title: Accuracy of the avosure PT pro system compared with a hospital laboratory standard.
abstract: OBJECTIVE
  To compare international normalized ratio (INR) values obtained using the AvoSure PT Pro point-of-care (POC) system with those obtained using a standard laboratory method.
  
  
  METHODS
  Forty-one INR values obtained from the POC system were compared with those obtained from a standard laboratory method. The POC method was evaluated for both laboratory and clinical agreement. To evaluate laboratory agreement, various analyses were used, including mean-squared prediction error (MSE) and mean prediction error (ME), Bland-Altman analysis, correlation, and paired t-test comparing group INR means. For clinical accuracy, discrepant pairs were identified and evaluated to determine whether dosage adjustments would have been needed based on values obtained.
  
  
  RESULTS
  The POC system demonstrated modest precision (MSE = 0.147, 95% CI 0.065 to 0.228) and relatively little bias (ME = 0.090, 95% CI -0.025 to 0.205). Bland-Altman analysis also suggested good agreement at average INRs from 2.0 to 3.0. At average INR values >3.0, the POC system consistently overestimated INR. Values obtained with the POC system were significantly correlated with those obtained from the hospital laboratory (r = 0.77; p < 0.001). Similarly, mean +/- SD POC INR did not differ significantly from the laboratory-determined INR (2.45+/-0.59 vs. 2.37+/-0.48, respectively; p = 0.176). Regarding clinical accuracy, the values clinically agreed in 85.4% of the cases.
  
  
  CONCLUSIONS
  The AvoSure PT Pro POC system appears to be useful for INR values within the 2.0-3.0 range, but values outside of this range should probably be confirmed with a standard laboratory method.
authors.affiliation: The University of Michigan Health System, Ann Arbor 48109-0008, USA.
authors.forename: Janene M
authors.initials: JM
authors.lastname: Rigelsky
authors.forename: Hae Mi
authors.initials: HM
authors.lastname: Choe
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Curtis
authors.forename: Marcia J
authors.initials: MJ
authors.lastname: Brosnan
authors.forename: Sonya
authors.initials: S
authors.lastname: Mitrovich
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Streetman
mesh_terms: D000925:Anticoagulants / Q000097:blood*; D005260:Female; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008824:Michigan; D008875:Middle Aged; D019095:Point-of-Care Systems; D011786:Quality Control; D014859:Warfarin / Q000097:blood*
chemical_list: D000925:Anticoagulants; D014859:Warfarin