title: Harmonizing the International Normalized Ratio (INR) : Standardization of Methods and Use of Novel Strategies to Reduce Interlaboratory Variation and Bias.
abstract: OBJECTIVE
  To reduce interlaboratory variation and bias in international normalized ratio (INR) results, as used to monitor patients receiving vitamin K antagonist therapy, including warfarin, in a large pathology network (n = 27 laboratories) by procedural standardization and harmonization.
  
  
  METHODS
  Network consensus to standardize to common instrument and reagent platforms was established, following development of hemostasis test specifications. Subsequent installations and implementation occurred after conclusion of a government tender process. Network-wide application of simple novel process of verification harmonization of local international sensitive index and mean normal prothrombin time initiated for each new lot of INR reagent that does not require ongoing use of reference thromboplastin or calibration/certified plasma sets.
  
  
  RESULTS
  We achieved reduction of different instrument manufacturers (from four to one), instrument types (10 to three), reagent types (four to one), and instrument/reagent combinations (12 to three), plus substantial reduction in INR variability and bias.
  
  
  CONCLUSIONS
  Results infer significant improvement in local patient management, with positive implications for other laboratories. For the United States in particular, lack of US Food and Drug Administration-cleared certified plasmas may compromise INR accuracy, and our novel approach may provide a workable alternative for laboratories and networks.
authors.affiliation: From the Haematology Department, Institute of Clinical Pathology and Medical Research (ICPMR), Pathology West, NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia emmanuel.favaloro@health.nsw.gov.au.
authors.forename: Emmanuel J
authors.initials: EJ
authors.lastname: Favaloro
authors.affiliation: From the Haematology Department, Institute of Clinical Pathology and Medical Research (ICPMR), Pathology West, NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia.
authors.forename: Wendy
authors.initials: W
authors.lastname: McVicker
authors.affiliation: From the Haematology Department, Institute of Clinical Pathology and Medical Research (ICPMR), Pathology West, NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia.
authors.forename: Michelle
authors.initials: M
authors.lastname: Lay
authors.affiliation: From the Haematology Department, Institute of Clinical Pathology and Medical Research (ICPMR), Pathology West, NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia.
authors.forename: Monica
authors.initials: M
authors.lastname: Ahuja
authors.affiliation: From the Haematology Department, Institute of Clinical Pathology and Medical Research (ICPMR), Pathology West, NSW Health Pathology, Westmead Hospital, Westmead, NSW, Australia.
authors.forename: Yifang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Pathology Department, Pathology West, NSW Health Pathology, Blacktown Hospital, Blacktown, NSW, Australia.
authors.forename: Sayed
authors.initials: S
authors.lastname: Hamdam
authors.affiliation: Haematology Department, Pathology West, NSW Health Pathology, Wagga Wagga, NSW, Australia.
authors.forename: Naomi
authors.initials: N
authors.lastname: Hocker
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use*; D001315:Australia; D015982:Bias; D002138:Calibration; D002568:Certification; D006801:Humans; D007202:Indicators and Reagents / Q000592:standards; D019934:International Normalized Ratio / Q000592:standards*; D007753:Laboratories / Q000592:standards; D010949:Plasma; D011517:Prothrombin Time / Q000592:standards*; D012015:Reference Standards; D015203:Reproducibility of Results; D013925:Thromboplastin / Q000032:analysis; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D007202:Indicators and Reagents; D014859:Warfarin; D013925:Thromboplastin
keywords: EQA; External quality assessment; Harmonization; INR; International normalized ratio; Standardization