title: Comparison of the INR Values Measured by CoaguChek XS Coagulometer and Conventional Laboratory Methods in Patients on VKA Therapy.
abstract: BACKGROUND
  Warfarin, which is a widely used oral anticoagulant, has a narrow therapeutic window and requires regular international normalized ratio (INR) monitoring to maintain optimal anticoagulation. Recently, several portable coagulometers have been developed to measure INR levels.
  
  
  OBJECTIVE
  To compare the INR results obtained by a portable coagulometer (CoaguChek XS) and a standard laboratory method (STAGO STA-R).
  
  
  METHODS
  Overall, 433 consecutive patients (male: 191, median age: 61 [44-86] years) who were admitted to outpatient anticoagulation clinic were enrolled in this study. Each patient was tested for INR using portable CoaguChek XS and STAGO STA-R automatic laboratory coagulometer. Correlation between methods was assessed using the Pearson correlation test and Cohen κ test. Bland-Altman plot was used to identify mean difference and 95% limits of agreement.
  
  
  RESULTS
  The mean INR values for CoaguChek XS and STAGO STA-R were 2.54 ± 1.17 and 2.79 ± 1.39, respectively. There was a strong positive correlation between the 2 methods ( r = .966; 95% confidence interval [CI]: 0.95-0.97, P < .001). The Bland-Altman analysis gave a mean difference of 0.26 ± 0.40 between the 2 methods, with a 95% limit of agreement of -0.54 to 1.05. In patients with INR values >5.0, there was only a moderate correlation ( r = .676; 95% CI: 0.38-0.89, P = .002), and the mean difference of INR tended to increase as mean INR values increased. There was a high overall agreement between the 2 methods (κ = .751; 95% CI: 0.69-0.80; P < .001).
  
  
  CONCLUSIONS
  There was good consistency between traditional laboratory testing and CoaguChek XS coagulometer, which provides rapid and reliable INR analysis.
authors.affiliation: 1 Department of Cardiology, Kosuyolu Kartal Heart Training and Research Hospital, Istanbul, Turkey.
authors.forename: Macit
authors.initials: M
authors.lastname: Kalçık
authors.affiliation: 1 Department of Cardiology, Kosuyolu Kartal Heart Training and Research Hospital, Istanbul, Turkey.
authors.forename: Mahmut
authors.initials: M
authors.lastname: Yesin
authors.affiliation: 1 Department of Cardiology, Kosuyolu Kartal Heart Training and Research Hospital, Istanbul, Turkey.
authors.forename: Mustafa Ozan
authors.initials: MO
authors.lastname: Gürsoy
authors.affiliation: 1 Department of Cardiology, Kosuyolu Kartal Heart Training and Research Hospital, Istanbul, Turkey.
authors.forename: Sabahattin
authors.initials: S
authors.lastname: Gündüz
authors.affiliation: 1 Department of Cardiology, Kosuyolu Kartal Heart Training and Research Hospital, Istanbul, Turkey.
authors.forename: Süleyman
authors.initials: S
authors.lastname: Karakoyun
authors.affiliation: 1 Department of Cardiology, Kosuyolu Kartal Heart Training and Research Hospital, Istanbul, Turkey.
authors.forename: Mehmet Ali
authors.initials: MA
authors.lastname: Astarcıoğlu
authors.affiliation: 1 Department of Cardiology, Kosuyolu Kartal Heart Training and Research Hospital, Istanbul, Turkey.
authors.forename: Emrah
authors.initials: E
authors.lastname: Bayam
authors.affiliation: 1 Department of Cardiology, Kosuyolu Kartal Heart Training and Research Hospital, Istanbul, Turkey.
authors.forename: Sinan
authors.initials: S
authors.lastname: Cerşit
authors.affiliation: 1 Department of Cardiology, Kosuyolu Kartal Heart Training and Research Hospital, Istanbul, Turkey.|2 Division of Health Sciences, University of Ardahan, Ardahan, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Özkan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000494:pharmacology / Q000627:therapeutic use; D001777:Blood Coagulation / Q000187:drug effects; D001780:Blood Coagulation Tests / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D019411:Clinical Laboratory Techniques / Q000295:instrumentation / Q000379:methods / Q000592:standards; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D006801:Humans; D019934:International Normalized Ratio / Q000295:instrumentation / Q000592:standards*; D008297:Male; D008875:Middle Aged; D014812:Vitamin K / Q000037:antagonists & inhibitors*; D014859:Warfarin / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D000925:Anticoagulants; D014812:Vitamin K; D014859:Warfarin
keywords: international normalized ratio; oral anticoagulation; point-of-care systems; warfarin