title: Comparison between international normalized ratio using a portable device and conventional methodology.
abstract: OBJECTIVE
  to compare the international normalized ratio (INR) measured by a point-of-care (POC) testing device with that measured by the conventional method in patients undergoing anticoagulation therapy with warfarin sodium.
  
  
  METHODS
  The INR of 383 warfarin-treated patients (mean age: 56.5 years; 207 female) was measured in capillary blood using the Hemochron Jr. device and compared with that of venous plasma samples determined by the conventional method performed in a Coag-A-Mate analyzer. Results were evaluated globally and for the following subgroups: INR < 2.0, from 2.0 to 3.5, and > 3.5.
  
  
  RESULTS
  Using both methods, the comparison between INR values yielded a correlation coefficient (r) of 0.86. However, mean differences in INR in both tests, considering the three subgroups, proved to be statistically significant (p <0.001): 0.14 +/- 0.21 (INR< 2.0); 0.54 +/- 0.31 (2.0 < or = INR < or = 3.5), and 1.64 +/- 1.10 (INR> 3.5). Paired Students t-test analysis revealed a p value < 0.001 for the three subgroups studied.
  
  
  CONCLUSIONS
  The use of point-of-care testing for monitoring oral anticoagulation has some limitations. Anticoagulation intensity was underestimated by this method in the three subgroups studied.
authors.affiliation: Heart Institute (InCor), University of São Paulo Medical School, São Paulo, SP, Brazil.
authors.forename: Luciana Pereira Almeida
authors.initials: LP
authors.lastname: De Piano
authors.forename: Célia Maria Cássaro
authors.initials: CM
authors.lastname: Strunz
authors.forename: Antonio de Pádua
authors.initials: Ade P
authors.lastname: Mansur
authors.forename: Roberto Abi
authors.initials: RA
authors.lastname: Rached
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D001777:Blood Coagulation / Q000187:drug effects*; D005260:Female; D006495:Heparin, Low-Molecular-Weight / Q000627:therapeutic use*; D006801:Humans; D019934:International Normalized Ratio / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011517:Prothrombin Time; D012016:Reference Values; D015203:Reproducibility of Results
chemical_list: D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight