Diagnosis and classification- validity and reliability Flashcards
Define classification
Refers to our ability to identify a disorder, as different to all other disorders, based upon the symptoms it presents
Define diagnosis if schizophrenia
refers to our ability to
reliably (consistently) diagnose schizophrenia as schizophrenia.
What are the two major classification systems
- World Health Organisation’s International Classification of Disease (ICD-10)
- American Psychiatric Association’s Diagnostic and Statistical Manual edition 5 (DSM-5)
What are positive symptoms?
Positive symptoms are additional experiences beyond those of ordinary existence. They include hallucinations and delusions.
What are negative symptoms?
Negative symptoms involve the loss of usual abilities and
experiences. Examples include speech poverty and avolition.
What is the diagnostic criteria of schizophrenia in the DSM-5?
- DSM states that signs of disturbance should be apparent for at least 6 months
- At least one positive symptom must be present for diagnosis
What is the diagnostic criteria of schizophrenia in the ICD-10?
- ICD requires the signs to be apparent for one month.
- Two or more negative symptoms are sufficient under ICD.
What are hallucinations ( positive symptom)
Unusual sensory experiences.
when you think that you perceive something that does not exist in reality: auditory and visual.
Some hallucinations are related to events in the environment, some are random
What are delusions (positive symptom)
Also known as paranoia, delusions are irrational beliefs.
1. Delusion of control: a belief that other people are controlling our thoughts
2.Nihilistic delusion that things don’t exist
3. Delusions of grandeur: patient believes he or she has special powers, talents, or abilities. E.g. believe they are an important historical, political or religious figure, such as Jesus.
4. Persecutory delusions: when a person believes he or she is being tormented, followed, tricked, spied on, or ridiculed E.g. government or aliens after them.
What are delusions (positive symptom)
Also known as paranoia, delusions are irrational beliefs.
1. Delusion of control a belief that other people are controlling our thoughts
2.Nihilistic delusion that things don’t exist
3. Delusions of grandeur patient believes he or she has special powers, talents, or abilities. E.g. believe they are an important historical, political or religious figure, such as Jesus.
4. Persecutory delusions when a person believes he or she is being tormented, followed, tricked, spied on, or ridiculed E.g. government or aliens after them.
What is speech poverty (negative symptom)
Reduction in the amount and quality of speech.
Sometimes accompanied by a delay in verbal responses during a conversation.
Nowadays more emphasis is placed on speech disorganisation in which speech becomes
incoherent or the speaker changes topic mid -sentence.
What is avolition? (negative symptom)
Sometimes called apathy, means finding it difficult to begin or keep up with goal-directed activity.
People with schizophrenia often have sharply reduced motivation to carry out a range of activities
What does validity mean in diagnosis?
Validity is concerned with whether or not there is a real difference between illnesses. If so such illnesses should exhibit symptoms/ features that distinguish themselves from one another.
What does reliability mean in diagnosis?
Reliability is concerned with the fact that if we do find a real difference between illnesses (and so the diagnosis is valid) then we should be able to consistently distinguish between the illnesses based upon such differences.
Strength of diagnosis of schizophrenia - GOOD RELIABILITY IN DIAGNOSIS
P: One strength of the diagnosis of schizophrenia is its reliability due to its consistency.
EE: A psychiatric diagnosis is reliable when different clinicians conclude the same
diagnosis for the same individual (inter-rater reliability) and when the same clinician reaches the same diagnosis for the same individual on two occasions (test- retest reliability).
Prior to DSM-5, reliability for schizophrenia diagnosis was low but this has now
improved. Osório et al (2019) report excellent reliability for the diagnosis of
schizophrenia in 180 individuals using the DSM-5. Pairs of interviewers achieved inter-rater reliability of +97 and test-retest reliability of +.92.
L: This means that we can be reasonably sure that the diagnosis of schizophrenia is
consistently applied.
Limitation of diagnosis of schizophrenia - ISSUES WITH VALIDITY IN DIAGNOSIS
P: One limitation of the diagnosis of schizophrenia is that there is low validity.
EE: Validity concerns whether we assess what we are trying to assess.
Criterion validity is used to assess the validity of psychiatric diagnosis. Cheniaux et al. (2009) had two psychiatrists independently assess the same 100 clients using ICD-10 and DSM-IV criteria and found that 68 were diagnosed with Schizophrenia under
the ICD system and 39 under DSM. This suggests that schizophrenia is either over- or under-diagnosed according to the diagnostic system.
L: This suggests that criterion validity is low based on the diagnostic system
Counterpoint- CAN OVERCOME DIAGNOSTIC ISSUES
Counterpoint:
Osório et al. study reported there was excellent agreement between clinicians when they used two measures to diagnose schizophrenia both derived from the same DSM system
This means that the criterion validity for diagnosing schizophrenia is high,
only if it uses a single diagnostic system.
Limitation of diagnosis of schizophrenia - CO-MORBIDITY AND CLASSIFICATION
P: Another limitation of schizophrenia diagnosis is its co-morbidity and similarity with other conditions may decrease the validity of classification.
EE: If conditions occur together too often, then this questions the validity of their diagnosis and classification because they might actually be a single condition.
One review found that about 1/2 of those diagnosed with schizophrenia also had a
diagnosis of depression or substance abuse (Buckley et al.). This is a problem for classification because it means schizophrenia may not exist as a distinct condition, and is a problem for diagnosis as at least some people diagnosed
with schizophrenia may have unusual cases of conditions like depression.
L: This therefore decreases the validity of classification of schizophrenia, which in turn
also affects that diagnosis.
Limitation of diagnosis of schizophrenia - GENDER BIAS IN DIAGNOSIS
P: A further limitation of schizophrenia diagnosis is that it may be influenced by
gender bias.
EE: Since the 1980’s men have been diagnosed with schizophrenia more commonly
than women (a ratio of 1.4:1, Fischer and Buchanan 2017). One possible explanation for this is because of genetic factors. However it seems more likely that women are underdiagnosed because they have closer relationships and hence get support (Cotton et al. 2009). This leads to women with schizophrenia often functioning better than men
L: This underdiagnosis is a gender bias and means women may not therefore be receiving treatment and services that might benefit them
Limitation of diagnosis of schizophrenia - CULTURE BIAS IN DIAGNOSIS
P: A further limitation of schizophrenia diagnosis is that it may be influenced by
culture bias.
EE: Some symptoms of schizophrenia, particularly hearing voices, have different meanings in different cultures. For example in Haiti some people believe that
voices actually are communications from ancestors. British people of African-Caribbean origin are up to nine times as likely to
receive a diagnosis as white British people (Pinto and Jones 2008). Whilst this
may suggest genetic vulnerability, the most likely explanation for this is culture
bias in diagnosis of clients by psychiatrists from a different cultural background. It seems there is an overinterpretation of symptoms in black British people (Escobar 2012).
L: This suggests that British African-Caribbean people may be discriminated against by a culturally-biased diagnostic system
Limitation of diagnosis of schizophrenia - SYMPTOM OVERLAP
P: On other limitation of schizophrenia diagnosis is that there is overlap with other conditions.
EE: For example, both schizophrenia and bipolar disorder involve positive symptoms (e.g. delusions) and negative symptoms (avolition). In terms of classification this suggests that schizophrenia and bipolar disorder may not be two different conditions but variations of a single condition. In terms of diagnosis it means that schizophrenia is hard to distinguish from bipolar disorder.
L: Similar to co-morbidity, symptom overlap means that schizophrenia
may not exist as a distinct condition. Or, that even if it does, it is hard to diagnose. Therefore, both its classification and diagnosis
are flawed.
