I think what Stephen Frost is implying here is that  IMA 
concentration measurements  essentially constitute  qualitative 
tests, of the sheep versus goats variety. These obviously play a 
large and valuable part in medicine , such as in virology (eg to 
identify subjects infected with HIV, various hepatitis viruses, etc). 
Certain indicators of (quantitative)  assay performance are generally 
less crucial in these circumstances, though  adequate  assay 
sensitivity (ie  precision with which the assay measures zero 
analyte)  and specificity (both in the analytical sense) are clearly 
important. So even in such circumstances the analyst needs to 
understand what he/she  is doing and can't afford to be sloppy.

Roger Ekins


>Thanks Ian,
>
>I have no direct experience of IMA so perhaps should keep quiet, but it
>occurs to me that if your data is correct, that presumably means the test
>can be used to exclude roughly 50% of patients with TnT negative chest pain
>from attending follow-up clinics. I am sure some managers will find the test
>very helpful with their budgets. IMA could become the next great demand
>management tool providing considerable cost and time saving to clinicians.
>
>Even better I think. If the actual test results themselves don't matter,
>standardisation, imprecision and inaccuracy aren't important. Though I am
>sure we should still do our best to minimise them! Opinions welcome on that
>point.
>
>(You could of course adjust the 50% figure to any other percentage just by
>changing the cut-off value.)
>
>It sounds great! Kudos points to any committees that can help generate
>demand for IMA.
>
>Regards
>Steve
>
>ps The views expressed are entirely my own and are unlikely to have any
>scientific validity.
>
>-----Original Message-----
>From: Ian Godber [mailto:[log in to unmask]]
>Sent: 21 November 2006 15:56
>To: [log in to unmask]
>Subject: Re: IMA - why are we measuring it?
>
>Further to Sean's email, amongst those who've looked at IMA, what is the
>general consensus on it's clinical utility??
>
>In 2004 we looked at it on the Beckman LX20 in patients presenting <12
>hours following onset of chest pain (n=160) to see if it distinguished
>patients later classified with chest pain due to either ischaemic (n=41) or
>non-ischaemic causes (n=86).
>
>All our patients with chest pain had an ECG, and were tested for IMA and
>cTnT on admission. We found no significant difference was seen between the
>patients with suggestive ischaemia and those with non-cardiac causes
>(p=0.5092).
>
>The only difference we saw was between the patients with TnT positive
>cardiac chest pain and 'normal' individuals. This difference can already be
>established using TnT. A linear relationship was seen between albumin and
>IMA, where a low albumin correlated to a raised IMA result, thus
>complicating the interpretation of IMA and requires further work,
>a link between an APR and IMA was ruled out though.
>
>This was presented as a poster at EuroMedLab in Glasgow (Todd et all, Clin
>Chem Acta 355(s): p105). It'd be interested to see what others have found
>and if anyone's using it in clinical practice.
>
>Ian
>
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community working in clinical biochemistry.
Please note, archived messages are public and can be viewed
via the internet. Views expressed are those of the individual and
they are responsible for all message content.
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