Zusammenfassung der Ressource
Classification + Diagnosis of Schizophrenia
- Reliability
- A01
- Refers to consistency of measuring instrument, such as a questionnaire or
scale, to assess, for example, severity of their Sz symptoms
- R can be measured in terms of whether 2 independent assessors give
similar diagnosis (inter-rater r) or whether tests used to deliver these
diagnosis are consistent over time (test-retest r)
- A02
- Unreliable sympotms
- To be diagnosed w/ Sz, a person only has to have 1 of
characteristic sympotms if their 'delusions are bizarre'
- Mojtabi + Nicholson
- 50 senior US psychiatrists were asked to differentiate between 'bizarre' + 'non-bizarre' delusions
- They produce inter-reliability correlations of only around +40, forcing researchers to conclude even this central diagnostic requirement
lacks sufficient reliability for it to be reliable method of distinguishing between Sz + non-Sz patients
- Cultural differences in diagnosis
- Copeland
- Gave 134 US + 194 British psychiatrists
a description of a patient
- 69% of US psychiatrists diagnosed Sz but only 2% of British psychiatrists gave same diagnosis
- Reliability - Rosenhan
- A01
- Situational factors are supposedly more important than actual
characteristics of a person when it comes to diagnosis
- A02
- Demonstrated effect of 'situational' factors in study
'being sane in insane places'
- Pseudo patients were sent into institutions + were classified as Sz
- Claimed they heard an unfamiliar voice saying words 'empty', 'hollow' + 'thud'
- Throughout stay, none of the staff
recognised they were actually normal
- Some of them made notes of what was occurring while
omitted - staff took this as part of their Sz
- Suggests situation is more important than actual person
- Complication made more apparent...
- Follow-up study
- R warned hospitals of his intention to
send out more 'pseudo patients'
- Resulted in 21% detection rate
- Although none actually presented themselves
- Validity
- A01
- Refers to extent a diagnosis represents something
that is real + distinct from other disrders
- + extent a classification system (ICD or
DSM) measures what it claims to
measure
- R + V inextricably linked because diagnosis
cannot be valid if it isn't reliable
- A02
- Comorbidity
- Refers to extent two (or more) conditions co-occur
- Commonly found among patients diagnosed w/ Sz
- Medical complications
- Poor levels of functioning found in many Sz may be less result of
psychiatric disorder + more to do w/ untreated comorbid physical disorders
- Weber et al
- Examined nearly 6 million
hospital discharge records
- Psychiatric + behaviour related diagnosis accounted for 45% of C
- Many patients w/ primary diagnosis of Sz also diagnosed w/ med probs. -
asthma, hypertension + type 2 diabetes
- Concluded consequence of being diagnosed w/ psychiatric
disorder such as Sz is patients tend to receive lower standard of
med care, which in adversely affects prognosis
- Also found evidence of many comorbid
non-psychiatric diagnoses
- Suicide risk
- People w/ Sz pose relatively high risk for S, w/ comorbid
depression being major cause for suicidal behaviour
- Among patients in National Comorbidity Survey, rate for attempted
suicide rose from 1% of those w/ Sz alone to 40% for those w/ at least 1
lifetime comorbid mood disorder
- Predictive validity
- A01
- People diagnosed as Sz rarely share same symptoms, nor is there
evidence they share same outcomes
- Prognosis for patients varies w/ about 20% recovering their previous level of
functioning, 10% achieving significant + lasting improvement + about 30%
showing some improvement w/ intermittent relapses
- Diagnosis of Sz, therefore, has little PV - some people never
appear to recover from disorder, but many do
- A02
- Symptoms
- Despite belief identification of symptoms of Sz would make
for more valid diagnoses of disorder, many symptoms also
found in other disorders
- Ellason + Ross
- People w/ dissociative identity disorder (DID) actually
have more Sz symptoms than people diagnosed as being
Sz!
- Other factors linked to prognosis of disorder
- Gender, ethnicity + psychosocial factors
- M are supposedly more at risk than w
- Harrison et al
- Reported incidence rate for Sz was 8 times higher for
African-Caribbean groups than for white groups
- Result of poor housing, higher rates of
unemployment + social isolation
- Or result of cultural differences in language + mannerisms +
difficulties in relating between black patients + white
clinicians