There is a problem with the traditional concept of 'diagnosis'.
Osler's teaching that we should try to deduce the underlying aberrant
physiology from clinical (or in our case laboratory) observations appears to
have led to labelling that, in turn, has been taken to imply pathological
cause.
Often loose use of language has then been taken to imply outcomes that may
or may not be justified. Particularly misleading terms include
'carcinoma-in-situ' where features such as mitotic figures lead to a term
that is often taken to imply potential invasiveness.
When we judge the effectiveness of diagnostic flow charts we are comparing
the diagnostic conclusion of the relatively unskilled with the diagnostic
conclusion of those formulating the chart in the first place. Not
surprisingly given this judgemental bias those using the flow charts do
well.
Flow charts are often generalised. As such they fail to make allowance for
the simple fact that each and every patient can be assigned to one or more
sets or groups according to what is already known (sex, age, ethnicity prior
clinical or laboratory findings etc). The behaviour of subsequent data in
directing decisions can be set dependent.
Similar objections can be raised to many 'expert systems'. Only rarely do
such systems make any attempt to divide patient into prior-data sets except
where that data is known to correlate with diagnostic assignment and that
'gold standard' assignment is no more than the opinion of an expert panel.
Trevor Tickner
Norwich
> -----Original Message-----
> From: Mike Collins [SMTP:[log in to unmask]]
> Sent: 12 December 2001 14:36
> To: [log in to unmask]
> Subject: Re: a challenge for interpretative comments ....
>
> As an MLSO I am not involved with interpretative comments
> but I would be interested to know how duty biochemists
> perform in competition with expert systems. If a fraction of the
> effort which has been applied to chess programs had been
> used in clinical biochemistry, haematology and immunology
> expert systems I suspect that most clinical validation would
> be obsolete.
> I recall a report that barefoot doctors in Tanzania using
> flowcharts were as accurate as (but slower than) experienced
> consultants in the diagnosis of the causes of acute abdominal
> pain.
> Perhaps the ACB should have an annual "Comments
> Olympics" at Focus with biochemists and software as
> contestants.
>
> Mike Collins
> Mike Collins MLSO3
> Clinical Biochemistry & Immunology
> The General Infirmary at Leeds,
> Old Medical School, Thoresby Place
> Leeds LS1 3EX, UK
> [log in to unmask]
> [log in to unmask]
> 44 (0) 113 392 2915
> http://www.leedsteachinghospitals.com
> The opinions expressed here are my own.
> My colleagues and employers may not agree with them.
>
>
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