Issues in the diagnosis of schizophrenia Flashcards
What are the issues in the diagnosis of schizophrenia?
- Reliability and validity
- Comorbidity
- Overlapping symptoms
- Gender and cultural bias
What are the types of reliability?
- Inter-rater reliability
- Test-restest reliability
What is inter-rater reliability?
Occurs when clinicians make identical, independent diagnosis of the same patient
What are the pieces of research for inter-rater reliability?
- Beck et al found that when a group of 153 patients with schizophrenia were each assessed by 2 different psychiatrists, the diagnosis agreement rate was only 54%
- Copeland gave a description of a patient to 134 US and 194 British psychiatrists and found that 69% of the US psychiatrists diagnosed the patient with schizophrenia, whereas only 21% of British psychiatrists gave the same diagnosis.
What is test-retest reliability?
Occurs when clinicians make the same schizophrenia diagnosis of the patient on separate occasions from the same information.
Although clinicians have detailed manuals to use we must accept that patients with schizophrenia, and their symptoms change with time.
If the point is:
A weakness of the reliability of diagnosis is that there is research which reveals the problems with inter-rater reliability of the diagnosis of schizophrenia.
What is the evidence and link?
Evidence- For example, the Copeland study. Copeland gave a description of a patient to 134 US and 194 British psychiatrists and found that 69% of the US psychiatrists diagnosed the patient with schizophrenia whereas only 21% of British psychiatrists gave the same diagnosis.
Link- This shows that American clinicians are far more likely to diagnose schizophrenia than their UK counterparts.
If the point is:
A weakness of the reliability of diagnosis is that Read reported that test-retest analysis is as low as 37% for schizophrenia which is extremely concerning, especially when we consider the potential false positives and false negatives this could create.
What is the evidence and link?
Evidence- For example, not making a diagnosis when a person has schizophrenia, leading to them receiving no treatment.
Link- This could imply that this type of reliability is not actually that reliable and should be very careful when it is being used.
If the point is:
A strength of the reliability of diagnosis is that a way to improve it has been highlighted by Farmer.
What is the evidence and link?
Evidence- Farmer found that a standardised interview technique, known as the present state examination, increases the reliability of diagnosing schizophrenia. This is because it focuses on the frequency and severity of symptoms, meaning all patients are asked these things.
Link- This suggests that reliability of diagnosis may have some credibility.
If the point is:
A strength of the reliability of diagnosis is that the DSM has improved it through revising the criteria.
What is the evidence and link?
Evidence- The DSM has now stripped the criteria from the diagnostic guide, as it was difficult to differentiate between bizarre delusion and non bizarre delusions. For example, within religion.
Link- This supports the notion that the DSM has helped to increase the reliability of diagnosis by adapting and changing certain specific criteria to make diagnosis more consistent.
What are the evaluation points for the reliability of diagnosis?
— A study to highlight the problems with inter-rater reliability of the diagnosis of schizophrenia was conducted by Copeland and illustrates how the culture of the clinician can damage inter-rater reliability.
— Read reported that test-retest analysis is as low as 37% for schizophrenia, which is extremely concerning, especially when we consider the potential false positives and false negatives this could create.
+ A way to improve reliability for diagnosing schizophrenia has been highlighted by Farmer.
+ The DSM has improved the reliability of diagnosis through revising the criteria.
What can the validity of diagnosis be affected by?
- Comorbidity
- Overlapping symptoms
What is comorbidity?
- When more than 1 disorder or disease exists alongside a primary diagnosis
- Where 2 conditions are frequently diagnosed together it calls into question the validity of the classification of both illnesses and perhaps the combination of schizophrenia and personality disorder.
(Validity)
What are overlapping symptoms?
- None of the symptoms of schizophrenia are exclusive to the disorder, making a valid diagnosis difficult to achieve.
- Bipolar disorder, OCD and autism are amongst many disorders that have overlapping, typical symptoms with schizophrenia.
- It’s estimated that about 13% of the population hear voices but only 1% are diagnosed with schizophrenia.
(Validity)
If the point is:
A weakness of validity of diagnosis is that comorbidity reduces the validity of diagnosis, as a clinician could make an inaccurate diagnosis due to the additional disorder.
What is the evidence and link?
Evidence- Buckley et al identified the following comorbid conditions with schizophrenia and argues they could be subtypes of schizophrenia. The following were reported with schizophrenia: 29% PTSD, 50% depression and 47% substance abuse. The prevalence of depression with schizophrenia is widely acknowledged yet poorly understood.
Link- This suggests that close attention should be paid to each behaviour of the individual.
If the point is:
A weakness of validity of diagnosis is that we must really reconsider comorbid conditions and schizophrenia, as patients can actually suffer from 2 or more mental health states.
What is the evidence, explanation and link?
Evidence- For example, is it that they have 2 separate conditions, or that they actually have a completely different condition that combines their symptoms. For example, depression and schizophrenia are often comorbid (50%) with patients experiencing low mood alongside psychotic symptoms. However, are these patients just being misdiagnosed and actually have a different condition, such as type 1 bipolar, a mental health condition that incorporates depressive, manic and psychotic episodes.
Explanation- Surely that is a unique condition as opposed to 2 states that coexist and receive 2 separate diagnoses. This has been partly addressed in DSM V, but problems remain with comorbidity and schizophrenia.
Link- Therefore, the validity of diagnosis fir schizophrenia may actually be quite low.