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Michael

I am responding purely with my UK NEQAS for Glycated Haemoglobins Organiser 'hat' on.  I do not speak for the ACB or any other body.

This issue was amongst those discussed at the ACB West Midlands Scientific Meeting yesterday when Garry John and I gave back-to-back presentations.

I have just done a survey of the UK and Eire participants in my EQA service, as the UK has just gone live with IFCC and DCCT dual reporting for HbA1c, according to the consensus statement published in 2008.  Barth et al. Ann Clin Biochem 2008; 45: 343-344  This statement did not recommend the pursuit of eAG in the UK until more statistically sound and comprehensive (in terms of patient groups) work was undertaken.  This recommendation was repeated in the Dual Reporting guidance leaflet for laboratory professionals published by the ACB / Diabetes UK/ NHS Diabetes Support team  (see http://www.birminghamquality.org.uk/DLopen/52595%20HbA1c%20Lab%20Leaflet.pdf).

The question as to whether any lab was reporting eAG was not directly asked in my survey, but labs were asked to fax a copy of their report.  Only one UK clinical laboratory appears to be reporting eAG.  This news was received with disbelief and concern by the audience at the meeting!

In my humble opinion, the confidence interval of the regression line in the ADAG eAG study allows too wide a range of eAG values for any given HbA1c value for this to be clinically useful, so the question of reference ranges is rather meaningless.  (There are many other criticisms of this relationship which convince me that eAG is a useless parameter!) 

In principle, the separate analysis of glucose and HbA1c by properly standardised, traceable assays, according to evidence-based protocols, is superior to deriving population based parameters that have large uncertainty, and may have no relevance to individual patients, particularly those in groups which are under-represented in the ADAG study.

As more accurate and specific assays come onto the market, which have been released from the albatross of DCCT-alignment around their necks, we may find new clinically useful information about the subtleties of glycation in different patient groups.  Converting HbA1c results to an artificial parameter using a one-size-fits-all approach will not allow this to happen.

With kind regards

Jonathan Middle


On Tue, Jun 30, 2009 at 10:44 PM, PD Dr. Michael Steiner <[log in to unmask]> wrote:
Dear colleagues,

Most probably, some of you have started reporting estimated average glucose
(eAG) concentrations derived from HbA1c according to the ADAG study
formula. The easy part is that calculations will be done by the lab IT
environment. However, when it comes to reference intervals (does this term
apply?) and flagging rules, things are not that easy. Therefore, please
share the eAG concentrations getting a mark or comment (increased or
similar) in your labs.

Thank you very much for sharing practice, thoughts, and opinions.

Best regards,

Mike

****************************************
PD Dr. med. Michael Steiner
[log in to unmask]
****************************************
Medizinisches Labor Rostock
Südring 81, D-18059 Rostock

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