title: [Incidence of aspirin resistance in the patient group of a university hospital in Korea].
abstract: BACKGROUND
  Aspirin is the most common drug used for the prevention of arterial thrombosis. However, platelet responsiveness to aspirin is variable among individuals and it is important to detect aspirin resistance to improve clinical outcome. We analyzed the changes of platelet reactivity before and after aspirin treatment. We also investigated the incidence and influencing factors of aspirin resistance in Korean.
  
  
  METHODS
  We tested platelet function in 198 patients who had been treated with aspirin in a Korean university hospital, and 59 of these patients were tested for platelet function before and after aspirin treatment. We also analyzed platelet reactivity in 136 patients who had not been treated with aspirin. Platelet function was tested using the VerifyNow Aspirin Assay (Accumetrics, USA). Platelet reactivity was expressed as aspirin reaction unit (ARU) and > or =550 ARU was defined as aspirin resistance.
  
  
  RESULTS
  Platelet reactivity of 136 patients who had not been treated with aspirin was 632.2plusmn;46.3 ARU (meanplusmn;SD) (range, 462-675). Platelet reactivity of 198 patients who had been treated with aspirin was 472.5plusmn;60.0 (338-666) ARU, and 10.1% of patients were aspirin-resistant. The difference of platelet reactivity before and after aspirin treatment was 128.3plusmn;68.7 (-40-248) ARU. Hb level was lower and platelet count was higher in aspirin-resistant group than in aspirin-sensitive group (P<0.05).
  
  
  CONCLUSIONS
  We demonstrated the distribution of platelet reactivity before and after aspirin treatment using the VerifyNow Aspirin Assay. The incidence of aspirin resistance was 10.1%, and low Hb level and high platelet count were related with aspirin resistance.
authors: Department of Laboratory Medicine, Hallym University College of Medicine, Chuncheon, Korea. lyoungk@hallym.or.kr
authors: Young Kyung
authors: YK
authors: Lee
authors: Han-Sung
authors: HS
authors: Kim
authors: Ji-Young
authors: JY
authors: Park
authors: Hee Jung
authors: HJ
authors: Kang
mesh_terms: D000368:Aged; D001241:Aspirin / Q000494:pharmacology / Q000627:therapeutic use*; D004351:Drug Resistance; D005260:Female; D006785:Hospitals, University; D006801:Humans; D007723:Korea / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D010979:Platelet Function Tests; D011237:Predictive Value of Tests
chemical_list: D010975:Platelet Aggregation Inhibitors; D001241:Aspirin