During the last decade quality management systems
has gained an increased interest throughout laboratory medicine.
This has called for harmonisation of criteria for accreditation and
for the wider concept of total quality management. Existing
standards like the ISO 9000 series, ISO Guide 25 and the EN 45000
series do not fulfill the need for a comprehensive standard that
that goes beyond the technical analytical aspects. The time has now
come to evaluate our laboratories using standards that not only
focus on the quality of the analytical performance but also on
patient related aspects of our activities. A new standard, ISO/FDIS
15189 that is harmonized with the ISO 9001-2000 is under
preparation and is likely to be endorsed by the standards
organisations during year 2001. This standard is substantially more
focused on pre-and post analytical aspects and patient outcome
criteria than previous standards.
An example on the need for modernisation of
existing standards is the fact that the Clinical Pathology
Accreditation (UK) Ltd have published new " Standards for the
Medical Laboratory " , January 2001 (
http://www.cpa-uk.co.uk/ ). This document is a
national standard with cross references to ISO/FDIS 15189,
ISO/IEC17024/2000, ISO/DIS 9001(E) and EC4 Essential Criteria. The
EC4 Essential Criteria is yet another example.
A number of points of interest in this respect are
discussed in this issue of eJIFCC.
The Swedish Society for Clinical Chemistry has,
through its expert group, produced a proposal for a protocol, which
enhances the clinical and medical aspects on laboratory work. Some
of the items will be found in the ISO 15189 but it was originally
written to complement the EN 45001.
All measurements harbor an inherent uncertainty.
The ISO definition of uncertainty in measurement is: "parameter,
associated with result of measurement that characterises the
dispersion of the values that could be reasonably attributed to the
measurand". As this definition is rather difficult to live up to in
practical laboratory workAnders Kallnerexpands and explains the
definition in this issue ofeJIFCC.A result should not only be
described in terms of reproducibility but also how close it is to
an assumed "true value". Since we do not know the "true value" we
have to work with "assigned values" or what is also called
"conventional true value". It is, however, no easy task to
determine the " conventional true value " . Should it be done
through the creation of " mentor/reference laboratories " or can
one use the values obtained from sufficiently large groups in
external quality assessment programs?Biaswill then be the
difference between many measurements of the same quantity and the
assigned value. The statistic trueness will describe the systematic
error. The concept ofaccuracyincludes both random and systematic
errors and is also often referred to astotal error.Should bias be
included in the so calledtotal error?To me that is not absolutely
obvious and the main reason for this is the difficulty in defining
the " true value " and consequently also the uncertainty of the
bias.
After a period of time during which the emphasis
has been on the analytical technical/quality of laboratory medicine
measurements the time has now come to develop recommendations and
standards for the pre- and postanalytical phases in order to come
closer to total quality management.Narayanan and Guderhighlight the
importance of knowledge of the preanalytical variables and their
influence on the quality of laboratory results. The German Society
for Clinical Chemistry and the German Society for Laboratory
Medicine have been very active in this field and published their
recommendations regarding preanalytical variables as late as last
year (1). The authors of the present article anticipate that with
the awareness and introduction of strategies to recognise
preanalytical errors the goal of achieving total laboratory quality
is finally within our grasp.
In the previous issue of this journal we focused on
POCT instruments and methodology. The use of POCT has increased
enormously during the last decade and will in all probability
continue to do so. This has brought forward the need for good
quality assessment programs for this type of tests.
Callum G Fraserdiscusses "Optimal analytical
performance for POCT" the hierarchy of strategies to set quality
specifications. The hierarchy is the one proposed by him and
Hyltoft Pedersen (2) and later approved by expert professionals
(3). His conclusion is that there is no reason why POCT analyses
and analyses performed at other sites should be judged by different
standards. At the top of the hierarchy is assessment of the effect
of analytical performance on specific clinical decision making. The
discussion on how positive and negative bias can effect the cost of
health care in the short run and in the long run and the
effectiveness of treatment is very illustrative. Even if it is to
be preferred to use strategies at the top of the hierarchy it is
argued that those further down are better than none.
It is high time to focus on the quality assessment
of the analytical performance of POCT instruments and methods and
not only on their speed of analysis. For instance, when will we get
a uniform calibration system for POCT glucose analysers?
1. Recommendations of the working group on
preanalytical variables of the German Society for Clinical
Chemistry and the German Society for Laboratory Medicine.
Darmstadt, Germany: GIT, 2000
2. Fraser CG, Hyltoft-Petersen P. Analytical
performance characteristics should be judged against objective
quality specifications. Clin Chem 1999;45:321-3
3. Hyltoft-Petersen P, Fraser CG, Kallner A,
Kenny D, eds. Strategies to set global analytical quality
specifications in laboratory medicine. Scand J Clin Lab Invest
1999;59:475-585