Reliability and validity in diagnosis and classification

Question 1

What is diagnostic reliability?

Answer 1

diagnosis of schizophrenia must be repeatable - clinicians must be able to reach the same conclusions at two different points in time (test-retest reliability) or inter-rater reliability (different observers reach same conclusion) - use kappa score - typically 0.7 or above is good

Question 2

What did Copeland find about cultural differences in diagnosing schizophrenia?

Answer 2

Gave 134 US and 194 UK psychiatrists a description of patient
69% of US diagnoses schizophrenia as opposed to 2% of UK

Question 3

What did Luhrmann et al find about cultural differences in diagnosing schizophrenia?

Answer 3

Interviewed 60 adults with schizophrenia
20 each in Ghana, India and US
African and Indian subjects reported positive experiences with ‘voices’ describing them as playful and offering advice while US subjects described them as violent and hateful and indicative of being sick

Question 4

What is gender bias in diagnosis?

Answer 4

Accuracy of diagnosis is dependent of gender if the individual

Question 5

What did Broverman et al find?

Answer 5

Clinicians in the US equated mentally healthy adult behaviour with mentally healthy male behaviour = tendency for women to be perceived as less mentally healthy

Question 6

What is symptom overlap?

Answer 6

Symptoms of one disorder may not be unique to that disorder but also may be found in others, making accuracy of diagnosis difficult

Question 7

What is co-morbidity?

Answer 7

Refers to the extent that two (or more) conditions occur simultaneously in a patient e.g. schizophrenia and depression

Question 8

What did Buckley et al estimate?

Answer 8

Co-morbid depression occurs in 50% of schizophrenic patients

Question 9

Why is the DSM an unreliable?

Answer 9

Difficult to reliably distinguish between schizophrenic and non-schizophrenic patients
Mojabi and Nicholson - when 50 senior psychiatrists were asked to differentiate between bizarre and non-bizarre delusions, the inter-rater reliability correlations were only around 40%

Question 10

What evidence is there for gender bias in diagnosis?

Answer 10

Loring and Powell - randomly selected 290 male and female psychiatrists to read 2 cases, asked to offer their judgment using standard diagnostic criteria
when patient described as males/no gender info - 56% diagnosed with schizophrenia compared to only 20% if described as female (female psychiatrists did not have this gender bias)