Platelet function analyzer (PFA-100) in patients with mild-to-moderate bleeding disorders and bleeding disorder of unknown cause.

BACKGROUND

The sensitivity of the platelet function analyzer (PFA-100, Dade Behring Inc) was shown to be high for the detection of von Willebrand disease (VWD), but limited for platelet function defects.

OBJECTIVES

To study the diagnostic utility of PFA-100 in mild-to-moderate bleeding disorders and bleeding disorder of unknown cause (BDUC).

METHODS

PFA-100 closure times (CTs) were measured with collagen-epinephrine (EPI) and collagen-adenosine diphosphate (ADP) cartridges in 818 patients with mild bleeding disorders from the Vienna Bleeding Biobank. Patients on anticoagulation or antiplatelet therapy or thrombocytopenic patients were not included.

RESULTS

Only 2% of the 532 BDUC patients had prolonged CTs in PFA (EPI) and PFA (ADP), and 64% in either PFA (EPI) or PFA (ADP). In total, 34% of BDUC patients did not have prolonged CTs in PFA (EPI) or PFA (ADP). These rates were similar to patients with coagulation factor deficiencies (n = 27). The rate of pathologic CTs was significantly higher in patients with VWD (n = 79) and, although less pronounced, in platelet function defect (n = 180). In 15 of 18 (83%) VWD patients with von Willebrand factor (VWF) antigen and/or VWF ristocetin cofactor activity levels <30 IU/dL, the PFA-100 was prolonged in both cartridges. No association of the PFA-100 with the bleeding severity was observed in BDUC patients. However, prolonged CTs were associated with higher age, lower hematocrit, lower VWF antigen or VWF ristocetin cofactor activity levels, lower platelet counts, and higher fibrinogen levels in BDUC patients.

CONCLUSION

We could not confirm a diagnostic utility for the PFA-100 in mild-to-moderate bleeding disorder patients, and specifically BDUC. No association between PFA-100 results and bleeding severity was observed in BDUC patients.