***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: Stroke incidence in Copenhagen , Denmark was recorded in a r and om population sample of 19,327 persons invited for two health examinations with 5 years ' interval from 1976 to 1983 . Stroke incidence increased exponentially with age . After adjustment to the age and sex distribution of the Danish population in 1980 , the estimated incidence of first stroke was 1.41/1000 women and 2.48/1000 men ; the total incidence was 1.94/1000 population . Risk factor analysis was based on the initial examination of 13,088 persons greater than 35 years old without previous stroke who responded to the first invitation , in whom 295 first strokes were subsequently observed . We used the regression model of Cox . However , our use of this model differs from the somewhat automatic procedures normally used to develop prognostic models . Evaluation of the causative effect of a particular risk factor requires that the direction of mutual influences between the factor in question and other risk factors is established/postulated . Among the 16 potential risk factors for stroke we examined , significant effects were found for age , sex , household income , smoking habits , systolic blood pressure , diabetes , plasma cholesterol concentration , ischemic heart disease , and atrial fibrillation . No significant effect could be demonstrated for a positive family history of stroke , years of school education , marital status , alcohol consumption , daily use of tranquilizers , body mass index , or postmenopausal hormone treatment Background and Purpose — The role of serum fatty acids as a risk factor for stroke and stroke subtypes is largely unknown . Methods — A prospect i ve nested case-control study of Japanese 40 to 85 years of age was conducted through the use of  frozen serum sample s  from 7450 participants in cardiovascular risk surveys collected from 1984 to 1989 for 1 community and 1989 to 1992 for the other 2 communities . By the end of 1998 , we identified 197 incident strokes whose subtypes were confirmed by imaging studies . Three controls per case were selected by matching for sex , age , community , year of serum storage , and fasting status . Results — Compared with controls , total ( n=197 ) , hemorrhagic ( n=75 ) , and ischemic ( n=122 ) strokes had similar proportions of n3 polyunsaturated fatty acids , lower proportions of linoleic and arachidonic acids , and higher proportions of saturated and monosaturated acids , determined by gas chromatography . The multivariate odds ratios associated with a 1-SD increase in linoleic acid ( 5 % ) after adjustment for hypertension , diabetes , serum total cholesterol , and other cardiovascular risk factors were 0.72 [ 95 % confidence interval ( CI ) , 0.59 to 0.89 ] for total stroke , 0.66 ( 95 % CI , 0.49 to 0.88 ) for ischemic stroke , 0.63 ( 95 % CI , 0.46 to 0.88 ) for lacunar infa rct ion , and 0.81 ( 95 % CI , 0.59 to 1.12 ) for hemorrhagic stroke . The respective odds ratios for saturated fatty acids ( 4 % ) were 1.13 ( 95 % CI , 1.05 to 1.65 ) , 1.35 ( 95 % CI , 1.01 to 1.79 ) , 1.44 ( 95 % CI , 1.03 to 2.01 ) , and 1.21 ( 95 % CI , 0.82 to 1.80 ) . Further adjustment for other fatty acids attenuated these relations , but the relation between linoleic acid and risk of ischemic stroke remained statistically significant . Conclusions — A higher intake of linoleic acid may protect against ischemic stroke , possibly through potential mechanisms of decreased blood pressure , reduced platelet aggregation , and enhanced deformability of erythrocyte cells Background and Purpose — Although aspirin is effective in prevention of stroke , fewer studies have examined the impact of aspirin on stroke morbidity . Methods — The Women ’s Health Study is a completed r and omized , placebo-controlled trial design ed to test the effect of low-dose aspirin and vitamin E in the primary prevention of cardiovascular disease and cancer , which enrolled 39 876 women . We used multinomial logistic regression to evaluate the relationship between r and omized aspirin assignment and functional outcomes from stroke . Possible functional outcomes were neither stroke nor transient ischemic attack ( TIA ) , modified Rankin scale ( mRS ) score 0 to 1 , 2 to 3 , and 4 to 6 . Results — After a mean of 9.9 years of follow-up , 460 confirmed strokes ( 366 ischemic , 90 hemorrhagic , and 4 unknown type ) and 405 confirmed TIAs occurred . With regard to total and ischemic stroke , women who were r and omized to aspirin had a nonsignificant decrease in risk of any outcome compared to women not r and omized to aspirin . This decrease in risk only reached statistical significance for those experiencing TIA compared to participants without stroke or TIA ( odds ratio=0.77 ; 95 % confidence interval , 0.63–0.94 ) . For hemorrhagic stroke , a nonsignificant increase in the risk of achieving an mRS score 2 to 3 or 4 to 6 compared with no stroke or TIA was observed for the women r and omized to aspirin compared to those r and omized to placebo . Conclusions — Results from this large r and omized clinical trial provide evidence that 100 mg of aspirin every other day may reduce the risk of ischemic cerebral vascular events but does not have differential effects on functional outcomes from stroke OBJECTIVE ω-3 fatty acids , including eicosapentaenoic acid ( EPA ) , prevent ischemic stroke . However , the clinical importance of EPA for ischemic stroke and its subtype has not been fully eluci date d. METHODS In a cross-sectional study , we determined whether ω-3 fatty acids were predictive factors for ischemic stroke . We compared common clinical parameters among 65 patients with ischemic stroke and 65 control subjects . The parameters included blood chemistry data ; concentrations of EPA , docosahexaenoic acid , and arachidonic acid ( AA ) ; EPA/AA ratio ; smoking ; alcohol intake ; fish consumption more than four times per week ; and the incidence of underlying diseases . The comparisons were performed using the Mann-Whitney U test , and multiple logistic regression analysis was applied to the significant factors in the non-parametric test . We also applied the same approach to the ischemic stroke subtypes , cardioembolism and large-artery atherosclerosis . RESULTS In the multiple logistic regression analysis after the Mann-Whitney U test , a lower EPA concentration was one of the significant risk factors for ischemic stroke , as were a lower body mass index , lower high-density lipoprotein cholesterol , and smoking ( sensitivity 0.846 , specificity 0.831 , positive predictive value 0.833 ) . In the analysis of subtypes , a lower EPA/AA ratio and a lower body mass index were the significant risk factors for cardioembolism ( sensitivity 0.800 , specificity 0.733 , positive predictive value 0.750 ) . However , large-artery atherosclerosis was not related to the EPA concentration or the EPA/AA ratio . CONCLUSIONS In this study , the plasma EPA concentration and the EPA/AA ratio were potential predictive risk factors for ischemic stroke , especially for cardioembolism . Further prospect i ve studies are necessary Background and Purpose The etiology of ischemic stroke affects prognosis , outcome , and management . Trials of therapies for patients with acute stroke should include measurements of responses as influenced by subtype of ischemic stroke . A system for categorization of subtypes of ischemic stroke mainly based on etiology has been developed for the Trial of Org 10172 in Acute Stroke Treatment ( TOAST ) . Methods A classification of subtypes was prepared using clinical features and the results of ancillary diagnostic studies . “ Possible ” and “ probable ” diagnoses can be made based on the physician 's certainty of diagnosis . The usefulness and interrater agreement of the classification were tested by two neurologists who had not participated in the writing of the criteria . The neurologists independently used the TOAST classification system in their bedside evaluation of 20 patients , first based only on clinical features and then after review ing the results of diagnostic tests . Results The TOAST classification denotes five subtypes of ischemic stroke : 1 ) large-artery atherosclerosis , 2 ) cardioembolism , 3 ) small-vessel occlusion , 4 ) stroke of other determined etiology , and 5 ) stroke of undetermined etiology . Using this rating system , interphysician agreement was very high . The two physicians disagreed in only one patient . They were both able to reach a specific etiologic diagnosis in 11 patients , whereas the cause of stroke was not determined in nine . Conclusions The TOAST stroke subtype classification system is easy to use and has good interobserver agreement . This system should allow investigators to report responses to treatment among important subgroups of patients with ischemic stroke . Clinical trials testing treatments for acute ischemic stroke should include similar methods to diagnose subtypes of stroke Arachidonic acid ( AA ) is the precursor of thromboxane and prostacyclin , two of the most active compounds related to platelet function . The effect of dietary AA on platelet function in humans is not understood although a previous study suggested dietary AA might have adverse physiological consequences on platelet function . Here normal healthy male volunteers ( n=10 ) were fed diets containing 1.7 g/d of AA for 50 d. The control diet contained 210 mg/d of AA .  Platelet aggregation in the platelet-rich plasma was determined using ADP , collagen , and AA . No statistical differences could be detected between the aggregation before and after consuming the high-AA diet . The prothrombin time , partial thromboplastin time , and the antithrombin III levels in the subjects were determined also . There were no statistically significant differences in these three parameters when the values were compared before and after they consumed the high-AA diet . The in vivo bleeding times also did not show a significant difference before and after the subjects consumed the high-AA diet . Platelets exhibited only small changes in their AA content during the AA feeding period . The results from this study on blood clotting parameters and in vitro platelet aggregation suggest that adding 1.5 g/d of dietary AA for 50 d to a typical Western diet containing about 200 mg of AA produces no observable physiological changes in blood coagulation and thrombotic tendencies in healthy , adult males compared to the unsupplemented diet . Thus , moderate intakes of foods high in AA have few effects on blood coagulation , platelet function , or platelet fatty acid composition Background and Purpose — Although studies have linked types of fatty acids with coronary heart disease , data on individual fatty acids and risk of ischemic stroke are limited . We aim ed to examine the associations between serum fatty acid concentrations and incidence of ischemic stroke and its subtypes . Methods — We conducted a prospect i ve case – control study nested in the Women ’s Health Initiative Observational Study cohort of postmenopausal US women aged 50 to 79 years . Between 1993 and 2003 , incident cases of ischemic stroke were matched 1:1 to controls on age , race , and length of follow-up ( 964 matched pairs ) . Conditional logistic regression was used to estimate odds ratios and 99.9 % confidence intervals ( CI ) for ischemic stroke and its subtypes . Results — The multivariable-adjusted odds ratios and 99.9 % CI of ischemic stroke associated with a 1-SD increment in serum fatty acid concentration were 1.38 ( 99.9 % CI , 1.05–1.83 ) for linoelaidic acid ( 18:2tt , SD=0.04 % ) , 1.27 ( 99.9 % CI , 1.06–1.51 ) for palmitic acid ( 16:0 , SD=2.74 % ) , 1.20 ( 99.9 % CI , 1.01–1.43 ) for oleic acid ( 18:1n9 , SD=2.32 % ) , 0.72 ( 99.9 % CI , 0.59–0.87 ) for docosapentaenoic acid ( 22:5n3 , SD=0.18 % ) , 0.72 ( 99.9 % CI , 0.59–0.87 ) for docosahexaenoic acid ( 22:6n3 , SD=0.91 % ) , and 0.81 ( 99.9 % CI , 0.67–0.98 ) for arachidonic acid ( 20:4n6 , SD=2.02 % ) . These associations were generally consistent for atherothrombotic and lacunar stroke but not cardioembolic stroke . Conclusions — These findings suggest that individual serum trans , saturated , and monounsaturated fatty acids are positively associated with particular ischemic stroke subtypes , whereas individual n3 and n6 polyunsaturated fatty acids are inversely associated Background and Purpose We sought to improve the reliability of the Trial of ORG 10172 in Acute Stroke Treatment ( TOAST ) classification of stroke subtype for retrospective use in clinical , health services , and quality of care outcome studies . The TOAST investigators devised a series of 11 definitions to classify patients with ischemic 
    Output:
    
Key Messages : We did not find a positive association between ARA exposure and cerebral ischemia risk .
Eligible studies reported inconsistent findings : cerebral ischemia risk did not change or significantly decreased .