Issues of Reliability and Validity in the Classification and Diagnosis of Schizophrenia
Classification refers to organising and grouping mental disorders together based on
similar symptom sets.
Diagnosis refers to identifying a disorder based on the symptoms that the client
presents with
There are two main diagnostic and classifications systems for mental disorders:
ICD 11
ICD refers to the “International Classification of Disease”. It is a European system,
produced by the WHO (World Health Organisation). The book/system is called ICD 11 as
this is its 11th revision. ICD 11 published in 2019. Older textbooks will refer to ICD 10 etc.
DSM-5-TR
DSM-5-TR refers to the “Diagnostic and Statistical Manual of Mental Disorders”. It is an
American system, produced by the APA (American Psychiatric Association). DSM is in its
5th edition. “TR” refers “to text revision”. These are changes in the words used to describe
disorders without a major reorganisation/new edition.
Both of these systems attempt to classify mental disorders, i.e. they group related
disorders together that share similar symptom sets. In both DSM and ICD schizophrenia is
classified alongside other psychotic disorders. Both systems are also intended to help
clinicians diagnose schizophrenia.
The key questions in this subsection are:
- Is the way schizophrenia is classified by classification and diagnostic systems like
ICD-11 and DSM-5-TR valid (i.e. do these systems describe schizophrenia, its
symptoms and the way it relates to other disorders accurately)?
- Are diagnoses of schizophrenia by clinicians using these systems valid (i.e. do
clinicians using these systems give the correct diagnoses to their clients)?
- Are diagnoses of schizophrenia by clinicians using these systems reliable (i.e. do
they produce consistent diagnoses over time and from clinician to clinician)?
Whilst the two systems (ICD-11 and DSM-5-TR) have different diagnostic criteria, to be
diagnosed as schizophrenic in each of these systems, a client needs to experience a
number of symptoms to a given level of seriousness over a given period of time.
, Problems can occur when clinicians disagree about whether or not a client is clinical or
subclinical:
Clinical: Enough symptoms + they are severe enough to cross the clinical threshold and
receive a formal diagnosis
Subclinical: Has some symptoms but not enough/severely enough to cross clinical
threshold
Non-Clinical: No symptoms
Clinical threshold: The point at which symptoms are severe enough to be given a formal
diagnosis
Key concepts in the classification and diagnosis of schizophreni8a
Diagnostic Whether or not a clinician gives the correct diagnosis, i.e. a client
(criterion) validity actually has schizophrenia and is diagnosed with it.
Diagnostic Whether or not diagnoses of schizophrenia are consistent
reliability
Test-retest Whether or not diagnoses of schizophrenia are consistent over time
reliability
Inter-rater Whether or not diagnoses of schizophrenia are consistent from
reliability clinician to clinician
Kappa score A measurement of inter-rater reliability. It goes from 1 to 0:
1 = perfect consistency, total agreement
0 = no consistency, total disagreement
Co-morbidity When 2 or more mental disorders, e.g. schizophrenia and
depression, occur at the same time
Symptom overlap When different mental disorders have overlapping symptom sets,
i.e. one symptom is a symptom of more than one disorder
Gender bias Occurs when the gender of the client affects the likelihood of
receiving a diagnosis of schizophrenia
Culture bias Occurs when the culture/ethnicity of either the client or the
clinician affects the likelihood of receiving a diagnosis of
schizophrenia
The relationship between reliability and validity is that a diagnosis cannot be valid if it is not
reliable. If two doctors disagree at least one of them is wrong.
Discuss issues of reliability and validity in the classification and/or diagnosis of schizophrenia (16
marks):
A01
Classification and diagnostic systems such as ICD 11 and DSM 5 TR need to be both valid and
Classification refers to organising and grouping mental disorders together based on
similar symptom sets.
Diagnosis refers to identifying a disorder based on the symptoms that the client
presents with
There are two main diagnostic and classifications systems for mental disorders:
ICD 11
ICD refers to the “International Classification of Disease”. It is a European system,
produced by the WHO (World Health Organisation). The book/system is called ICD 11 as
this is its 11th revision. ICD 11 published in 2019. Older textbooks will refer to ICD 10 etc.
DSM-5-TR
DSM-5-TR refers to the “Diagnostic and Statistical Manual of Mental Disorders”. It is an
American system, produced by the APA (American Psychiatric Association). DSM is in its
5th edition. “TR” refers “to text revision”. These are changes in the words used to describe
disorders without a major reorganisation/new edition.
Both of these systems attempt to classify mental disorders, i.e. they group related
disorders together that share similar symptom sets. In both DSM and ICD schizophrenia is
classified alongside other psychotic disorders. Both systems are also intended to help
clinicians diagnose schizophrenia.
The key questions in this subsection are:
- Is the way schizophrenia is classified by classification and diagnostic systems like
ICD-11 and DSM-5-TR valid (i.e. do these systems describe schizophrenia, its
symptoms and the way it relates to other disorders accurately)?
- Are diagnoses of schizophrenia by clinicians using these systems valid (i.e. do
clinicians using these systems give the correct diagnoses to their clients)?
- Are diagnoses of schizophrenia by clinicians using these systems reliable (i.e. do
they produce consistent diagnoses over time and from clinician to clinician)?
Whilst the two systems (ICD-11 and DSM-5-TR) have different diagnostic criteria, to be
diagnosed as schizophrenic in each of these systems, a client needs to experience a
number of symptoms to a given level of seriousness over a given period of time.
, Problems can occur when clinicians disagree about whether or not a client is clinical or
subclinical:
Clinical: Enough symptoms + they are severe enough to cross the clinical threshold and
receive a formal diagnosis
Subclinical: Has some symptoms but not enough/severely enough to cross clinical
threshold
Non-Clinical: No symptoms
Clinical threshold: The point at which symptoms are severe enough to be given a formal
diagnosis
Key concepts in the classification and diagnosis of schizophreni8a
Diagnostic Whether or not a clinician gives the correct diagnosis, i.e. a client
(criterion) validity actually has schizophrenia and is diagnosed with it.
Diagnostic Whether or not diagnoses of schizophrenia are consistent
reliability
Test-retest Whether or not diagnoses of schizophrenia are consistent over time
reliability
Inter-rater Whether or not diagnoses of schizophrenia are consistent from
reliability clinician to clinician
Kappa score A measurement of inter-rater reliability. It goes from 1 to 0:
1 = perfect consistency, total agreement
0 = no consistency, total disagreement
Co-morbidity When 2 or more mental disorders, e.g. schizophrenia and
depression, occur at the same time
Symptom overlap When different mental disorders have overlapping symptom sets,
i.e. one symptom is a symptom of more than one disorder
Gender bias Occurs when the gender of the client affects the likelihood of
receiving a diagnosis of schizophrenia
Culture bias Occurs when the culture/ethnicity of either the client or the
clinician affects the likelihood of receiving a diagnosis of
schizophrenia
The relationship between reliability and validity is that a diagnosis cannot be valid if it is not
reliable. If two doctors disagree at least one of them is wrong.
Discuss issues of reliability and validity in the classification and/or diagnosis of schizophrenia (16
marks):
A01
Classification and diagnostic systems such as ICD 11 and DSM 5 TR need to be both valid and
