Diagnosis, reliability, validity, class systems

Question 1

What determines whether a patient is diagnosed with schizophrenia?

Answer 1

Two or more negative symptoms must be present for at least a month.

Question 2

What is a classification system?

Answer 2

A group of symptoms of a syndrome with an underlying cause, separate from other disorders.

A diagnostic and statistical manual of mental disorder

Question 3

Describe the DSM-IV

Answer 3

Developed by American Psychiatric Association.
Used mainly in the US.
Diagnose schizophrenia with an inter-rater reliability of 0.8.
Specifies the presence of one first rank symptom, or two symptoms from a list of positive or negative symptoms.
Minimum duration of symptoms for 6 months, incl. prodromal symptoms and includes deterioration of social functioning.
Dsm-iv schizophrenia has a lower incidence and prevalence rate than icd-10 schizophrenia… therefore a worse prognosis due to the degree of chronicity.

Question 4

Describe the ICD-10

Answer 4

Developed by World Health Organisation
Used .
Diagnose schizophrenia with an inter-rater reliability of 0.8.
Specifies the presence of one first rank symptom, or two symptoms from a list of positive or negative symptoms.
Minimum duration of symptoms for 1 month.

Question 5

Explain Reliability

Answer 5

Consistency of symptom measurement and affects diagnosis
There are two ways to measure reliability: Test-retest and Inter-rater

Question 6

What is test-retest?

Answer 6

Occurs when a clinician makes the same diagnosis on separate occasions using separate information.

Question 7

What is inter-rater?

Answer 7

Different clinicians make identical, independent diagnosis.

Question 8

How is inter-rater reliability measured?

Answer 8

by a statistic known as kappa score
1-0
1= perfect inter-rater agreement
0= zero agreement
0.7= considered as good

DSM-V trials for diagnosis of schiz has a score of 0.46. (Reiger et al)

Question 9

Describe Beck et al

Answer 9

1962
54% CR using inter-rater reliability
among psychiatrists
Assessed 153 patients

Question 10

Describe Soderberg

Answer 10

2005
81% CR using DSM
shows classification systems to have become more reliable over time

Question 11

Describe Baca- Garcia

Answer 11

Test-retest
2322 patients in spanish psychiatric hospital between 1922- 2004
assessed 10x = 2/3 kept diagnosis

Question 12

Describe Jacobsen et al

Answer 12

2005
test-retest
found a concordance rate of 98% among psychiatrists using the ICD-10 classification to diagnose schizophrenia.
Supports sodeberg.

Question 13

Explain validity into schizophrenia

Answer 13

Concerns how accurate a diagnosis is.
Schiz should be separate from other disorders (e.g. substance abuse etc)
There are three ways to measure:
predictive v
descriptive v
aetiological v

Question 14

Describe predictive validity

Answer 14

If diagnosis leads to successful treatment, then the diagnosis is seen as valid

Question 15

Describe descriptive validity

Answer 15

To be valid, patients should differ in symptoms from patients with other disorder (no overlap)

Question 16

Describe Aetiological validity

Answer 16

To be valid, all schizophrenics should have the same cause for the disorder

Question 17

Describe Mason et al

Answer 17

The test ability of four different class systems predict the outcome of the disorder (over 13 years) in 99 schizophrenics.
More modern class systems have higher predictive v especially if only symptoms lasting 6 mo considered.

TS= Predictive diagnosis has improved over time, as classification systems improved and updated.

Question 18

Describe Rosenhan

Answer 18

1973
Aim= test the v of schiz diagnosis using the DSM-II class system

Method= 8 volunteers (no mental health illness)
Presented themselves to different mental hospitals, claiming to hear voices.
all admitted, then started acting normal.
Time taken to be released and reactions are recorded.

Findings= volunteers took 7-52 days to be released, diagnosed as schizophrenics in remission.
normal behaviours= interpreted as signs of schiz.
35/118 actual patients suspected they had schiz.
3 month period= 193 patients admitted.
83 aroused suspicion of them being false patients

Question 19

Describe Jager et al

Answer 19

Descriptive V

Question 20

Describe Baillie et al

Answer 20

2009
154 British psychiatrists found that other than an agreement as to the influence of genetics, biochem abnormalities and substance abuse; there are widely different views on the cause of schiz.

Aetiological v of schiz is low.

Question 21

AO3 - Perfection?- R

Answer 21

Class systems are not perfect
HE they provide practicioners with common language, permitting the communication of research ideas and findings… lead to better understanding

Leads to effective symptoms

Link to eva for antipsychotics

Versions modified over time : DSM-5 and ICD- 10

Question 22

AO3- Improvement over time- R

Answer 22

more reliable over time (class symptoms)
supported by Jakobsen and soderbeg
TS= benefitting society

Question 23

AO3- Invalid diagnosis- V

Answer 23

no mention of the cause in class symptoms
no mention of prevalence rates which differ from rural to urban areas
supported by Baillie et al

Question 24

AO3- Consequences- V

Answer 24

consequences if there is invalid diagnosis

being labelled as a schizophrenic has long lasting negative effect onto the individual

affect social relationship