Comparison between international normalized ratio using a portable device and conventional methodology.
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.
De Piano
Luciana Pereira Almeida
LP
Heart Institute (InCor), University of São Paulo Medical School, São Paulo, SP, Brazil.
Strunz
Célia Maria Cássaro
CM
Mansur
Antonio de Pádua
Ade P
Rached
Roberto Abi
RA
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
D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight