Reliability and validity in the diagnosis and classification of schizophrenia Flashcards
what does reliability refer to
consistency
if a diagnosis is reliable what does this mean
it is consistent over time and by different psychiatrists
what is inter-rater reliability
when two independent psychiatrists agree on a diagnosis of schizophrenia
what is test-retest reliability
when the same person gives the same diagnosis using the same criteria on two separate occasions
what is validity
the extent to which we are measuring what we intended to measure
how can you assess the validity of a diagnosis of schizophrenia
criterion validity
what is criterion validity
using two different measures and seeing if they arrive at the same diagnosis of schizophrenia
what are the two diagnostic systems
ICD and DSM
what does ICD stand for
international classification of diseases and related health problems
what does DSM stand for
Diagnostic and statistical manual of mental disorders
to be diagnosed with schizophrenia what does the DSM say you have to have to be diagnosed with schizophrenia
two or more symptoms for at least one month
to be diagnosed with schizophrenia what does the ICD say you have to have to be diagnosed with schizophrenia
one very clear symptom
what is a key difference between the DSM and the ICD
two negative symptoms are sufficient under the ICD
why does the reliability and validity of diagnosing schizophrenia matter
misdiagnosis-people might be diagnosed with schizophrenia when they don’t have it
people that do have schizophrenia might be misdiagnosed as not having schizophrenia when they do
this is bad because antipsychotic drugs have strong side effects. That could negatively effect mental health in people who are inappropriately given these drugs
what are the two research evidence points for whether schizophrenia diagnosis and classification is NOT reliable or valid
Rosenhan-pseudopatients
Cheniaux et al-two psychiatrist
explain Rosenhan’s study
pseudopatients where presented to 12 different psychiatric institutionswith a single symptom of hearing a voice saying ‘hollow, empty, thud’ once admitted they behaved normally. all but one of the patients were given the label of paranoid schizophrenia with the other patient being labelled at bipolar
they then did a follow up study and said to institutes he would send them more pseudopatients. after three months they were confident about a third of new patients sent were pseudopatients when none had actually been sent
how does Rosenhan not support the reliability or validity of the diagnosis and classification of schizophrenia
Reliability: the diagnosis was not consistent one was diagnosed with bipolar despite displaying identical symptoms
Validity: psychiatrists were not able to tell the difference between real and fake patients - they misdiagnosed healthy people as having schizophrenia and diagnosed mentally ill patients as healthy
explain Cheniaux et al’s study
two psychiatrists independently diagnosed 100 patients using the DSM and ICD. one psychiatrist diagnosed 26 with schizophrenia using the DSM and 44 according to the ICD the other diagnosed 13 as having schizophrenia using the DSM and 24 with the ICD. The psychiatrists interpreted the criteria differently
how does Cheniaux et al not support the reliability or validity of the diagnosis and classification of schizophrenia
reliability: poor inter-rater reliability
validity: suggests the correct diagnosis is not always given. Either DSM is underdiagnosing or ICD is over diagnosing
what causes problems with diagnosis
comorbidity
symptom overlap
gender bias
cultural bias
explain comorbidity
schizophrenia is commonly diagnosed alongside other conditions
50% of schizophrenic patients also have depression
47% have substance abuse
29% have PSTD
23% have OCD
why does comorbidity make the diagnosis of schizophrenia less valid and reliable
reliability: different psychiatrists may not agree on what the primary diagnosis should be
Validity: schizophrenia may be missed and diagnosed as a more common disorder
why does comorbidity have challenges on treatment
treatments for different disorders may counteract each other. need to decide what disorders to prioritise for treatment
what is symptom overlap
overlap between symptoms of other conditions and schizophrenia
schizophrenia and bipolar both have symptoms of avolition and delusions
why does symptom overlap make the diagnosis and classification less valid and reliable
Reliability: psychiatrists may not agree
Validity: incorrect diagnosis might be given
what is gender bias in diagnosis of schizophrenia
men are more likely to receive diagnosis of schizophrenia than women this is because men are more genetically vulnerable than women
Women with schizophrenia tend to function better more likely to work and maintain good family relationships and tis could lead to women being underdiagnosed
why does gender bias consequences matter
women who are misdiagnosed will receive the wrong treatment
the more women underdiagnosed the greater the gender difference in schizophrenia will be, leading to more women being misdiagnosed
what did Cotton find relating to gender bias
women with schizophrenia tended to report more mood symptoms than men, this means they are more likely to be diagnosed with depression or bipolar disorder
what is cultural bias in the diagnosis of schizophrenia
people of Afro-Caribbean origin are significantly more likely to be diagnosed with schizophrenia it is not due to a genetic vulnerability because the rates of schizophrenia in Africa and Caribbean are not any higher in Europe
therefore it must be cultural bias
hearing voices is acceptable in African cultures because of cultural beliefs and communication with ancestors
what did Kim and Berrios find relating to cultural bias
in Japan the thought of disorganised mind is so stigmatising that psychiatrists are reluctant to diagnose patients with schizophrenia. As a result only 20% of Japanese people with schizophrenia are aware of it
