Download 4. Reliability of diagnosis 2013

Classification and
diagnosis of schizophrenia
• There are a number of criticisms associated
with the diagnosis of Schizophrenia.
• These involve the concepts of validity and
reliability- two terms that you are already
familiar with.
Remember ..
Potential exam question..
Exam trigger word
“Discuss the issues associated with classification
and/or diagnosis of Schizophrenia”
(8 + 16 marks)
Issues of reliability and
validity
RELIABILITY
How reliable is a
diagnosis of
schizophrenia?


Reliability is how far the classification system
produces that same diagnosis for a particular set
of symptoms. In order for a classification system to
be reliable the same diagnosis should be given
each time it is used. This means that different
clinicians should reach the same diagnosis.
Classification system = ICD DSM ..
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.
Issue of reliability continued


Schizophrenia diagnosis may be affected by
cultural bias. For example, Harrison at al (1984)
showed that there was an over-diagnosis of
schizophrenia in West Indian psychiatric patients in
Bristol.
No research has found any cause for this, so its
suggests that the symptoms of ethnic minority
patients are interpreted differently.
Issue of reliability continued


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This questions the reliability of the diagnosis of
schizophrenia – it suggests that patients can display
the same symptoms but receive different diagnosis
because of their ethnic background.
For example;
Fernando (1988); black patients more likely to be
treated using ECT (electroconvulsive therapy) and
major tranquillizers than white patients.
Issue of reliability continued


Simon et al in Davison et al (2004); in a hospital
based study found that African-Americans were
over diagnosed with schizophrenia and under
diagnosed with mood disorder (Depression).
Winter (1999) found that women were more likely
to be diagnosed as psychiatrically ill compared to
men.
Issue of reliability continued

Winter (1999) also provides evidence for why
working class patients are more likely to be
diagnosed as mentally ill compared to middle class
patients: “general practitioners and psychiatrists
….are predominately white, middle- class and male
[they] may be biased …or insufficiently sensitive to
the cultural and social situations of black, workingclass or female clients.”
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!
What psychiatrists don’t understand
• It is tempting to label a person as a
sufferer of schizophrenia, 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.
The NHS is a wonderful thing!
• 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
How valid is a diagnosis of
schizophrenia?

Validity is whether the classification system is
actually measuring what it aims to measure. There
are three types of validity..
Issue of validity continued



Descriptive validity – how similar individuals
diagnosed with schizophrenia are.
Aetiological validity – how similar the cause of
schizophrenia is for each person (sufferer).
Predictive validity – how useful the diagnostic
categories of schizophrenia are for predicting the
right treatment for each person (sufferer).
Research evidence
challenging
the
Predictive validity
of diagnosis
Rosenhan’s ‘sane in insane places’ study
(1973)
• found that psychiatric
staff cannot always
distinguish sanity from
insanity.
• Any diagnostic method
that makes such errors
may be challenged as
having
low reliability & low
predictive validity.
Rosenhan (1973) “On being sane in
insane places.”
Aim
The aim of this study was to test the hypothesis that psychiatrists
cannot reliably tell the difference between people who are sane
and those who are insane.
Procedure
•The first part of the study involved eight sane people (a psychology
graduate student in his 20s, three psychologists, a paediatrician, a
psychiatrist, a painter, and a 'housewife') attempting to gain admission to
12 different hospitals, in five different states in the USA.
•There were three women and five men.
•These pseudo-patients telephoned the hospital for an appointment, and
arrived at the admissions office complaining that they had been hearing
voices.
•They said the voice, which was unfamiliar and the same sex as
themselves, was often unclear but it said 'empty', 'hollow', 'thud'.
Results
•None of the pseudo patients was detected and all but one were admitted
with a diagnosis of schizophrenia and were eventually discharged with a
diagnosis of 'schizophrenia in remission'
•This diagnosis was made without one clear symptom of this disorder. They
remained in hospital for 7 to 52 days (average 19 days), Visitors to the
pseudo patients observed ‘no serious behavioural consequences'.
•Although they were not detected by the staff, many of the other patients
suspected their sanity (35 out of the 118 patients voiced their suspicions).
Some patients voiced their suspicions very vigorously for example ‘You’re
not crazy. You’re a journalist, or a professor. You’re checking up on the
hospital’
Criticising the validity of diagnosis
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Rosenhan (1973) conducted a study where people
with no real mental health problem got themselves
admitted into a psychiatric unit
By saying they heard voices – they became pseudo
patients
Once they were admitted they behaved ‘normally’.
However their behaviour was still seen as a
symptom of their disorder by the staff of the unit.
For example one pseudo patient who wrote in a
diary was recorded as displaying abnormal ‘writing
behaviour’.
Issue of validity continued
Danger of Labelling
 Once people are
‘labelled’ as having a
disorder .. all of their
behaviour can be
interpreted as being
caused by the
disorder.
Clip
Rosenhan Study
Essay question


Discuss the issues
associated with
classification and/or
diagnosis of
Schizophrenia
(8+16marks)
Remember that the
term issues refers to
validity and
reliability.
Sample PLAN
A01 Intro- issue = questioning the validity/reliability of diagnosis of
schizophrenia..
 Describe issues of validity (three types) + reliability
 Define Mis-diagnosis
A02 Evaluation
Criticism – Cultural Biases in diagnosis- Fernando/Harrison/Winter
Criticism – inter-rater reliability - Beck
Criticism – Predictive validity - Rosenhan study as example of misdiagnosis
A03 Rosenhan - robust procedure + mixed sample
IDA Argument evaluation – differential diagnosis/ dual
diagnosis/ cultural differences