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 .
Clopidogrel for Coronary Stenting Response Variability, Drug Resistance, and the Effect of Pretreatment Platelet Reactivity
Background Clopidogrel is administered to prevent stent thrombosis ; however , the uniformity of platelet inhibition after treatment and the influence of pretreatment reactivity on drug response have not been described . Methods and Results Platelet aggregation ( 5 and 20 μmol/L ADP ) , the activation of glycoprotein IIb/IIIa ( PAC‐1 antibody ) , and the expression of P‐selectin were measured in patients undergoing elective coronary stenting ( n=96 ) at baseline and at 2 hours , 24 hours , 5 days , and 30 days after stenting . All patients received aspirin ( 325 mg ) . Clopidogrel ( 300 mg ) was administered in the catheterization laboratory and followed by 75 mg daily . There was marked interindividual variability in drug response as measured by all markers that showed a normal distribution . Resistance , defined as baseline aggregation ( % ) minus posttreatment aggregation ( % ) ≤10 % by 5 μmol/L ADP , was present in 31 % and 15 % of patients at 5 and 30 days , respectively . Patients with the highest pretreatment platelet reactivity remained the most reactive at 24 hours after treatment ( P<0.0001 ) . Conclusions Interindividual variability in the platelet inhibitory response  from clopidogrel occurs in patients undergoing elective coronary stenting . Patients with high pretreatment reactivity are least protected . Alternative pharmacological strategies and the association of adverse ischemic events should be investigated in these patients . ( Circulation . 2003 ; 107:2908‐2913 .
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 .