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 .
A prospective, blinded determination of the natural history of aspirin resistance among stable patients with cardiovascular disease.
OBJECTIVES This study was design ed to determine if aspirin resistance is associated with clinical events . BACKGROUND Aspirin resistance , defined by platelet function testing and presumed clinical unresponsiveness to aspirin , has been previously reported by our group and others . However , little information exists linking the laboratory documentation of aspirin resistance and long-term clinical events . METHODS We prospect ively enrolled 326 stable cardiovascular patients from 1997 to 1999 on aspirin ( 325 mg/day for > or = 7 days ) and no other antiplatelet agents .  We tested for aspirin sensitivity by optical platelet aggregation using adenosine diphosphate ( ADP ) and arachidonic acid ( AA ) . The primary outcome was the composite of death , myocardial infa rct ion ( MI ) , or cerebrovascular accident ( CVA ) . Mean follow-up was 679 + /- 185 days . Aspirin resistance was defined as a mean aggregation of > or = 70 % with 10 microM ADP and > or = 20 % with 0.5 mg/ml AA . RESULTS Of the patients studied , 17 ( 5.2 % ) were aspirin resistant and 309 ( 94.8 % ) were not aspirin resistant . During follow-up , aspirin resistance was associated with an increased risk of death , MI , or CVA compared with patients who were aspirin sensitive ( 24 % vs. 10 % , hazard ratio [ HR ] 3.12 , 95 % confidence interval [ CI ] 1.10 to 8.90 , p = 0.03 ) . Stratified multivariate analyses identified platelet count , age , heart failure , and aspirin resistance to be independently associated with major adverse long-term outcomes ( HR for aspirin resistance 4.14 , 95 % CI 1.42 to 12.06 , p = 0.009 ) . CONCLUSIONS This study demonstrates the natural history of aspirin resistance in a stable population , documenting a greater than threefold increase in the risk of major adverse events associated with aspirin resistance
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 .