TY - JOUR T1 - European Concerted Action on Anticoagulation. A multicentre calibration study of WHO international reference preparations for thromboplastin, rabbit (RBT/90) and human (rTF/95) JF - Journal of Clinical Pathology JO - J Clin Pathol SP - 667 LP - 669 DO - 10.1136/jcp.2004.019810 VL - 58 IS - 6 AU - L Poller AU - M Keown AU - N Chauhan AU - A M H P van den Besselaar AU - A Tripodi AU - C Shiach AU - J Jespersen Y1 - 2005/06/01 UR - http://jcp.bmj.com/content/58/6/667.abstract N2 - A 10 centre calibration was performed after six years to determine the international sensitivity index (ISI) of rTF/95 relative to RBT/90, and to assess any international normalised ratio (INR) bias compared with the original multicentre calibration. After exclusion of one outlying centre, the follow up calibration gave a mean ISI for rTF/95 of 0.99, which although a small difference, is significantly greater than the mean ISI of 0.94 obtained previously. The change in ISI for international reference preparation (IRP) rTF/95 relative to RBT/90 would lead to a slight bias in INR for human compared with rabbit thromboplastins. At a theoretical INR of 3.0, the INR bias is 6.0%, and this is below the accepted 10% level of clinical relevance. Ongoing stability monitoring of World Health Organisation thromboplastin IRP is advised. ER -