Schizophrenia - Classification and Diagnosis Flashcards
Implications of classification and diagnosis?
Misdiagnosis, Stigma, Advantages
Misdiagnosis could lead to…
incorrect or no treatment, which will affect progress (recovery) and general outcomes
Stigma could…
affect career (e.g. health questionnaires when applying, promotions), personal and social life
Advantages of classification and diagnosis?
Determines treatment, information on implications/course of SZ, gives professionals a shared language
Kendell and Jablensky?
Diagnostic categories are justifiable concepts and a useful framework for organising and explaining
Reliability?
Refers to the consistency of a measuring instrument, such as the DSM
How can reliability be measured?
Through inter-rater reliability or test-retest reliability
Issues of reliability?
Low inter-rater reliability, unreliable symptoms, differences between the DSM and ICD
Relationships between reliability and validity?
If it’s not reliable it can’t be valid - if psychologists can’t agree who has SZ (reliability) then what is it? (validity)
Low inter-rater reliability?
There have been improvements but it remains an issue
Researchers on low inter-rater reliability?
Beck BUT Carson BUT Whaley
Beck?
Early versions of manuals weren’t very reliable as key terms weren’t clearly deigned and clinicians used different interview techniques
Carson?
DSM-III has overcome problems described by Beck and has inter-rater reliability
Whaley?
Found inter-rater reliability correlations as low as +0.11
Implications of low inter-rater reliability?
Misdiagnosis and therefore stigma
Issue with unreliable symptoms?
Some symptoms aren’t consistently identified by clinicians - they must be able to decide whether a symptom is present or not to make a diagnosis, but SZ is difficult to diagnose as there are no physical signs or definitive tests
Researchers on unreliable symptoms?
Mojtabi and Nicholson
Mojtabi and Nicholson?
Asked 50 senior psychiatrists in the US to differentiate between bizarre and non-bizarre symptoms and found IRR of +0.4
DSMs and unreliable symptoms?
DSM-IV only requires 1 symptom if delusions are bizarre (the key symptom) BUT DSM V required 2 symptoms so no longer a problem
Implications of unreliable symptoms?
While it’s no longer an issue it may’ve led to misdiagnosis in the past so may still be affecting individuals
Issue with differences between the DSM and ICD?
Individuals should receive the same diagnosis from each if reliable
What are the differences between the DSM and ICD?
More likely to be diagnosed with the ICD (requires 1 month of symptoms) than the DSM (1 month of symptoms + 6 months of disturbance/social occupational dysfunction)
Researcher on differences between the DSM and ICD?
Copeland
Copeland?
69% of 134 US psychologists (DSM) and 2% of 184 British ones (ICD) diagnosed SZ
Implications of differences between the DSM and ICD?
Misdiagnosis or no diagnosis at all
How are differences between the DSM and ICD being fixed?
Organisations such as WHO and APA have recognised the issue and have worked to produce the DSM V to improve reliability
Issues of validity in classification and diagnosis?
Predictive validity, comorbidity
What is validity?
The extent that a diagnosis represents something that’s real and distinct from other disorders, and the DSM and ICD measure what they claim to
Issues with predictive validity?
If SZ is a valid disorder then patients should share the same outcomes and on that basis clinicians should be able to predict outcomes, but there are a lot of individual differences in response to treatment and outcomes
Research on predictive validity?
Bentall et al
Bentall et al?
20% of SZs responded to treatment and recovered previous levels of functioning, 10% achieved significant and lasting improvements, 30% some improvement with intermittent relapses
What does Bentall’s research show?
SZ may not be a single unitary disorder so classification as a distinct disorder may not be valid
Implications of predictive validity?
Brings into question one of the main aims of classification and diagnosis: deciding treatment - how clinically useful is C&D really?
What is comorbidity?
The extent to which 2 conditions co-occur, e.g. SZ and substance abuse, anxiety etc.
Research on comorbidity?
Buckley et al and Kessler et al
Buckley et al?
Estimated comorbid depression in 50% of SZs and that 47% have a lifetime diagnosis of substance abuse
Kessler et al?
National Comorbidity Survey - attempted suicide rate 1% for those with SZ alone, 40% of those with at least 1 lifetime comorbid disorder
Issue with comorbidity?
It’s difficult to determine cause - is it SZ or a 2nd condition? If classification is valid the causes should be clear and the same for everyone
Implications of comorbidity?
Which disorder should be focussed on? Therefore what treatment?
