***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    Input: Summary . Anticardiolipin antibodies , one of the family of ‘ antiphospholipid ’ antibodies , increase the risk of venous thromboembolism in the presence of autoimmune disease . Our objective was to determine prospect ively whether there is a positive association between anticardiolipin antibodies and  venous thromboembolism in ostensibly healthy adults . We conducted a nested case – control study ( n = 317 patients and n = 655 control subjects ) in a longitudinal study of over 20 000 participants . Baseline ( prediagnosis ) anticardiolipin IgG and IgM antibodies were assessed by enzyme‐linked immunoassays . Venous thromboembolism was vali date d using st and ardized criteria for venous thrombosis and pulmonary embolism . There was no association between anticardiolipin antibodies and subsequent venous thromboembolism occurrence , overall or in any subgroup . For example , the multivariate‐adjusted relative risk was 0·88 ( 95 % confidence interval , 0·43 , 1·78 ) for greater than versus less than the 95th percentile of anticardiolipin IgG. In conclusion , in this general population sample  , an elevated anticardiolipin antibody level was not a risk factor for venous thromboembolism Introduction – We have undertaken a prospect i ve study to measure anticardiolipin antibodies of IgG isotype within the first few hours of an acute non‐hemorrhagic stroke . Material and methods – We have collected blood sample s at entry from one hundred patients ( 53 men and 47 women ) , mean age 67.4 years , referred within 6 h of a first‐ever non‐hemorrhagic stroke , and from an equal number of age‐ and gender‐matched control patients . Results – IgG anticardiolipin antibodies were 10 GPL in 26 patients and in 5 controls ( p < 0.0001 , X2 test ) . After logistic regression analysis , increase of IgG anticardiolipin antibodies remained independently associated with stroke ( p = 0.0034 ) , together with hypertension ( p = 0.0009 ) and atrial fibrillation ( p = 0.0238 ) . Conclusion – Our data suggest that the occurrence of elevation of IgG anticardiolipin antibodies in stroke patients should ante date stroke onset and might be a risk factor per se OBJECTIVE To determine whether the presence of anticardiolipin antibodies is a risk factor for ischemic stroke and venous thrombosis in healthy adult men . DESIGN A nested , case-control study in a prospect i ve cohort . SETTING A nationwide study of physicians . PARTICIPANTS The study sample was drawn from the Physicians ' Health Study , a r and omized , double-blind , placebo-controlled trial of aspirin and beta-carotene in 22,071 male physicians . At entry , 68 % of the participants su bmi tted plasma sample s that were subsequently frozen at -80 degrees C. During 60.2 months of follow-up , follow-up for nonfatal outcomes was 99.7 % complete and ascertainment of fatal outcomes was 100 % complete . We identified men with documented ischemic stroke , deep venous thrombosis of the leg , or pulmonary embolus and for whom a plasma sample was available . A control was matched by age , smoking history , and length of follow-up to each of the 100 patients with ischemic stroke and the 90 patients with deep venous thrombosis or pulmonary embolus . MEASUREMENTS Plasma sample s were assessed for IgG anticardiolipin antibodies by enzyme-linked immunosorbent assay . The mean anticardiolipin antibody titers of the case patients in the two diagnostic groups ( ischemic stroke ; venous thrombosis or pulmonary embolus ) were compared with those of the control groups , and relative risks were calculated for patients in increasing percentile categories of anticardiolipin antibodies by conditional logistic regression . RESULTS The anticardiolipin antibody titers were higher in case patients with deep venous thrombosis and pulmonary embolus than in their matched controls ( P = 0.01 ) . Persons with anticardiolipin antibody titers above the 95th percentile had a relative risk for developing deep venous thrombosis or pulmonary embolus of 5.3 ( 95 % CI , 1.55 to 18.3 ; P = 0.01 ) . The anticardiolipin antibody titers in case patients with ischemic stroke and controls were not significantly different ( P > 0.2 ) , and no clear trend of higher risks among those with elevated levels of anticardiolipin antibodies was observed . CONCLUSION An anticardiolipin antibody level above the 95th percentile is an important risk factor for deep venous thrombosis or pulmonary embolus but not for ischemic stroke in healthy adult men CONTEXT The presence of antiphospholipid antibodies ( aPL ) has been associated with vascular occlusive events . However , the role of aPL in predicting ischemic events , particularly recurrent ischemic stroke , is controversial . OBJECTIVE To evaluate the effect of baseline aPL positivity ( ie , positivity for anticardiolipin antibodies [ aCL ] , lupus anticoagulant antibodies [ LA ] , or both ) on subsequent thrombo-occlusive events , including recurrent stroke . DESIGN , SETTING , AND PARTICIPANTS The Antiphospholipid Antibodies and Stroke Study ( APASS ) , a prospect i ve cohort study within the Warfarin vs Aspirin Recurrent Stroke Study ( WARSS ) , a r and omized double-blind trial ( N = 2206 ) conducted at multiple US clinical sites from June 1993 through June 2000 and comparing adjusted-dose warfarin ( target international normalized ratio , 1.4 - 2.8 ) and aspirin ( 325 mg/d ) for prevention of recurrent stroke or death . APASS participants were 1770 ( 80 % ) WARSS participants who consented to enroll in the APASS , with usable baseline blood sample s drawn prior to r and omization to the WARSS and analyzed for aPL status within 90 days of index stroke by a central independent laboratory . Quality assurance was performed on approximately 10 % of sample s by a second independent laboratory . MAIN OUTCOME MEASURE Two-year rate of the composite end point of death from any cause , ischemic stroke , transient ischemic attack , myocardial infa rct ion , deep vein thrombosis , pulmonary embolism , and other systemic thrombo-occlusive events . The primary analysis assessed the outcome associated with aPL positivity within each WARSS treatment group separately , after risk-factor adjustment ( since these aPL-positive vs aPL-negative comparisons were not r and omized ) . RESULTS Of the 1770 APASS patients , 720 ( 41 % ) were classified as aPL-positive and 1050 ( 59 % ) as aPL-negative . There was no increased risk of thrombo-occlusive events associated with baseline aPL status in patients treated with either warfarin ( relative risk [ RR ] , 0.99 ; 95 % confidence interval [ CI ] , 0.75 - 1.31 ; P = .94 ) , or aspirin ( RR , 0.94 ; 95 % CI , 0.70 - 1.28 ; P = .71 ) . The overall event rate was 22.2 % among aPL-positive and 21.8 % among aPL-negative patients . There was no treatment x aPL interaction ( P = .91 ) . Patients with baseline positivity for both LA and aCL antibodies tended to have a higher event rate ( 31.7 % ) than did patients who tested negative for both antibodies ( 24.0 % ) ( unadjusted RR , 1.36 ; 95 % CI , 0.97 - 1.92 ; P = .07 ) . Classification and regression tree analyses did not identify a specific LA test or aCL isotype or titer that was associated with increased risk of thrombo-occlusive event . CONCLUSIONS The presence of aPL ( either LA or aCL ) among patients with ischemic stroke does not predict either increased risk for subsequent vascular occlusive events over 2 years or a differential response to aspirin or warfarin therapy . Routine screening for aPL in patients with ischemic stroke does not appear warranted OBJECTIVE We carried out a prospect i ve analysis of clinical and analytical findings in individuals with antiphospholipid antibodies ( aPL ) . METHODS We prospect ively studied 404 individuals , classified in 2 groups : ( 1 ) patients with primary or secondary antiphospholipid syndrome ( APS , n = 226 ) ; and ( 2 ) asymptomatic carriers of aPL ( n = 178 ) . Patients with APS and thrombosis were treated with dicumarin , and an international normalized ratio around 3.0 ( range 2.5 - 3.5 ) was targeted . Asymptomatic carriers were not treated , but specific prophylaxis with low molecular weight heparin or aspirin was prescribed for the periods when individuals were at increased risk of thrombosis . Both groups of individuals were followed up at semester intervals for 36 months . RESULTS Patients with APS presented with  venous ( n = 106 , 46.9 % ) and /or arterial  ( n = 70 . 31 % )  thrombosis or fetal loss  ( n = 58 out of 112 women of fertility age , 51.8 % ) . At the time of the first thrombotic event , 50.0 % of patients with APS had coincident risk factors for thrombosis ( previous surgery and prolonged immobilization were significantly associated with venous thrombosis , and hypercholesterolemia and arterial hypertension with arterial thrombosis ) . Eighteen patients with APS died during the study period . Recurrence of thrombosis in patients with APS was linked to insufficient anticoagulation . During the followup , no episode of thrombosis was detected in any asymptomatic carrier . The proportion of subjects with aPL was similar in patients and in asymptomatic carriers . The proportion of subjects with aPL decreased during the followup , in both patients and carriers . CONCLUSION Differences between patients and asymptomatic carriers with aPL are at least partially dependent on the proportion of coincident vascular risk factors . The decline in aPL during the followup defines a subgroup in which an anticoagulation suppression assay could be tried Our aim was to determine if anticardiolipin antibodies are an independent risk factor for ischemic stroke and to determine their influence on stroke type and clinical outcome . We prospect ively studied 194 consecutive patients with ischemic stroke admitted within 48 h of stroke . A control group consisted of 100 , age and sex matched , healthy individuals .  Neurological and functional status was assessed on admission , at 30 days , and at 1 year . IgG anticardiolipin antibodies  were significantly more frequent in stroke patients ( 25.3 % ) than controls ( 6 % , p < 0.05 ) . A multivariate analysis suggested that anticardiolipin antibodies are an independent risk factor for ischemic stroke in addition to hypertension and atrial fibrillation ( RR = 2.94 , p < 0.05 ) . Elevated IgG anticardiolipin antibodies were associated with cognitive impairment as measured by the Mini Mental State Examination at 30 days and at 1 year . IgG anticardiolipin antibodies did not correlate with stroke recurrence , or mortality at 30 days or 1 year To date very few studies that analyze the prevalence of anticardiolipin antibodies ( ACA ) in healthy subjects have been reported . No data based on a systematic analysis of normal subjects with positive ACA is available . The aim of the present study was to evaluate the prevalence of ACA ; its clinical significance and relationship to the lupus anticoagulant ( LA ) and other autoimmune parameters in an apparently healthy population . 552 normal blood donors from a blood bank were r and omly selected . ACA positive donors who consented were monitored over a period of twelve months and tested every three months . ACA ( IgG and IgM isotypes ) were quantitated by enzyme linked immunoassay ( ELISA ) . The prevalence for IgG ACA in our donor population was estimated to be 6.5 % , and 9.4 % for IgM ACA , which is similar to the one previously reported for IgG and slightly higher for IgM. It is worth noting that in our study ACA positive donors exhibited a progressive negativization . Eight donors with IgG ACA and seven with IgM ACA remained positive for nine months . Five donors with IgG ACA and four with IgM ACA had family history of thromboembolic disease . One donor with IgG ACA and two with IgM ACA had had unexplained miscarriages in the past . We did not find any relationship between ACA and LA , nor between ACA positivity and the clinical and laboratory data studied . Pseudopositivity for lues was not found . No thrombotic event occurred in donors that were positive for ACA during the 12-month follow-up PURPOSE To assess the natural history and risk factors for thrombosis in a large cohort of unselected patients with antiphospholipid antibodies . PATIENTS AND METHODS Three hundred sixty consecutive patients ( 118 males , 242 females , median age 39 
    Output:
    
LA and aCL were significantly associated with an increased risk of thrombosis , especially arterial , in patients without SLE .