Hi Sam,
This case is I believe actually a measure of accuracy of a result.

In my pathology system, I deal with it by having a separate attribute on 
quantity
It takes values such as >, <, >=, <=, ~   
(~ => approximately, I => Inaccurate)

the value "I" may be used for instance when an analyser returns a potassium 
value
which on subsequent examination of the blood is shown to be erroneously 
high due to haemolysis. This is usually accompanied by some text which
is displayed instead of the numeric value e.g. HAEM but the underlying
numeric value needs to be stored anyway as well.

This of course makes the logic for deciding whether a result is within a normal 
range
more interesting and graphing routines etc need to take this flag into account.

I don't feel strongly whether you deal with this as part of the quantity 
datatype or have a new
datatype inheriting from quantity.

Regards
Vince

Dr Vincent McCauley MB BS, Ph.D
McCauley Software Pty Ltd


----- Original Message ----- 
  From: Sam Heard 
  To: Heath Frankel 
  Cc: Tom Beale ; Openehr-Technical 
  Sent: Wednesday, March 01, 2006 12:41 PM
  Subject: Re: Pathology numeric values not supported in DV_Quantity


  Hi everyone,

  We want to report an issue that has arisen in data processing in Australia.

  The issue is the somewhat random ability of systems to report a >xx or <yy 
range where a quantity is expected - there are still units and still a normal 
range. This is common with TSH and GFR - but can turn up in unexpected 
instances - e.g. we had a baby with a HCO3 of <5 mmol/L. This can be dealt with 
at present by substituting an interval - but it is a bit wierd as there is 
still a normal range - it kind of works as there is only a lower or upper value 
of the interval and so this single quantity can carry the normal range.

  The point is that it is really a point measurement that is outside the range 
of the measuring device. Also, it means that we will have to have archetypes 
that allow multiple datatypes for all quantities that could conceivably be 
measured in this way.

  The alternative is to consider a DV_QUANTITY_RANGE that inherits from 
DV_QUANTITY - it still has only one value - but now it has the ability to set 
this as the upper or lower value - and also whether this number is included or 
not.

  The advantage is that there would still be a number to graph and this data 
type could always be substituted for a DV_QUANTITY (ie without archetyping).

  I wonder what others think.

  Cheers, Sam

  -- 

  Dr. Sam Heard
  MBBS, FRACGP, MRCGP, DRCOG, FACHI
  CEO and Clinical Director
  Ocean Informatics Pty. Ltd.
  Adjunct Professor, Health Informatics, Central Queensland University
  Senior Visiting Research Fellow, CHIME, University College London
  Chair, Standards Australia, EHR Working Group (IT14-9-2)
  Ph: +61 (0)4 1783 8808
  Fx: +61 (0)8 8948 0215



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