Issues Surrounding Classification & Diagnosis

Question 1

What are the 2 issues regarding the classification and diagnosis of SZ?

Answer 1

Reliability and validity

Question 2

What is meant by reliability for SZ?

Answer 2

Refers to the consistency of a measuring instrument like a questionnaire to assess the severity of their SZ symptoms

Question 3

What are the 2 measurements of reliability for SZ?

Answer 3

Inter-rater reliability and test-retest reliability

Question 4

What is meant by inter-rater reliability for SZ?

Answer 4

Whether 2 independent assessors give similar diagnoses

Question 5

What is meant by test-retest reliability for SZ?

Answer 5

Whether tests used to deliver diagnoses are consistent over time

Question 6

Outline inter-rater reliability for SZ

Answer 6

The publication of DSM in 1980 specifically designed to provide a much more reliable system for classifying psychiatric disorders

Question 7

What is the study associated with inter-rater reliability for SZ?

Answer 7

Carson (91)

Question 8

Outline Carson (91)

Answer 8

Reviewed success of the DSM and claimed it had fixed problem of IRR once and for all - psychiatrists now had a reliable classification system so this should have led to much greater agreement over who did or did not have SZ

Question 9

Outline test-retest reliability for SZ

Answer 9

Cognitive screening tests like RBANS are important in diagnosis of SZ as they will measure the extent of neurological impairment

Question 10

What study is associated with test-retest reliability for SZ?

Answer 10

Wilks (03)

Question 11

Outline Wilks (03)

Answer 11

Administered 2 alternate forms of tests to SZ patients over interval varying 1-134 days and found TRR correlation of scores across 2 test periods was high at 0.84

Question 12

Name 5 negative points for the reliability of SZ

Answer 12

1) IRR Whaley (01)
2) Rosenhan (73)
3) Unreliable symptoms - Mojtabi & Nicholson (95)
4) DSM vs ICD - Cheniaux (09)
5) Cultural differences

Question 13

Outline IRR and Whaley (01) for SZ

Answer 13

Despite claims of increased reliability, over 30 years later and there is still little evidence that DSM is routinely used with high reliability by mental health clinicians - Whaley (01) found IRR correlations as low as +0.1

Question 14

Outline Rosenhan (73)

Answer 14

Highlighted the unreliability of diagnoses of SZ - ‘normal’ people presented to psychiatric hospitals in US claiming heard unfamiliar voices in heads saying words like ‘empty’ ‘hollow’ and ‘thud’ - all diagnosed with SZ and admitted - throughout their stay, none of the staff recognised they were actually normal - in a follow-up study, Rosenhan warned hospitals of intention to send out more ‘pseudo patients’ resulted in a 21% detection rate although non actually presented themselves

Question 15

Outline unreliable symptoms for the reliability of SZ

Answer 15

For diagnosis, only one of the characteristic symptoms required if ‘delusions are bizarre’ - Mojtabi & Nicholson (95) got 50 senior psychiatrists in US and asked them to differentiate between bizarre and non-bizarre delusion and produced IRR correlations of only +0.4 hence concluded even this central diagnostic requirement lacks sufficient reliability for it to be a reliable method of distinguishing between SZ and non-SZ patients

Question 16

Outline DSM vs ICD - Cheniaux (09)

Answer 16

Investigated IRR of diagnoses according t both DSM and ICD and although IRR was above +0.5 for both classificatory systems, SZ more frequently diagnosed according to ICD than DSM criteria

Question 17

Outline the cultural differences in the classification and diagnosis of SZ

Answer 17

Copeland (73) gave 134 US & 194 British psychiatrists a description of a patient - 69% of US diagnosed SZ but only 2% of British gave same diagnosis thus showing there is massive variation between countries in the diagnosis of SZ

Question 18

Name and explain a positive point about the reliability of classifying and diagnosing SZ

Answer 18

TTR - measures of cognitive functioning are vital in diagnoses and so must have TTR to be useful - Prescott (86) analysed TRR of several measures of attention and information processing in 14 chronic SZs and found performance of these measures was stable over a 6 month period

Question 19

What is meant by validity in terms of SZ?

Answer 19

Refers to the extent that a diagnosis represents something that is real and distinct from other disorder and extent that a classification system like the ICD and DSM measures what it claims to measure

Question 20

What is important to note about reliability and validity in terms of SZ?

Answer 20

They are inextricably linked as diagnoses cannot be valid if it is not reliable

Question 21

Name the 3 aspects of validity in terms of the classification and diagnosis of SZ

Answer 21

1) Comorbidity
2) Positive or negative symptoms?
3) Prognosis

Question 22

What is comorbidity?

Answer 22

The extent that 2 or more conditions co-occur

Question 23

Outline comorbidity in terms of SZ

Answer 23

Psychiatric comorbidities are common among patients with SZ including substance abuse, anxiety and symptoms of depression - such comorbidity creates difficulties in diagnosis and deciding what treatment

Question 24

Name the main study associated with comorbidity for SZ

Answer 24

Buckley (09)

Question 25

Outline Buckley (09)

Answer 25

Estimate that comorbid depression occurs in 50% of patients and 47% of patients also have lifetime diagnosis of comorbid substance abuse

Question 26

What is the study associated with positive or negative symptoms for the classification and diagnosis of SZ?

Answer 26

Klosterkotter (94)

Question 27

Outline Klosterkotter (94)

Answer 27

Assessed 489 admissions to psychiatric unit in Germany to determine whether positive or negative symptoms were more valid in diagnosis of SZ - found positive symptoms were more useful for diagnosis than negative (these symptoms differentiated the illness from any other disorders)

Question 28

Outline prognosis for the classification and diagnosis of SZ

Answer 28

People diagnosed as SZ rarely share the same symptoms nor is there any evidence they share the same outcomes therefore diagnosis of SZ has little predictive validity - some never appear to recover but many do

Question 29

What is the main study associated with the prognosis for the classification and diagnosis of SZ?

Answer 29

Bentall (88)

Question 30

Outline Bentall (86)

Answer 30

Prognosis for patients varies - 20% recovering from previous level of functioning, 10% achieving significant and lasting improvement, and 30% showing some improvement with intermittent relapses

Question 31

Name the 4 evaluative points for the validity of the classification and diagnosis of SZ

Answer 31

1) Comorbidity and medical complications
2) Comorbidity and suicide risk
3) Ethnicity
4) Symptoms

Question 32

Outline comorbidity and medical complications for the validity of the classification and diagnosis of SZ

Answer 32

Poor levels of functioning may be less the result and more to do with untreated comorbid physical disorders

Question 33

What is the study associated with comorbidity and medical complications for the validity of the classification and diagnosis of SZ?

Answer 33

Weber (09)

Question 34

Outline Weber (09)

Answer 34

Examined nearly 6 million hospital discharge records to calculate comorbidity rates - psychiatric and behaviour related diagnoses accounted for 45% of comorbidity and also found evidence of many comorbid non-psychiatric disorders - many patients with primary diagnosis were also diagnosed with medical problems like asthma, hypertension and type 2 diabetes so concluded a consequence of being diagnosed is tend receive lower standard of medical care, which in turn adversely affects their prognosis

Question 35

Outline comorbidity and suicide risk for the validity of the classification and diagnosis of SZ

Answer 35

People with SZ pose relatively high risk for suicide, with comorbid depression being major cause for suicidal behaviour

Question 36

What is the study associated with comorbidity and suicide risk for the validity of the classification and diagnosis of SZ

Answer 36

Kessler (94)

Question 37

Outline Kessler (94)

Answer 37

Rate for attempted suicide rose from 1% for those with SZ alone to 40% for those with at least one lifetime comorbid mood disorder

Question 38

Outline ethnicity for the validity of the classification and diagnosis of SZ

Answer 38

In UK, rates of SZ among African-Caribbeans are much higher when compared with white populations, some explained as result of poor housing, higher rates of unemployment and social isolation - also remains possibility that misdiagnosis may result from factors like cultural differences in language and mannerisms and difficulties in relating between black patients and white clinicians

Question 39

What is the study associated with ethnicity for the validity of the classification and diagnosis of SZ?

Answer 39

Harrison (97)

Question 40

Outline Harrison (97)

Answer 40

Reported incidence rate for SZ was 8 times higher for AC groups (46.7 per 100,000) than for white groups (5.7 per 100,000)

Question 41

Outline symptoms for the validity of the classification and diagnosis of SZ

Answer 41

Many symptoms of SZ also found in many other disorders like depression and bipolar disorder so less valid

Question 42

What is the study associated with symptoms for the validity of the classification and diagnosis of SZ

Answer 42

Ellason & Ross (95)

Question 43

Outline Ellason & Ross (95)

Answer 43

People with dissociative identity disorder actually have more SZ symptoms than those diagnosed with SZ