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..

“Discuss the issues associated with classification and/or diagnosis of Schizophrenia” (8 + 16 marks)

Exam trigger word

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

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, working-class or female clients.”

Inter-rater reliability – do psychiatrists agree?

• 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!

I wonder what the other bloke thinks?

Inter-rater reliability – do psychiatrists agree?

• 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!

I really hope I agree with that other bloke!

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 evidencechallenging

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.”

AimThe 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

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 LabellingOnce people are ‘labelled’ as having a disorder .. all of their behaviour can be interpreted as being caused by the disorder.

ClipRosenhan 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 mis-diagnosis

A03 Rosenhan - robust procedure + mixed sample

IDA Argument evaluation – differential diagnosis/ dual

diagnosis/ cultural differences