Klinisk Biokemi i Norden Nr 2, vol. 19, 2007 - page 42-43

42
| 2 | 2007
Klinisk Biokemi i Norden
(Fortsætter side 44)
Background for the evaluation
The Precision-system from Abbott is designed for
glucose self-measurements by diabetics. The Precision
Xtra Plus (G3c) is the third generation test strip from
Abbott with “True Measure Technology”. In this
evaluation the test strip was used together with the
Precision Xceed meter. The G3c test strip was laun-
ched onto the Norwegian market in February 2007.
In order to give reimbursement for glucose test
strips in Norway, The National Social Insurance
Office instructs the companies to carry out an eva-
luation that includes a user-evaluation among dia-
betics. The results in the evaluation must meet the
quality goals recommended in ISO 15197.
The user-evaluation of Precision Xtra Plus test
strip (G3c) was organised by SKUP during the winter
of 2005/2006. A supplementary user-evaluation was
done during the summer of 2006.
The aim of the evaluation
The aim of the evaluation was to
– reflect the analytical quality under standardised
and optimal conditions, performed by trained
laboratory staff
– reflect the analytical quality by the users
– compare the analytical quality among diabetics
with and without training
– compare the analytical quality among diabetics
before and after three weeks of practise
– check the variation between three lots of test
strips
– examine if hematocrit interferes with the
measurements
– evaluate user-friendliness and the user-manual
Materials and methods
The evaluation of Precision Xtra plus test strip has
been performed twice and includes a complete user-
evaluation and a supplementary user-evaluation.
Precision Xtra Plus strips are calibrated to the
Precision Xtra Plus (G3c) glucose
Grete Monsen, SKUP (grete.monsen@noklus.no)
Summary of an evaluation organised by SKUP
Report SKUP/2006/49
The complete report, with comments from Abbott, is available at www.skup.nu
Yellow Springs Instruments (YSI), while the desig-
nated comparison method is a hexokinase based
method. According to Abbott Diabetes Care (ADC)
the YSI method is known to report lower plasma
glucose results than hexokinase based methods. The
difference is estimated to be between 4 and 8 %, or
even 10 %.
In the first user-evaluation SKUP pointed out a
negative bias between 8 and 18 % for Precision
Xtra Plus compared to the comparison method.
According to the initial response from ADC regar-
ding the preliminary report, the three lots of
test strips that were used in the evaluation were
amongst the very first batches manufactured, and
a drop in the accuracy had been observed in clini-
cal studies as part of ADC’s standard Post Market
Surveillance Programme. The reported negative bias
was reduced by a calibration adjustment applied in
manufacturing all subsequent lots. Abbott wanted
to have a supplementary user-evaluation performed
with three lots of test strips with improved analy-
tical quality.
Analytical quality goals
ISO 15197 recommend the following minimum
acceptable accuracy requirement:
Ninety-five percent of the individual glucose
results shall fall within ± 0,83 mmol/L of the results
of the comparison method at glucose concentrations
< 4,2 mmol/L and within ± 20 % at glucose con-
centrations
4,2 mmol/L.
This is a quality goal for measurements made by
trained laboratory staff. Ideally, the same qua-
lity requirements should apply to measurements
performed by the diabetics. Previous investiga-
tions under the direction of the NOKLUS-project
“Diabetes-Self-measurements” showed that few of
the self-monitoring glucose meters tested at the
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