title: Good short-term but not long-term reproducibility of the antiplatelet efficacy laboratory assessment.
abstract: BACKGROUND
  The antiplatelet effect of acetylsalicylic acid (ASA) varies among individual patients. We assessed the short-term reproducibility (STR) and long-term reproducibility (LTR) of light transmission aggregometry (LTA).
  
  
  METHODS
  Residual platelet reactivity was measured twice using LTA in a group of 207 consecutive patients (56 females, mean age 67 ± 9 years) on ASA therapy in 10 ± 6 months interval. The STR was assessed in 15 patients (6 females, mean age 61 ± 7 years) with 10 measurements on 2 consecutive days.
  
  
  RESULTS
  There was no correlation between both measurements in the long-term part of the study, and also Bland-Altman plot showed a diverging pattern. However, LTA STR was good with a correlation coefficient of .800 (P < .05) confirmed by Bland-Altman plot.
  
  
  CONCLUSIONS
  Although short-term intraindividual reproducibility of LTA assessment of platelet reactivity is very good, in the long-term perspective the antiplatelet ASA effectivity may be influenced by additional variables and repeated measurements are warranted.
authors.affiliation: Department Medicine I, Charles University Prague, School of Medicine, Czech Republic.
authors.forename: Hana
authors.initials: H
authors.lastname: Sevcikova
authors.forename: Jan
authors.initials: J
authors.lastname: Vojacek
authors.forename: Josef
authors.initials: J
authors.lastname: Bis
authors.forename: Robert
authors.initials: R
authors.lastname: Sevcik
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Maly
authors.forename: Miroslav
authors.initials: M
authors.lastname: Pecka
authors.forename: Ilona
authors.initials: I
authors.lastname: Fatorova
mesh_terms: D000368:Aged; D019540:Area Under Curve; D001241:Aspirin / Q000494:pharmacology*; D002318:Cardiovascular Diseases / Q000097:blood; D004347:Drug Interactions; D017097:Electric Impedance; D005260:Female; D005500:Follow-Up Studies; D006629:Hirudins / Q000494:pharmacology; D006801:Humans; D007674:Kidney Diseases / Q000097:blood; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D009765:Obesity / Q000097:blood; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D010979:Platelet Function Tests / Q000379:methods*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012907:Smoking / Q000097:blood; D013997:Time Factors
chemical_list: D006629:Hirudins; D010975:Platelet Aggregation Inhibitors; D001241:Aspirin