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Lot
to lot reproducibility
When employing any HEMOCHRON® Jr PT assay, it is not possible to alter either
the mean normal PT nor the reagent ISI. This places the onus on ITC, as the manufacturer
of these tests, to ensure the consistency of the results obtained between cuvette
lots. This has been accomplished through the implementation of substantial procedures
for the characterization of the thromboplastin employed as well as extensive
Quality Control testing of each lot of cuvettes prior to release for sale.
The
procedures employed in the characterization of the thromboplastin
preparations employed have been comprehensively reviewed by the US
FDA as part of their review of the PT assays. These protocols ensure
that each batch of thromboplastin used to manufacture cuvettes retains
an ISI close to 1.0. This ISI assignment has been independently challenged
and verified by Gosselin and colleagues (Thromb Haemostas, 2000,
83: 698 – 703).
Prior to release for sale, each lot of cuvettes is
challenged with defined substrates in the normal (INR < 1.5), therapeutic
(INR between 2.0 and 3.0) and supratherapeutic (INR between 4.0 and
5.0) ranges. The graph below shows the mean values obtained during
this testing for a sequence of 50 lots of cuvettes spanning two independent
thromboplastin preparations.
The percent of lots displaying each value is plotted against this mean INR. Clearly, there is very little lot to lot variability observed during this testing. Between lot comparisons of the INR results at each level show neither clinical nor statistical differences between any of the lots examined.
Please click here for comparisons chart
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