Download Reliability and Validity of diagnosis

DSM- IV
• The Diagnostic and Statistical
Manual of Mental Disorder
(Edition 4), was last published in
1994.
• The DSM is produced by the
American Psychiatric Association.
• It is the most widely used
diagnostic tool in psychiatric
institutions around the world.
ICD - 10
• There is also the
International
Statistical
Classification of
Diseases (known as
ICD).
• It is produced by the
World Health
Organisation (WHO)
and is currently in it’s
10th edition.
Reliability and validity of DSM-IV
and ICD-10
• Diagnosing a mental disorder is almost always
done using the DSM-IV and the ICD-10.
• However, there is a risk of using this professional
jargon. (Wording in the manuals is written for
specialists to understand, not laymen).
• The main issues surrounding the diagnosis of
mental disorders centre on the reliability and
validity of the diagnoses.
Inter-rater reliability – do
psychiatrists agree? I wonder what
• Beck et al (1961)
looked at the inter-rater
reliability between 2
psychiatrists when
considering the cases
of 154 patients.
• The reliability was
only 54% - meaning
they only agreed on a
diagnoses for 54% of
the 154 patients!
the other bloke
thinks?
Inter-rater reliability – do
psychiatrists agree?
I really hope I
agree with that
other bloke!
• A true diagnosis cannot
be made until a patient is
clinically interviewed.
• Psychiatrists are relying
on retrospective data,
given by a person whose
ability to recall much
relevant information is
unpredictable.
• Some may be
exaggerating the truth –
or blatantly lying!
Reliability of DSM and ICD
» It was originally hoped that the use of
diagnostic tools could provide a
standardised method of recognising
mental disorders.
• However clear the diagnostic tool, the
behaviour of an individual is always open to
some interpretation. The process is subjective.
• The most famous study testing the
subjectivity, reliability and validity of
diagnostic tools was Rosenhan et al (1972).
On Being Sane in Insane Places
• Rosenhan recruited 8 people (he worked with them or
knew thm in some capacity).
• Each of the 8 people went to a psychiatric hospital
and reported only 1 symptom. That a voice said
only single words, like “thud”, “empty” or “hollow”.
• When admitted, they began to act “normally”. All
were diagnosed with suffering from schizophrenia
(apart from 1).
• The individuals stayed in the institutions for
between 7 to 52 days.
On being sane… follow up
• Rosenhan told the institutions about his results,
and warned the hospital that they could expect other
individuals to try & get themselves admitted.
• 41 patients were suspected of being fakes, and 19 of
these individuals had been diagnosed by 2
members of staff.
• In fact, Rosenhan sent no-one at all!
• A good film to watch: One Flew Over the Cuckoo’s
Nest (is Jack Nicholson’s character mentally ill? Is
he mad, bad or sad? You decide!
What psychiatrists don’t understand
• It is tempting to label a person as a
sufferer of depression, without
really knowing the extent to which
they are suffering.
• The beliefs and biases of some
might mean the unnecessary
labelling of millions of people as
sufferers of a mental disorder.
• Sometimes a disorder must reach a
particular level of severity before it
can be recognised with confidence
as a mental health issue.
Who pays for medical care?
How does this affect treatment?
• There is limited time and resources available of many
professionals working in the National Health Service.
• Diagnoses can be made by professionals that are rushed,
and preoccupied with only admitting the most serious cases
in order to safeguard the resources of the institution they are
working for.
Meehl (1977)
• Suggests that mental health professionals
should be able to count on the diagnostic
tools if they:
– Paid close attention to medical records
– Were serious about the process of diagnosis
– Took account of the very thorough descriptions
presented by the major classificatory systems
– Considered all the evidence presented to them.
Validity of diagnosis
• Does the system of classification and diagnosis
reflect the true nature of the problems the patient is
suffering; the prognosis (the course that the
disorder is expected to take); and how great a
positive effect the proposed treatment will actually
have.
• Many individuals do not neatly fit into categories
that have been created. Instead of acknowledging
this, clinicians tend to diagnose 2 separate
disorders.
Labelling
• Someone who has suffered a
mental disorder has to disclose that
information in situations such as
job interviews, or they could face
formal action.
• Unlike influenza, the label of
‘bipolar disorder’ or ‘depression’
stay with a person.
• Schizophrenics risk carrying the
stigma of their condition for the
rest of their lives.
Cultural Relativism
• Davison & Neale (1994) explain that in
some Asian cultures, a person
experiencing some emotional turmoil is
praised & rewarded if they show no
expression of their emotions.
• In certain Arabic cultures however, the
outpouring of public emotion is
understood and often encouraged.
• Without this knowledge, an individual
displaying overt emotional behaviour
may be regarded as abnormal, when it
fact it is not.
Language difficulties
• The clinician might not speak the same language
as the person they are attempting to diagnose.
• Certain things can be ‘lost in translation’
• This could lead to inappropriate treatment or no
treatment at all.
A final thought…
• A person cannot be diagnosed with the
condition if an existing mood disorder has been
diagnosed in the past or if the person is
suffering from this at present.
• It could also be the case that such symptoms are
brought about as a result of another medical
condition or the abuse of illegal drugs or other
medications.
How to revise this topic:
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DSM IV – written by APA – last published in 1994.
ICD – 10 – written by WHO.
Reliability – Beck (1961) – 54% agreement
Rosenhan study – subjectivity
Issues with severity – unnecessary labelling.
Validity – p’s don’t fit into categories
Labelling/Stigma
Cultural relativism – Davison & Neale (1994)