Effectiveness of Platelet Function Analyzer-100 for Laboratory Detection of Anti-Platelet Drug-Induced Platelet Dysfunction

BACKGROUND: High on-treatment platelet reactivity (HTPR) is the phenomenon wherein patients exhibit normal platelet activity in laboratory testing despite adequate adherence to anti-platelet treatment. We investigated the detection rates of Platelet Function Analyzer (PFA)-100 (Dade Behring AG, Düdingen, Switzerland) for drug-induced platelet dysfunction and analyzed potential contributors to HTPR with practical PFA-100 data over six years. METHODS: We used data from 6,957 patients who underwent PFA-100 testing after receiving aspirin, clopidogrel, or non-steroidal anti-inflammatory drugs (NSAIDs). Of these, 6,163 patients were tested with only the collagen/epinephrine cartridge (Col/EPI) of PFA-100; 794 were tested with both Col/EPI and the collagen/ADP cartridge (Col/ADP). We calculated PFA-100 closure time (CT) for each drug and compared the clinical and laboratory characteristics of the patients with prolonged CTs and normal CTs (i.e., HTPR). RESULTS: In Col/EPI, 73.2% (365/499), 72.6% (390/537), and 55.3% (3,442/6,228) patients showed prolonged CTs for aspirin, clopidogrel, and NSAIDs, respectively. In Col/ADP, prolonged CTs were observed in 37.4% (34/91), 43.2% (35/81), and 29.6% (200/676) of patients receiving aspirin, clopidogrel, and NSAIDs, respectively. Of the patients tested with both cartridges, 88.9% (48/54), 95.3% (41/43), and 89.0% (577/648) of the patients receiving aspirin, clopidogrel, and NSAIDs had prolonged CTs, and 10.0% (79/794) showed normal CTs regardless of drugs. For clopidogrel users (both cartridges), there were more patients with malignancies in the normal CT than prolonged CT group. CONCLUSIONS: PFA-100 is not sufficiently effective for laboratory screening of drug-induced platelet dysfunction. Malignancy may contribute to clopidogrel-related HTPR in PFA-100.

Effects of oral aspirin on Platelet function analyzer-100 collagen-epinephrine closure time in patients undergoing elective surgery

BACKGROUND: There is a growing need for precise blood coagulation tests in preparation for an operation, as a growing number of patients take aspirin during the run-up to their operation. Against this backdrop, we planned to find what effect aspirin has, if taken regularly prior to an operation, on primary hemostasis. We also attempted to determine the possibility of regional anesthesia in cases which the Platelet function analyzer-100 collagen-epinephrine closure time (PFA-100 C/EPI CT) is prolonged. METHODS: We examined three groups the impact of aspirin on the result of the PFA-100 C/EPI CT: Group A (n = 60) consisted of control; Group B (n = 54) who taking aspirin every day until surgery; and Group C (n = 60) was composed of patients who stopped taking aspirin for 7 days before surgery. PFA-100 collagen adenosine-5-diphosphage closure time were only performed on those with abnormal PFA-100 C/EPI CT. RESULTS: PFA-100 C/EPI CT of Group B was significantly longer than Group C and Group A. There was no distinction between Group A and Group C in terms of the PFA-100 C/EPI CT. CONCLUSIONS: PFA-100 C/EPI CT has better sensitivity and specificity than a bleeding test; moreover, it is an easy-to-use and point-of-care test. We concluded that regional anesthesia can be performed for those who taking aspirin until their surgery despite their prolonged collagen-epinephrine closure time except prolonged collagen adenosine-5-diphosphate closure time.