Table 1.

Laboratory tests used to measure the antiplatelet effects of aspirin

Test	Method	Advantages	Limitations
Platelet aggregation	Optical platelet aggregation	Widely available	Not specific
		Correlated with clinical events	Uncertain sensitivity
			Labour intensive
			Operator and interpreter dependent
	Semi-automated platelet aggregometry	Simple	Not specific
	(PFA-100, Ultegra RPFA)	Rapid	Uncertain sensitivity
			Uncertain correlation with clinical events
Bleeding time	Skin bleeding time	Simple	Not specific
		Widely available	Not sensitive
			Operator dependent
			Limited reproducibility
			Uncertain correlation with clinical events
Thromboxane generation	Urinary thromboxane excretion	Correlated with clinical events	Uncertain specificity
			Uncertain sensitivity
			Uncertain reproducibility
			Not widely evaluated

PFA=platelet function analyser; RPFA=rapid platelet function analyser.