Table 3

ISI Calibration results: TAS PT-NC and rTF/95

Whole bloodArtificially depleted plasmaIndividual coumarin plasmaPooled coumarin plasma
The values shown are the ISI derived from the calibration slope b, the CV (%) of the calibration slope, and the number of samples used in the calibration (N). The “Overall” row gives the mean CV(b) and ISI at the 10 centres. The ISI CV% row gives the between centre CV (%) of the ISI. Mean ISI difference (whole blood ISI – lyophilised plasma ISI), corresponding confidence interval (CI) and p value are provided.
*Significant displacement at the 1% level using Tomenson’s test.13 The absolute % INR deviations from the theoretical INR of 2.0 and 4.5, respectively, are given in parentheses. See World Health Organisation guidelines11 for further details; †ISI detected as outlying.
CV, coefficient of variation; ISI, international sensitivity index; rTF/95, human recombinant international reference preparation.
1741.074.4780.923.5 *(10,12)790.864.3 *†(19,14)130.7616.0†
3781.073.4770.982.9 *(8,8)770.962.8131.005.7
5751.262.7790.981.7 *(4,4)770.962.0130.974.3
6791.173.6 *(10,11)790.902.3790.962.4131.024.0
8741.063.8791.042.0781.001.9 *(5,3)130.983.7
10751.084.7800.992.0 *(5,6)780.951.7 *(6,4)130.966.1
Mean ISI difference0.150.170.16
CI(0.09 to 0.21)(0.11 to 0.23)(0.08 to 0.24)
p Value0.00040.00010.001
ISI CV (%)