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34
| 2 | 2005
Klinisk Biokemi i Norden
Hemochron® Jr. Signature Whole Blood
Microcoagulation Systems
Summary of an evaluation organised by SKUP
Report SKUP/2004/33
Esther Jensen, SKUP Esther.Jensen@ouh.fyns-amt.dk
The Norwegian supplier Medimport AS ordered
a SKUP evaluation of the Hemochron® Jr.
Signature Whole Blood Microcoagulation Systems
(Hemochron) manufactured by ITC US. Hemochron
is intended for measurement of Prothrombine Time
(PT) in the primary health care. The PT analysis
is used for monitoring of patients in vitamin K
antagonist treatment to prevent thrombosis.
The measurement principle of the Hemochron
instrument is whole blood clot time measured after
optical detection of the change in movement of
the mixture in the cuvette. The clotting time is
defined as the time from the mixing of blood and
reagents until the blood movements of the mixture
decreases below a predetermined rate. The system is
based on the Quick method for Prothrombine Time
(PT), (factor II, V, VII, X and fibrinogen). From the
whole blood measurement the equivalent plasma
PT is calculated based on regression analyses per-
formed across multiple centres. The result is given
in the scale INR (International Normalised Ratio).
The International Sensitivity Index (ISI) is approxi-
mately 1.0. A high number in the INR-result reflects
Analytical quality
Type of sample N
CV % (within) Bias (%)
Total Error,
(95 % CI)
At 3 or 2 levels
fulfilment of goal
Quality goals (SKUP)
≤
5
> 95% < ±20% deviation
Quality goals (Denmark1)
≤
5
≤
± 6%
Hospital laboratory
Venous
100 8.5 (7.4 - 9.8)
1.5, -2.2, -10.2
84.0 %
Capillary
46 7.9 (6.5 – 9.9)
1.5, -14.5
73.9 %
Primary care
Venous
40 7.4 (6.1 – 9.4)
39 7.7 (6.3 – 9.8)
Capillary
40 9.1 (7.5 – 11.7)
Figure 1. Total Error. Hemochron
The diagram shows the deviations of
the Hemochron results with venous and
capillary samples. X-axis = mean of
reference method duplicate results and
Y-axis = ((first Hemochron result– mean
of reference method, duplicate results)/
mean of reference method, duplicate
results) x 100. Acceptance limits for
Hemochron is ± 20 %. 95 % of the
results should be within the acceptance
limits. It is considered as acceptable
that 1 % of the results deviate > ±
25 % from the reference laboratory.
Acceptance limits for the hospital labo-
ratory is ± 9 %. 95 % of the results
should be within the acceptance limits.
(Fortsætter side 34)
