title: Reliability of delayed INR determination: implications for decentralized anticoagulant care with off-site blood sampling.
abstract: In order to develop decentralized anticoagulant care by off-site blood sampling and transport of samples to a centralized laboratory for International Normalized Ratio (INR) determination we have performed a direct comparative study of INR stability. Analysis was performed daily for 5 d using nine thromboplastins. The overall mean difference of INR after 3d was only 0.05 INR units for samples with a therapeutic INR. After 5 d there was a mean difference of 0.11 INR units with 'non-Manchester' reagents and 0.44 INR units with 'Manchester' reagents. With over-anticoagulated samples mean differences of 0.55-0.72 INR units were observed after 3 d and 1.16-2.46 INR units after 5 d. Although there was some variation in stability of results with different thromboplastins, the difference over time with each thromboplastin was much less than the difference between thromboplastins. In conclusion, there is no clinically significant change in INR when analysis is delayed for up to 3 d. Off-site blood sampling can accommodate a large increase in patient workload without a major revenue increase in primary care and with continued total quality management and central expert advice.
authors.affiliation: Department of Haematology, Addenbrooke's NHS Trust, Cambridge.
authors.forename: T
authors.initials: T
authors.lastname: Baglin
authors.forename: R
authors.initials: R
authors.lastname: Luddington
mesh_terms: D001778:Blood Coagulation Disorders / Q000628:therapy*; D001780:Blood Coagulation Tests / Q000592:standards*; D006801:Humans; D011517:Prothrombin Time; D015203:Reproducibility of Results; D013048:Specimen Handling; D013925:Thromboplastin / Q000032:analysis*; D013997:Time Factors
chemical_list: D013925:Thromboplastin