions were tested between socioeconomic status and age , race , or sex . Over a median follow‐up of 20.6 years , 1794 AF cases occurred . Lower family income was associated with higher AF risk ( hazard ratio 1.45 , 95 % CI 1.27 to 1.67 in those with income less than $ 25 000 per year compared with those with $ 50 000 or more per year ) . The association between education and AF risk varied by sex ( P=0.01 ) , with the lowest education group associated with higher AF risk in women ( hazard ratio 1.88 , 95 % CI 1.55 to 2.28 ) but not in men ( hazard ratio 1.15 , 95 % CI 0.97 to 1.36 ) compared with the highest education group . Adjustment for cardiovascular risk factors attenuated the associations . There were no interactions with race or age . Blacks had lower AF risk  than whites in all income and education groups . Conclusions Lower family income was associated with a higher AF risk overall , whereas the impact of education on AF risk was present only in women . Differences in socioeconomic status do not explain the lower risk of AF in blacks compared with whites Background —Low-density lipoprotein ( LDL ) cholesterol is a strong risk factor for atherosclerosis but has an inverse association with atrial fibrillation ( AF ) . We aim ed to provide insight into the paradoxical association of LDL cholesterol with AF by evaluating the relationship of various lipoprotein measures and incident AF . Methods and Results —We prospect ively evaluated lipoprotein measures among 23 738 healthy middle-aged and older women ( median follow-up 16.4 years ; N=795 incident AF events ) .  Baseline LDL cholesterol was directly measured , lipoprotein particle concentrations and size were measured by nuclear magnetic resonance spectroscopy , and apolipoproteins were measured by immunoassay . Cox regression models were adjusted for age , AF risk factors , inflammatory , and dysglycemic biomarkers . After multivariable adjustment , inverse associations with AF were observed ( hazard ratio , 95 % confidence interval for top versus bottom quintile , P value ) for LDL cholesterol ( 0.72 , 0.56–0.92 , P=0.009 ) , the total number of LDL particles ( 0.77 , 0.60–0.99 , P=0.045 ) , and very-low-density lipoprotein particles ( 0.78 , 0.61–0.99 , P=0.04 ) , which was driven by the number of cholesterol-poor small LDL ( 0.78 , 0.61–1.00 , P=0.05 ) and small very-low-density lipoprotein particles ( 0.78 , 0.62–0.99 , P=0.04 ) . By contrast , the larger cholesterol-rich LDL particles and all high-density lipoprotein measures were not associated with AF in multivariable models . Adjustment for inflammatory and dysglycemic biomarkers had minimal impact on these associations . Conclusions —In this prospect i ve study , the inverse association between LDL cholesterol and AF extended to several other atherogenic lipoproteins , and these associations are unlikely to be mediated by direct cholesterol effects . Clinical Trial Registration — Clinical Trials.gov ; Unique Identifier : NCT00000479 Summary Background The associations of blood pressure with the different manifestations of incident cardiovascular disease in a contemporary population have not been compared . In this study , we aim ed to analyse the associations of blood pressure with 12 different presentations of cardiovascular disease . Methods We used  linked electronic health records from 1997 to 2010 in the CALIBER ( CArdiovascular research using LInked Bespoke studies and Electronic health Records ) programme to assemble a cohort of 1·25 million patients , 30 years of age or older and initially free from cardiovascular disease , a fifth of whom received blood pressure-lowering treatments . We studied the heterogeneity in the age-specific associations of clinical ly measured blood pressure with 12 acute and chronic cardiovascular diseases , and estimated the lifetime risks ( up to 95 years of age ) and cardiovascular disease-free life-years lost adjusted for other risk factors at index ages 30 , 60 , and 80 years . This study is registered at Clinical Trials.gov , number NCT01164371 . Findings During 5·2 years median follow-up , we recorded 83 098 initial cardiovascular disease presentations . In each age group , the lowest risk for cardiovascular disease was in people with systolic blood pressure of 90–114 mm Hg and diastolic blood pressure of 60–74 mm Hg , with no evidence of a J-shaped increased risk at lower blood pressures . The effect of high blood pressure varied by cardiovascular disease endpoint , from strongly positive to no effect . Associations with high systolic blood pressure were strongest for intracerebral haemorrhage ( hazard ratio 1·44 [ 95 % CI 1·32–1·58 ] ) , subarachnoid haemorrhage ( 1·43 [ 1·25–1·63 ] ) , and stable angina ( 1·41 [ 1·36–1·46 ] ) , and weakest for abdominal aortic aneurysm ( 1·08 [ 1·00–1·17 ] ) . Compared with diastolic blood pressure , raised systolic blood pressure had a greater effect on angina , myocardial infa rct ion , and peripheral arterial disease , whereas raised diastolic blood pressure had a greater effect on abdominal aortic aneurysm than did raised systolic pressure . Pulse pressure associations were inverse for abdominal aortic aneurysm ( HR per 10 mm Hg 0·91 [ 95 % CI 0·86–0·98 ] ) and strongest for peripheral arterial disease ( 1·23 [ 1·20–1·27 ] ) . People with  hypertension ( blood pressure ≥140/90 mm Hg or those receiving blood pressure-lowering drugs ) had a lifetime risk of overall cardiovascular disease at 30 years of age of 63·3 % ( 95 % CI 62·9–63·8 ) compared with 46·1 % ( 45·5–46·8 ) for those with normal blood pressure , and developed cardiovascular disease 5·0 years earlier ( 95 % CI 4·8–5·2 ) . Stable and unstable angina accounted for most ( 43 % ) of the cardiovascular disease-free years of life lost associated with hypertension from index age 30 years , whereas heart failure and stable angina accounted for the largest proportion ( 19 % each ) of years of life lost from index age 80 years . Interpretation The widely held assumptions that blood pressure has strong associations with the occurrence of all cardiovascular diseases across a wide age range , and that diastolic and systolic associations are concordant , are not supported by the findings of this high-resolution study . Despite modern treatments , the lifetime burden of hypertension is substantial . These findings emphasise the need for new  blood pressure-lowering strategies , and will help to inform the design of r and omised trials to assess them . Funding Medical Research Council , National Institute for Health Research , and Wellcome Trust Background Atrial fibrillation ( AF ) is the most common cardiac arrhythmia and is associated with increased risk of stroke and death . Obesity is an independent risk factor for AF , but modifiers of this risk are not well known . We studied the roles of obesity , physical activity , and their interaction in conferring risk of incident AF . Methods and Results The Women 's Health Initiative ( WHI ) Observational Study was a prospect i ve observational study of 93 676 postmenopausal women followed for an average of 11.5 years .  Incident AF was identified using WHI‐ascertained hospitalization records and diagnostic codes from Medicare cl aims . A multivariate Cox 's hazard regression model adjusted for demographic and clinical risk factors was used to evaluate the interaction between obesity and  physical activity and its association with incident AF . After exclusion of women with prevalent AF , incomplete data , or underweight body mass index ( BMI ) , 9792 of the remaining 81 317 women developed AF . Women were , on average , 63.4 years old , 7.8 % were African American , and 3.6 % were Hispanic .  Increased BMI ( hazard ratio [ HR ] , 1.12 per 5‐kg/m2 increase ; 95 % confidence interval [ CI ] , 1.10 to 1.14 ) and  reduced physical activity  ( > 9 vs. 0 metabolic equivalent task hours per week ; HR , 0.90 ; 95 % CI , 0.85 to 0.96 ) were independently associated with higher rates of AF after multivariate adjustment . Higher  levels of physical activity reduced the AF risk conferred by obesity ( interaction P=0.033 ) . Conclusions  Greater physical activity is associated with lower rates of incident AF and modifies the association between obesity and incident AF Background — Vigorous exertion and endurance training have been reported to increase  atrial fibrillation ( AF ) .  Associations of habitual light or moderate activity with AF incidence have not been evaluated . Methods and Results — We prospect ively investigated associations of leisure-time activity , exercise intensity , and walking habits , assessed at baseline and up date d during follow-up visits , with incident AF , diagnosed by annual 12-lead ECGs and hospital discharge records , from 1989 to 2001 among 5446 adults ≥65 years of age in the Cardiovascular Health Study . During 47 280 person-years of follow-up , 1061 new AF cases occurred ( incidence 22.4/1000 person-years ) . In multivariable-adjusted analyses , leisure-time activity was associated with lower AF incidence in a grade d manner , with 25 % ( hazard ratio [ HR ] 0.75 , 95 % confidence interval [ CI ] 0.61 to 0.90 ) , 22 % ( HR 0.78 , 95 % CI 0.65 to 0.95 ) , and 36 % ( HR 0.64 , 95 % CI 0.52 to 0.79 ) lower risk in quintiles 3 , 4 , and 5 versus quintile 1 ( P for trend < 0.001 ) . Exercise 
    Output:
    
agent
A systematic evaluation of the available evidence suggests similarities as well as important differences in the risk factors for incidence of AF as compared with other cardiovascular diseases , which has implication s for the primary prevention strategies for atrial fibrillation
***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 — Physical activity ( PA ) is well known to reduce the risk of cardiovascular disease . We hypothesized that regular PA , possibly acting through reductions in blood pressure and body mass index ( BMI ) , would reduce the risk of incident atrial fibrillation ( AF ) in women . Methods and Results — We prospect ively followed 34 759 women who reported their leisure-time PA levels for the occurrence of AF . We estimated energy expenditure in metabolic equivalent (MET)-h/wk and vali date d self-reported AF with medical records . The mean ( SD ) age of the 34 759 participants was 54.6 ( 7.0 ) years , the mean BMI was 26.0 ( 5.0 ) kg/m2 , 26.5 % had hypertension , and the median ( IQR ) PA was 8.4 ( 2.8 , 20.4 ) MET-h/wk . After a median of 14.4 years of observation , 968 women had development of AF . In age- , cholesterol- , smoking- , alcohol- , diabetes- , and race-adjusted models , increasing quintiles of PA were associated with reduced risks of AF ( hazard ratio for extreme quintiles , 0.82 ; 0.66 to 1.01 ; P trend=0.007 over quintiles ) . Although this association was not substantially different after adjusting for hypertension ( 0.87 ; 0.70 to 1.07 ; P trend 0.02 ) , it was attenuated after adjustment for BMI ( 0.99 ; 0.80 to 1.23 ; P trend=0.22 ) . Women who achieved the federal government 's recommendation of 7.5 MET-h/wk of PA were at reduced risk of AF compared with those who did not ( 0.86 ; 0.75 to 0.98 ; P=0.03 ) . This association was also attenuated by BMI ( 0.96 ; 0.84 to 1.10 ; P=0.57 ) . Conclusions — In middle-aged women , physical activity was associated with a modestly reduced risk of AF . However , this relationship was no longer significant after controlling for body mass index Background No previous studies have examined the interplay among socioeconomic status , sex , and race with the risk of atrial fibrillation ( AF ) .  Methods and Results We prospect ively followed 14 352 persons ( 25 % black , 75 % white , 55 % women , mean age 54 years ) who were free of AF and participating in the Atherosclerosis Risk in Communities ( ARIC ) study .  Socioeconomic status was assessed at baseline ( 1987–1989 ) through educational level and total family income . Incident AF through 2009 was ascertained from electrocardiograms , hospitalizations , and death certificates . Cox regression was used to estimate hazard ratios and 95 % CIs of AF for education and family income . Interactions were tested between socioeconomic status and age , race , or sex . Over a median follow‐up of 20.6 years , 1794 AF cases occurred . Lower family income was associated with higher AF risk ( hazard ratio 1.45 , 95 % CI 1.27 to 1.67 in those with income less than $ 25 000 per year compared with those with $ 50 000 or more per year ) . The association between education and AF risk varied by sex ( P=0.01 ) , with the lowest education group associated with higher AF risk in women ( hazard ratio 1.88 , 95 % CI 1.55 to 2.28 ) but not in men ( hazard ratio 1.15 , 95 % CI 0.97 to 1.36 ) compared with the highest education group . Adjustment for cardiovascular risk factors attenuated the associations . There were no interactions with race or age . Blacks had lower AF risk  than whites in all income and education groups . Conclusions Lower family income was associated with a higher AF risk overall , whereas the impact of education on AF risk was present only in women . Differences in socioeconomic status do not explain the lower risk of AF in blacks compared with whites Background —Low-density lipoprotein ( LDL ) cholesterol is a strong risk factor for atherosclerosis but has an inverse association with atrial fibrillation ( AF ) . We aim ed to provide insight into the paradoxical association of LDL cholesterol with AF by evaluating the relationship of various lipoprotein measures and incident AF . Methods and Results —We prospect ively evaluated lipoprotein measures among 23 738 healthy middle-aged and older women ( median follow-up 16.4 years ; N=795 incident AF events ) .  Baseline LDL cholesterol was directly measured , lipoprotein particle concentrations and size were measured by nuclear magnetic resonance spectroscopy , and apolipoproteins were measured by immunoassay . Cox regression models were adjusted for age , AF risk factors , inflammatory , and dysglycemic biomarkers . After multivariable adjustment , inverse associations with AF were observed ( hazard ratio , 95 % confidence interval for top versus bottom quintile , P value ) for LDL cholesterol ( 0.72 , 0.56–0.92 , P=0.009 ) , the total number of LDL particles ( 0.77 , 0.60–0.99 , P=0.045 ) , and very-low-density lipoprotein particles ( 0.78 , 0.61–0.99 , P=0.04 ) , which was driven by the number of cholesterol-poor small LDL ( 0.78 , 0.61–1.00 , P=0.05 ) and small very-low-density lipoprotein particles ( 0.78 , 0.62–0.99 , P=0.04 ) . By contrast , the larger cholesterol-rich LDL particles and all high-density lipoprotein measures were not associated with AF in multivariable models . Adjustment for inflammatory and dysglycemic biomarkers had minimal impact on these associations . Conclusions —In this prospect i ve study , the inverse association between LDL cholesterol and AF extended to several other atherogenic lipoproteins , and these associations are unlikely to be mediated by direct cholesterol effects . Clinical Trial Registration — Clinical Trials.gov ; Unique Identifier : NCT00000479 Summary Background The associations of blood pressure with the different manifestations of incident cardiovascular disease in a contemporary population have not been compared . In this study , we aim ed to analyse the associations of blood pressure with 12 different presentations of cardiovascular disease . Methods We used  linked electronic health records from 1997 to 2010 in the CALIBER ( CArdiovascular research using LInked Bespoke studies and Electronic health Records ) programme to assemble a cohort of 1·25 million patients , 30 years of age or older and initially free from cardiovascular disease , a fifth of whom received blood pressure-lowering treatments . We studied the heterogeneity in the age-specific associations of clinical ly measured blood pressure with 12 acute and chronic cardiovascular diseases , and estimated the lifetime risks ( up to 95 years of age ) and cardiovascular disease-free life-years lost adjusted for other risk factors at index ages 30 , 60 , and 80 years . This study is registered at Clinical Trials.gov , number NCT01164371 . Findings During 5·2 years median follow-up , we recorded 83 098 initial cardiovascular disease presentations . In each age group , the lowest risk for cardiovascular disease was in people with systolic blood pressure of 90–114 mm Hg and diastolic blood pressure of 60–74 mm Hg , with no evidence of a J-shaped increased risk at lower blood pressures . The effect of high blood pressure varied by cardiovascular disease endpoint , from strongly positive to no effect . Associations with high systolic blood pressure were strongest for intracerebral haemorrhage ( hazard ratio 1·44 [ 95 % CI 1·32–1·58 ] ) , subarachnoid haemorrhage ( 1·43 [ 1·25–1·63 ] ) , and stable angina ( 1·41 [ 1·36–1·46 ] ) , and weakest for abdominal aortic aneurysm ( 1·08 [ 1·00–1·17 ] ) . Compared with diastolic blood pressure , raised systolic blood pressure had a greater effect on angina , myocardial infa rct ion , and peripheral arterial disease , whereas raised diastolic blood pressure had a greater effect on abdominal aortic aneurysm than did raised systolic pressure . Pulse pressure associations were inverse for abdominal aortic aneurysm ( HR per 10 mm Hg 0·91 [ 95 % CI 0·86–0·98 ] ) and strongest for peripheral arterial disease ( 1·23 [ 1·20–1·27 ] ) . People with  hypertension ( blood pressure ≥140/90 mm Hg or those receiving blood pressure-lowering drugs ) had a lifetime risk of overall cardiovascular disease at 30 years of age of 63·3 % ( 95 % CI 62·9–63·8 ) compared with 46·1 % ( 45·5–46·8 ) for those with normal blood pressure , and developed cardiovascular disease 5·0 years earlier ( 95 % CI 4·8–5·2 ) . Stable and unstable angina accounted for most ( 43 % ) of the cardiovascular disease-free years of life lost associated with hypertension from index age 30 years , whereas heart failure and stable angina accounted for the largest proportion ( 19 % each ) of years of life lost from index age 80 years . Interpretation The widely held assumptions that blood pressure has strong associations with the occurrence of all cardiovascular diseases across a wide age range , and that diastolic and systolic associations are concordant , are not supported by the findings of this high-resolution study . Despite modern treatments , the lifetime burden of hypertension is substantial . These findings emphasise the need for new  blood pressure-lowering strategies , and will help to inform the design of r and omised trials to assess them . Funding Medical Research Council , National Institute for Health Research , and Wellcome Trust Background Atrial fibrillation ( AF ) is the most common cardiac arrhythmia and is associated with increased risk of stroke and death . Obesity is an independent risk factor for AF , but modifiers of this risk are not well known . We studied the roles of obesity , physical activity , and their interaction in conferring risk of incident AF . Methods and Results The Women 's Health Initiative ( WHI ) Observational Study was a prospect i ve observational study of 93 676 postmenopausal women followed for an average of 11.5 years .  Incident AF was identified using WHI‐ascertained hospitalization records and diagnostic codes from Medicare cl aims . A multivariate Cox 's hazard regression model adjusted for demographic and clinical risk factors was used to evaluate the interaction between obesity and  physical activity and its association with incident AF . After exclusion of women with prevalent AF , incomplete data , or underweight body mass index ( BMI ) , 9792 of the remaining 81 317 women developed AF . Women were , on average , 63.4 years old , 7.8 % were African American , and 3.6 % were Hispanic .  Increased BMI ( hazard ratio [ HR ] , 1.12 per 5‐kg/m2 increase ; 95 % confidence interval [ CI ] , 1.10 to 1.14 ) and  reduced physical activity  ( > 9 vs. 0 metabolic equivalent task hours per week ; HR , 0.90 ; 95 % CI , 0.85 to 0.96 ) were independently associated with higher rates of AF after multivariate adjustment . Higher  levels of physical activity reduced the AF risk conferred by obesity ( interaction P=0.033 ) . Conclusions  Greater physical activity is associated with lower rates of incident AF and modifies the association between obesity and incident AF Background — Vigorous exertion and endurance training have been reported to increase  atrial fibrillation ( AF ) .  Associations of habitual light or moderate activity with AF incidence have not been evaluated . Methods and Results — We prospect ively investigated associations of leisure-time activity , exercise intensity , and walking habits , assessed at baseline and up date d during follow-up visits , with incident AF , diagnosed by annual 12-lead ECGs and hospital discharge records , from 1989 to 2001 among 5446 adults ≥65 years of age in the Cardiovascular Health Study . During 47 280 person-years of follow-up , 1061 new AF cases occurred ( incidence 22.4/1000 person-years ) . In multivariable-adjusted analyses , leisure-time activity was associated with lower AF incidence in a grade d manner , with 25 % ( hazard ratio [ HR ] 0.75 , 95 % confidence interval [ CI ] 0.61 to 0.90 ) , 22 % ( HR 0.78 , 95 % CI 0.65 to 0.95 ) , and 36 % ( HR 0.64 , 95 % CI 0.52 to 0.79 ) lower risk in quintiles 3 , 4 , and 5 versus quintile 1 ( P for trend < 0.001 ) . Exercise 
    Output:
    