Results indicated that some PFTs may have some prognostic utility , i.e. a trend for more clinical events to be associated with groups classified as ' aspirin resistant ' .
Study -level effect sizes were generally small and absolute outcome risk was not substantially different between ' aspirin resistant ' and ' aspirin sensitive ' design ations .
Based on assumptions of PFTs being able to accurately identify patients at high risk of clinical events and such patients benefiting from treatment modification , the economic model found that a test-treat strategy was likely to be cost-effective .
However , neither assumption is currently evidence based .
BACKGROUND The use of aspirin is well established for secondary prevention of cardiovascular disease .
However , a proportion of patients suffer repeat cardiovascular events despite being prescribed aspirin treatment .
It is uncertain whether or not this is due to an inherent inability of aspirin to sufficiently modify platelet activity .
This report aims to investigate whether or not insufficient platelet function inhibition by aspirin ( ' aspirin resistance ' ) , as defined using platelet function tests ( PFTs ) , is linked to the occurrence of adverse clinical outcomes , and further , whether or not patients at risk of future adverse clinical events can be identified through PFTs .
OBJECTIVES To review systematic ally the clinical effectiveness and cost-effectiveness evidence regarding the association between PFT design ation of ' aspirin resistance ' and the risk of adverse clinical outcome ( s ) in patients prescribed aspirin therapy .
To undertake exploratory model-based cost-effectiveness analysis on the use of PFTs .
Prevalence of platelet nonresponsiveness to aspirin in patients treated for secondary stroke prophylaxis and in patients with recurrent ischemic events.
To determine the prevalence of platelet nonresponsiveness to aspirin treatment for secondary stroke prophylaxis , the authors studied consecutive patients during a 29-month period . Information regarding their ischemic events , risk factors , and medications was collected . Platelet aggregation in response to collagen and arachidonic acid was used to determine platelet responsiveness to aspirin .  A total of 653 patients were evaluated . Of these , 129 patients ( 20 % ) were determined to be nonresponsive to aspirin based on continued platelet aggregation in response to collagen , arachidonic acid , or both . A total of 87 ( 13 % ) of the 653 patients were clinical aspirin failures ( ie , presented with new focal cerebral ischemic symptoms while taking aspirin ) . Of the patients with new cerebral ischemic symptoms , 57 ( 66 % ) were determined to be platelet nonresponsive to aspirin . The odds ratio for platelet nonresponsiveness to aspirin  in patients who suffered a recurrent ischemic event while taking aspirin was 14.25 ( 95 % confidence interval : 8.5 - 23.7 ; P < .5 ) . Continued platelet aggregation despite  aspirin treatment occurred in 20 % of ambulatory patients treated for secondary stroke prophylaxis . The prevalence of nonresponsiveness to aspirin  was statistically higher in those patients who suffered recurrent cerebral ischemia while taking aspirin ( P < .5 ) compared with patients who remained without new ischemic symptoms
Results indicated that some PFTs may have some prognostic utility , i.e. a trend for more clinical events to be associated with groups classified as ' aspirin resistant ' .
Study -level effect sizes were generally small and absolute outcome risk was not substantially different between ' aspirin resistant ' and ' aspirin sensitive ' design ations .
Based on assumptions of PFTs being able to accurately identify patients at high risk of clinical events and such patients benefiting from treatment modification , the economic model found that a test-treat strategy was likely to be cost-effective .
However , neither assumption is currently evidence based .
BACKGROUND The use of aspirin is well established for secondary prevention of cardiovascular disease .
However , a proportion of patients suffer repeat cardiovascular events despite being prescribed aspirin treatment .
It is uncertain whether or not this is due to an inherent inability of aspirin to sufficiently modify platelet activity .
This report aims to investigate whether or not insufficient platelet function inhibition by aspirin ( ' aspirin resistance ' ) , as defined using platelet function tests ( PFTs ) , is linked to the occurrence of adverse clinical outcomes , and further , whether or not patients at risk of future adverse clinical events can be identified through PFTs .
OBJECTIVES To review systematic ally the clinical effectiveness and cost-effectiveness evidence regarding the association between PFT design ation of ' aspirin resistance ' and the risk of adverse clinical outcome ( s ) in patients prescribed aspirin therapy .
To undertake exploratory model-based cost-effectiveness analysis on the use of PFTs .