Can the Platelet Function Analyzer (PFA (R))-100 test substitute for the template bleeding time in routine clinical practice?

The bleeding time (BT) is widely used in clinical medicine as a screening t est of platelet function, although its deficiencies in such a role are well recognized. The Platelet Function Analyzer (PFA)(R)-100 measures the abili ty of platelets activated in a high-shear environment to occlude an apertur e in a membrane treated with collagen and epinephrine (CEPI) or collagen an d ADP (CADP), The time taken for flow across the membrane to stop (closure time) is recorded. This study compared the PFA(R)-100 with the BT as a scre ening test of platelet dysfunction in 113 hospital inpatients. The PFA(R)-1 00 test was performed initially using the CEPI cartridge; CADP tests were p erformed on those with abnormal (> 163 s) CEPI closure times. Whole blood p latelet aggregation studies and chart review were performed on patients in whom the BT and PFA(R)-100 results did not agree. Abnormal bleeding times a nd PFA(R)-100 results were obtained in 20.4% and 35.4% of patients, respect ively. The results of BT and PFA(R)-100 agreed in 74.3% of patients. Of the 29 patients in whom the BT and PFA(R)-100 results were discordant, whole b lood platelet aggregation studies supported the PFA(R)-100 result in 25 (86 .2%). The PFA(R)-100 was more sensitive to aspirin-induced platelet dysfunc tion and was more rapidly and cheaply performed than the BT. Since the PFA( R)-100 test reflects platelet function better than the BT, we conclude that this test could replace the BT as a first-line screening test for platelet dysfunction in clinical practice.