------- Forwarded message follows -------
From: Self <[log in to unmask]>
To: Sten Öhman <[log in to unmask]>
Subject: Re: Release criteria
Date sent: Tue, 13 Nov 2001 09:11:41 -0000
In my specialist area (steroids) there has been considerable
activity over at least a decade in preparing reference materials with
target values derived by IDMS under extremely stringent protocols.
These are unprocessed single donations of serum from normal
individuals and patients with steroid concentrations which span the
main range of interest. The materials have been made available
either
'privately' (SysRef - oestradiol, testosterone, progesterone) or by
the IFCC (cortisol).
Whereas a number of companies have acquired these, only a
relatively small proportion have actually used them to re-calibrate
their assay systems and explicitly stated and promoted this fact.
The
take up of the most recent materials (IFCC cortisol) has been
particularly poor. Either the companies perceive that it is more
important (marketing wise) to be comparable with the market leader
(which could be 'wrong') than to be objectively and scientifically
'right', and/or there is little customer pressure for this.
A few years ago I did major exercises in the UK NEQAS schemes
to show the benefit of using IDMS target values to indicate
calibration and specificity problems, but they have had little impact
on the range of bias between methods.
One way to promote the use of reference methods and materials
by manufacturers, is for customer laboratories to make it a
condition of any tendering exercise that they see the regression and
difference plots of the test method vs the IDMS target values for
these special reference panels. When the IVDD comes into force,
the
traceability elements will require that this kind of information is
made available and should be featured in method inserts and
literature.
Such activity should be extended to other analytical systems
where reference methods exist and special panels of reference
materials could be produced. (Steroids are not the only example
here.)
It needs bottom up (from customers) and top down (from
professional bodies, MDA) pressure to make this so, and it will
cost money to initiate and maintain networks of reference
measurement system laboratories and to produce (on an ongoing
basis) panels of reference materials. The key result of all this
should be improved accuracy and comparability of steroid assays.
One of the key players in this activity, and a close colleague, is
Professor Linda Thienpont whose papers on this subject illuminate
both
theory and practice in an exemplary fashion.
See also http://www.ukneqas.org.uk/saf01.htm
I hope this helps.
JGM
On 12 Nov 2001, at 13:44, Sten Öhman wrote:
> This debate seems as a deja vu from many years ago. It is surprising
> that the quality of calibration and reference materials still is a
> problem. The principles of obtaining highly reliable reference
> materials are not new and its practical implications should have
> been solved now.
>
> Obviously it is not.
>
> The demands for a laboratory ackreditated to produce reference
> materials are very high and it needs both a staff of several highly
> qualified (PhD or more) personnell and advanced instruments.
>
> This is more than any hospital or even small and medium-sized
> nations can afford. Establishment of such reference laboratories
> need international cooperation. So what is the IFCC doing? Or all
> other international and/or federal organizations?
>
> Mr Sten Öhman, PhD
>
> Sten Öhman, PhD
> Elfin Lab & Milieuconsult
> P O Box 133
> S-590 70 Ljungsbro
> Sweden
> Tel Nat: 013-368940 Int: +46 13 368940
> Fax Nat: 013-368941 Int: +46 13 368941
> [log in to unmask]
------- End of forwarded message -------
Jonathan Middle, UK NEQAS Birmingham
tel 0121 414 7300 fax 0121 414 1179
The content of this message is intended only for the above addressee(s).
The opinions expressed are mine alone and do not necessarily represent
those of UK NEQAS Birmingham or the UK NEQAS Organisation
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