title: Evaluation of European Concerted Action on Anticoagulation lyophilized plasmas for INR derivation using the PT/INR line.
abstract: The prothrombin time/international normalized ratio (PT/INR) Line method based on 5 certified European Concerted Action on Anticoagulation (ECAA) plasmas provides reliable local INR values without conventional World Health Organization international sensitivity index calibrations. The present study investigated the use of different numbers and types of ECAA calibrant plasmas to derive accurate PT/INR Lines and reliable INR values. The numbers ranged from 3 to 10 plasmas in a set with normal or abnormal samples. Sets were selected, and sampling was repeated 1,000 times for each center to derive PT/INR Lines. The lines were selected randomly or from clusters. The INR values of 5 independent "validation" plasmas were compared before and after correction. In 56 calibrations, 5 ECAA plasmas gave better results than did fewer plasmas. Plasmas with wide-ranging INR values gave better results than randomly selected sets, and including a normal plasma was not essential. The INR deviations of validation plasmas from certified values were reduced with sets of human, bovine/combined, and rabbit reagents. Deviations of more than 10% from certified INR values were significantly reduced (P < .001).
authors.affiliation: EAA Central Facility, Faculty of Life Sciences, University of Manchester, England.
authors.forename: Saied A
authors.initials: SA
authors.lastname: Ibrahim
authors.forename: Jørgen
authors.initials: J
authors.lastname: Jespersen
authors.forename: Albert
authors.initials: A
authors.lastname: Pattison
authors.forename: Leon
authors.initials: L
authors.lastname: Poller
mesh_terms: D000818:Animals; D002138:Calibration; D002417:Cattle; D005612:Freeze Drying; D006801:Humans; D019934:International Normalized Ratio / Q000592:standards*; D010949:Plasma; D011517:Prothrombin Time; D011817:Rabbits; D012015:Reference Standards; D014944:World Health Organization