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 .
Association of Cyclooxygenase-1–Dependent and –Independent Platelet Function Assays With Adverse Clinical Outcomes in Aspirin-Treated Patients Presenting for Cardiac Catheterization
Background — Poor clinical outcome in  aspirin-treated patients has been termed aspirin resistance and may result from inadequate inhibition of platelet cyclooxygenase-1 ( COX-1 ) by aspirin . The objectives of this study were to determine prospect ively whether COX-1–dependent and other platelet function assays correlate with clinical outcomes in aspirin-treated patients . Methods and Results — Blood was collected before percutaneous coronary intervention from 700 consecutive aspirin-treated ( 81 or 325 mg for ≥3 days ) patients . Platelet function was tested by ( 1 ) serum thromboxane B2 ; ( 2 ) arachidonic acid – stimulated platelet surface P-selectin and activated glycoprotein IIb/IIIa and leukocyte – platelet aggregates ; and ( 3 ) platelet function analyzer (PFA)-100 collagen-epinephrine and collagen-ADP closure time ( CT ) . Adverse clinical outcomes of all-cause death , cardiovascular death , and major adverse cardiovascular events ( cardiovascular death , myocardial infa rct ion , hospitalization for revascularization , or acute coronary syndrome ) were assessed by telephone interview and /or medical record review . Clinical outcomes information was obtained at 24.8±0.3 months after platelet function testing . By univariate analysis , COX-1–dependent assays , including serum thromboxane B2 level , were not associated with adverse clinical outcomes , whereas the COX-1–independent assay , PFA-100 collagen-ADP CT < 65 seconds , was associated with major adverse cardiovascular events ( P=0.0149 ) . After adjustment for covariables ( including sex , aspirin dose , Thrombolysis in Myocardial Infa rct ion risk score , clopidogrel use ) , both serum thromboxane B2 > 3.1 ng/mL and PFA-100 collagen-ADP CT < 65 seconds were associated with major adverse cardiovascular events . In contrast , indirect measures of platelet COX-1 ( arachidonic acid – stimulated platelet markers , shortened PFA-100 collagen-epinephrine CT ) were not significantly associated with adverse clinical outcomes even after adjustment for covariables . Conclusions — In this prospect i ve study of 700 aspirin-treated patients presenting for angiographic evaluation of coronary artery disease , residual platelet COX-1 function measured by serum thromboxane B2 and COX-1–independent platelet function measured by PFA-100 collagen-ADP CT , but not indirect COX-1–dependent assays ( arachidonic acid – stimulated platelet markers , shortened PFA-100 collagen-epinephrine CT ) , correlate with subsequent major adverse cardiovascular events . This study suggests that multiple mechanisms , including but not confined to inadequate inhibition of COX-1 , are responsible for poor clinical outcomes in aspirin-treated patients , and therefore the term aspirin resistance is inappropriate
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 .