title: Importance of device evaluation for point-of-care prothrombin time international normalized ratio testing programs.
abstract: OBJECTIVE
  To determine the accuracy of 2 commercially available point-of-care devices relative to plasma international normalized ratio (INR) values.
  
  
  METHODS
  Point-of-care INR testing was performed with the CoaguChek and ProTime 3 devices in consecutive patients attending an anticoagulation clinic between June 18, 2003, and August 6, 2003. Results were compared with plasma INRs using a sensitive thromboplastin (International Sensitivity Index, 1.0).
  
  
  RESULTS
  Ninety-four patients agreed to participate in the study. Relative to the plasma INR, values were in agreement +/-0.4 INR unit 82% and 39% of the time for the CoaguChek and ProTime 3 devices, respectively. The mean +/- SD CoaguChek INRs were 0.2+/-0.31 unit lower, whereas ProTime 3 INRs were 0.8+/-0.68 unit higher than plasma INR values. Treatment decisions based on these data would have resulted in inappropriate dose adjustments 10% and 22% of the time for these 2 respective devices. Correlation with plasma was greater for the CoaguChek (r2=0.90) compared with the ProTime 3 device (r2=0.73).
  
  
  CONCLUSIONS
  Optimal warfarin treatment requires accurate measurement of the INR. The choice of a point-of-care device for INR management depends on the reliability of INR data generated by the device.
authors.affiliation: Department of Internal Medicine and Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, Minn 55905, USA. mcbane.robert@mayo.edu
authors.forename: Robert D
authors.initials: RD
authors.lastname: McBane
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Felty
authors.forename: Mindy L
authors.initials: ML
authors.lastname: Hartgers
authors.forename: Rajeev
authors.initials: R
authors.lastname: Chaudhry
authors.forename: Lisa K
authors.initials: LK
authors.lastname: Beyer
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Santrach
mesh_terms: D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D019934:International Normalized Ratio / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D011517:Prothrombin Time / Q000295:instrumentation*; D015203:Reproducibility of Results; D014859:Warfarin / Q000008:administration & dosage
chemical_list: D000925:Anticoagulants; D014859:Warfarin