issues of validity in the classificationa nd diagnosis of schizophrenia

What does it mean by validity of diagnosis of schizophrenia

When a patient is diagnosed with schizophrenia

Is that diagnosis trustworthy in terms of describing the illness that they have and the outcomes (prognosis) of that illness

What is criterion validity

Do different assesments systems arrive at the same diagnosis for the same patient

What is cheniaux study to do with criterion validity

CHENIAUX study

Where 2 psychiatrists independently assessed the same 100 patients using both DSM and ICD

For psychatrists one they found 26 people with it using DSM compared to the 2nd psych. Finding 13

ICD - Psych.1 was 44 and Psych.2 was 24

What does cheniaux study suggests about schizophrenia to do with criterion validity?

Schizophrenia is much more likely to be diagnosed using iCD

Suggests schizophrenia is either over diagnosed in ICD or under diagnosed in DSM

Either way this is poor validity - weakness

What has ICD is improved in

ICD - on version 11 - it has improved in criterion validity

Brought closer to the DSM

What is predictive validity

Can a diagnosis of schizophrenia be used to predict what the long term outcome fo the patient will be and what treatment will be most effective

What is the outcome of an illness called?

Prognosis

What did Mason find to do with predictive validity

MASON found that over time the diagnostic tools used to diagnose 99 schizophrenic patients had improved in the accuracy of diagnosis and identifying the most effective treatment

Suggests the predictive validity had improved

What’s a weakness o predictive validity? Who described this?

Bentall

Found doctors were unable to fully predict the prognosis of patients

A diagnosis of schizophrenia wa highl variable

20% of patients fully recover

10% make a very god but not full, recovery

30% make some improvement and occasionally have relapses

40% of patients make little or no improvement

What dos Bntalls study suggest

Suggests there’s a problem in predicting what the outcome for a patient will be

Which questions the validity of a diagnosis of schizophrenia.

However this is an older study

Might be the criteria tested by MASON et al were an improvement on that used by BENTALL ET AL

What is descriptie validity ?

Symptom overlap with other illnesses -

If schizophrenia is a valid illness it shouldn’t have a large overlap with any other illness

If here is a large overlap with another illness this would suggest that schizophrenia may be another illness

What study supports schizophrenia has descriptive validity

How many patients ?

What were the different disorders (4)

JÄGER

• used ICD 10to diagnose the illness of 1500 patients not all whom had schizophrenia

• If schizophrenia is a valid illness - should be possible to identify who has schizophrenia and who has a different illness

• Found using the ICD 10 the doctors were correctly able to identify the 4 different disorders

• Schizophrenia + delusional disorders + acute transient psychosis + schizoaffectve disorders

• Suggests that schizophrenia does have descriptive validity

What’s a weakness i the overlap? Study?

A sweaness in overlap is shown by ELLASON AND ROSS

Who point out that people with dissociative identity disorder often have more of the symptoms of schizophrenia than schizophrenics have

When is overlap most likely to happen? What are the symptoms? What does th broad overlap make it difffcult for?

Symptom overlap between schizophrenia and other disorder is more likely in the early stages of diagnosis

The symptoms are often non- specific, frequently resembling those at anxiety disorders, depressive episodes or even stress reaction.

E.g social withdrawal, irritability, difficulty concentrating

The broad overlap makes it difficulty for clinicians to identify individuals who are truly at risk for or in the very early stages of schizophrenia

What is missed as a reuslt of clinicians not being able to identify idnivuals who are at risk for for schizophrenia

Valuable opportunities for early intervention which is known to significantly improved long term prognosis and reduce the severity of the illness are often missed