Usefulness of PFA-100 testing in the diagnostic screening of patients with suspected abnormalities of hemostasis: comparison with the bleeding time.
BACKGROUND
Global tests of hemostasis that are used to screen patients with clinical suspicion of bleeding disorders should help the physician to identify the phase of the hemostatic system that is abnormal and guide further diagnostic workup.


METHODS
We compared the performance of Platelet Function Analyzer-100 (PFA-100) closure time (CT) with bleeding time (BT), both of which are screening tests for primary hemostasis, in the diagnostic workup of 128 consecutive patients who were screened for bleeding disorders. The sensitivities of BT and PFA-100 CT for known defects of hemostasis were evaluated; in addition, we calculated their correlation with the levels of severity of the bleeding symptoms, which were recorded using a standardized questionnaire.


RESULTS
The sensitivity of PFA-100 testing was 71% for von Willebrand disease (VWD) [with both collagen-adenosine diphosphate (C-ADP) and collagen-epinephrine (C-EPI) cartridges]; 58% (C-EPI) and 8% (C-ADP) for platelet function disorders (PFDs); and the sensitivity of BT was 29% (VWD) and 33% (PFD). C-EPI CT was also prolonged in about 20% of patients with abnormalities of coagulation or fibrinolysis. Only the C-EPI CT was significantly associated with the levels of severity of the patients' bleeding scores.


CONCLUSIONS
BT and C-EPI are insufficiently sensitive to be recommended as hemostasis screening tests. The C-ADP cartridge, which is sensitive to VWD only, might prove useful in further diagnostic workup of defects of primary hemostasis. The association of C-EPI CT with the severity of bleeding symptoms as a useful predictor of risk of bleeding in clinical practise should be tested in properly designed studies.
Dipartimento di Medicina e Specialità Mediche, IRCCS Fondazione Ospedale Maggiore, Mangiagalli e Regina Elena, Italy.
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D000244:Adenosine Diphosphate; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001760:Bleeding Time; D001778:Blood Coagulation Disorders / Q000097:blood / Q000150:complications / Q000175:diagnosis*; D001780:Blood Coagulation Tests / Q000295:instrumentation*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003094:Collagen; D004837:Epinephrine; D004867:Equipment Design; D005260:Female; D006470:Hemorrhage / Q000097:blood / Q000209:etiology*; D006487:Hemostasis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D014842:von Willebrand Diseases / Q000097:blood / Q000150:complications / Q000175:diagnosis
D000244:Adenosine Diphosphate; D003094:Collagen; D004837:Epinephrine