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Schizophrenia - Reliability + validity in diagnosis and classification -…
Schizophrenia - Reliability + validity in diagnosis and classification
Reliability
Diagnosis must be
repeatable
Test-retest reliability:
same conclusion at different points in time
Inter-rater reliability:
different clinicians must reach the same conclusion (Kappa score)
Reliability - Inter-rater: Cheniaux
2 Psychaitrists assessed 100 patients using DSM (what Americans use) + ICD (what Europe countries use)
Found Inter-rater reliability was poor
E.g. 1 psychaitrist: diagnosed 26 using DSM + 44 using ICD to diagnose sz
This shows that schizophrenia is over or under diagnosed using different systems
Reliability - Inter-rater - Regier
Kappa score: usually any score of greater than 0.7 is generally considered good
But the DSM-5 Kappa score was only of 0.46
Shows us that inter-rater reliability is a key weakness of the diagnosis of schizophrenia
the low kappa score to state that this is an effective diagnosis tool
Co-morbidity
Extent that
2 (or more) conditions co-occur
If conditions occur together a lot of time it calls into question the validity of their diagnosis because they might actually be a single condition
Co-morbidities are common with schizophrenics (OCD, depression)
So it might be the fact that these are actually one condition rather than being separate conditions - makes treatment difficult
Co-Morbidity - Buckley
Co-morbid depression occurs in 50% patients
There are 2 possible conclusions we can draw from this: maybe we are bad at telling the difference between the 2 conditions
Or if they are similar maybe they might be between seen as a single condition
Co-morbidity paints a very confusing picture when we diagnose sz
Gender Bias
Diagnosis is dependent on the gender of the patient
Gender biased criteria OR clinicians base judgements on stereotypical beleifs
Men = more likely to develop sz, so are more likely to diagnose a male with it
Powell
- study on 290 male + female psychiatrists
Each psychiatrist was given 2 case studies of patient behaviours
When patient was described as 'male' - 56% were diagnosed with sz
When described as 'female' - 20% diagnosed with sz
However, this evidence of gender bias was not present with female psychiatrists
Condclude - gender of patients + psychiatrists is clearly a factor in the diagnosis of sz
Gender Bias - Longnecker
Since 1980 - men are more often diagnosed than men
He said that this is because men are more genetically vulnerable
OR that there is gender bias - women function better than males with the disorder - e.g. more likely to work, better relationships - this may bias practitioners to under-diagnose sz because they don't come across as showing the characteristics that are associated with sz
Cultural bias
African American/Caribbean origin
- several times more likely than white people to be diagnosed
Rates in Africa + West Indies
- not high rates = can't be genetic vulnerability
Positive symptoms
= more acceptable in
African cultures
When reported in different culture = seen as bizarre + irrational + diagnose someone with sz
Escobar:
white psychiatrists distrust the honesty of black people during diagnosis
Cultural bias - Copeland
Countries/cultures have differences in diagnosis
200 US + UK psychiatrists + gave them a description of a patient
69% of US psychiatrists diagnosed the patient with sz
ONLY 2% were diagnosed in the UK
Lack of Objective Tests
There is no biological test for the determining whether a person has sz
Assessment must be sone through a clinical interview
Led to major problems + has led to some critics to argue that if sz cannot be diagnosed physically then it may not be a disorder at all