Don't forget that when you try and compare NPT with lab tests you are not
actually comparing like with like. The capillary sample you measure with NPT
is 'allowed' to be as much as +/- 0.5 compared with the venous sample which
the lab will test. The variability doesn't end there - labs using a variety
of test gear report a similar disparity I results from the same samples in
different test machines.
It's not this difference which causes patients to be suddenly unstable -
it's the element of doubt which creeps in when trying to decide which result
is 'correct'. The answer is to stick with one set of results as far as you
are able, and not switch from the NPT result to lab result (or vice versa)
at each test, just because you want to err on the side of caution.
Robert
> -----Original Message-----
> From: GP-UK [mailto:[log in to unmask]] On Behalf Of Stephen
> Sent: 01 September 2004 22:40
> To: [log in to unmask]
> Subject: Re: Anticoagulation Monitoring
>
> Paul Bromley wrote:
>
> > I've never really been heavily involved in this before, but I've just
moved
> > practices and have been asked my views on this. Has anyone any advice on
> > whether worthwhile, software testing equipment etc. At our last practice
we
> > had a visit from the haematology department and I think I recall them
> > mentioning that the cheaper kits were inaccurate and expensive to run
with
> > strips. I know that Robert Treharne Jones here is heavily involved with
> > INRStar. Any help appreciated. What are the costs of the monitoring
> > equipment? I suspect that there is very little if any revenue in this -
> > especially the first year. Small practice - around 60 on ACs at the
moment.
>
> Having started this a few months ago we're rather regretting it although
> perhaps things will settle down. The machine (machine and strips
> provided by the PCT) we have in the surgery consistently reports INR
> levels of 0.5-1 points below the hospital lab reading on the same
> sample, resulting in patients who were previously stable for months
> having dosage changes and weekly recalls. INRStar (we are about to buy)
> is irritating and counter-intuitive but enables the nurse to run most of
> the process.
>
> I too will be interested to hear others' views.
>
> --
> Regards,
>
> Stephen
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