European Concerted Action on Anticoagulation. A multicentre calibration study of WHO international reference preparations for thromboplastin, rabbit (RBT/90) and human (rTF/95).
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.
Poller
L
L
ECAA Central Facility, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK. ecaa@manchester.ac.uk
Keown
M
M
Chauhan
N
N
van den Besselaar
A M H P
AM
Tripodi
A
A
Shiach
C
C
Jespersen
J
J
D000818:Animals; D002138:Calibration; D005060:Europe; D006801:Humans; D019934:International Normalized Ratio / Q000592:standards*; D011517:Prothrombin Time / Q000592:standards; D011817:Rabbits; D012015:Reference Standards; D015203:Reproducibility of Results; D013045:Species Specificity; D013925:Thromboplastin / Q000592:standards*; D014944:World Health Organization
D013925:Thromboplastin