European Concerted Action on Anticoagulation (ECAA). An assessment of lyophilised plasmas for ISI calibration of CoaguChek and TAS whole blood prothrombin time monitors.
OBJECTIVE
The recommended method for the international sensitivity index (ISI) calibration of whole blood point of care testing (POCT) prothrombin time (PT) systems was originally described by Tripodi et al in 1993 but is too complex and demanding. The present European Concerted Action on Anticoagulation (ECAA) study aimed to assess the reliability of simpler ISI calibration using lyophilised plasma samples.


METHODS
ISI calibrations using three different types of ECAA lyophilised plasma samples (artificially depleted, individual, and pooled coumarin) were compared with whole blood calibrations on CoaguChek Mini and TAS PT-NC POCT monitors at 10 centres.


RESULTS
With CoaguChek Mini systems, lyophilised coumarin plasma samples (both single donation and pooled) gave ISI and international normalised ratio (INR) values comparable to whole blood. With artificially depleted plasma, ISI and INR values were too high. With TAS PT-NC systems, all three types of lyophilised plasma samples gave inaccurate ISI and unreliable INR results, similar to previous ECAA findings with fresh plasma calibrations.


CONCLUSIONS
With CoaguChek Mini systems, ISI calibration can be simplified by the use of ECAA lyophilised plasma samples from coumarin treated patients. Further study is needed to devise a simpler calibration method for the TAS PT-NC system.
Poller
L
L
ECAA Central Facility, School of Biological Sciences, The University of Manchester, Manchester M13 9PT, UK. ecaa@man.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
D000328:Adult; D002138:Calibration; D003374:Coumarins; D005060:Europe; D005612:Freeze Drying; D006801:Humans; D019095:Point-of-Care Systems; D011517:Prothrombin Time; D011786:Quality Control; D011934:Reagent Strips; D012016:Reference Values; D015203:Reproducibility of Results
D003374:Coumarins; D011934:Reagent Strips; C030123:coumarin