Are the Pfa-100® Closure Time and the Skin Bleeding Time Useful in the Diagnostic Work-Up of Patients with Bleeding Diathesis? Correlation with the Severity of Bleeding Symptoms and Sensitivity for Known Defects of Primary Hemostasis.

We compared the performance of PFA-100® closure time (CT) and the skin bleeding time (BT) in the diagnostic work-up of 128 consecutive patients referred to our Centre from June 2002 through June 2003 to be screened for bleeding disorders, due to the presence of bleeding symptoms or the casual finding of abnormal screening tests of hemostasis. The correlation with the severity of the bleeding symptoms and the sensitivity of BT and PFA-100® CT for known defects of primary hemostasis were evaluated. All patients underwent a careful medical interview and were assigned a “bleeding score”, based on the number, type, frequency and severity (development of anemia, need for blood transfusion and/or surgical or medical intervention) of bleeding symptoms. In addition, all patients underwent a first-line screening, which included prothrombin time, activated partial thromboplastin time (APTT), BT and PFA-100® CT (with both the collagen-ADP and the collagen-epinephrine cartridges). The search for Von Willebrand disease (VWD), platelet function disorders (PFD), clotting factor defects and abnormalities of fibrinolysis was performed according to the results of the first line screening tests and the severity and type of bleeding history. Seven (6%) patients had type-1 VWD, 12 (9%) PFD, 29 (23%) defects of clotting factors, 18 (14%) had prolongations of the APTT due to abnormalities that are not associated with bleeding (factor XII deficiency and lupus anticoagulant), while in 63 (49%) all tests gave normal results. The sensitivity of PFA-100® for VWD was 86% (both cartridges), for PFD 75% (collagen-epinephrine) and 8% (collagen-ADP). The sensitivity of BT for VWD was 29%, for PFD 33%. The CT of the PFA-100® CT collagen-epinephrine cartridge was mildly prolonged in 38% of patients with clotting factor deficiency. After dividing the patient population in four quartiles of distribution, according to the severity of the bleeding score (null, low, intermediate and severe), only the CT of the PFA-100® CT collagen-epinephrine cartridge showed a progressive and significant prolongation from the first to the fourth quartile (p=0.04). No association of BT and collagen-ADP CT with the severity of bleeding history was found. In conclusion: 1) CT of the PFA-100® collagen-epinephrine cartridge was significantly associated with the severity of the bleeding history; 2) PFA-100® CT showed a better sensitivity than BT for VWD and PFD; 3) at variance with the BT, PFA-100® could help to discriminate between VWD (prolongation of CT of both cartridges) and PFD (prolongation of CT of the collagen-epinephrine cartridge only).