Classification and Diagnosis Issues Flashcards
Kleitman’s 3 factors affecting the reliability of diagnosis
Difference: in procedures (classification systems), between clinicians (subjective interpretation), between patients
Improvements of reliability over time: DSM 2
Cause of low reliability, 2 studies
Vague
Beck 1967: 54% inter-rate reliability
Cooper 1972: low agreement between US and Britain
Improvement of reliability over time: DSM 3
What year? 1 study?
1980
American Psychiatric Association (APA) = 81% consistent diagnosis
Improvements of reliability over time: DSM 4
1 study? Sub-types of schizophrenia?
Cheniaux (2009): kappa statisics 0.59 DSM 4, 0.61 between DSM 4 and ICD 10
Improvements of reliability over time: DSM 5
APA finding? Comparison to other conditions?
APA: kappa = 0.46 (lower but used real-life setting)
alcoholism, binge eating and bipolar = similar stats. PTSD, autism and ADHD = higher
What is reliability? What is validity?
Consistency
Truth
What does the validity of a diagnosis rely on? (2) What affects these two things?
reliability of diagnosis and validity of classification
reliability of classification
What is the normal inter-rater reliability we would expect?
Study on this?
0.7 agrrement
Mojtabi and Nicholson 1995: 0.4 between clinicians on whether hallucinations were ‘bizarre’
Why would patients present differently? (2)
Their mood and the variability of their symptoms
Why would patients present differently to different doctors? (3)
Demographic of the doctor (gender/age/ethnicity), personality (warmth) and skill in questioning
Define descriptive validity
The symptoms make the condition clearly distinguishable from other conditions
Define aetiological validity
The causes or mechanisms of the condition is clear
Define predictive validity
For a well defined illness, the progression is known and reaction to treatment can be predicted
Which is more likely to produce a Type 1 or 2 error: DSM or ICD?
ICD: Type 1 (false positive) more likely as symptoms don’t have to have been present for more than 1 month, DSM more likely type 2 error (false negative)
What is cluster analysis?
Investigates whether symptoms of an illness co occur (if having one symptom is associated with having others) If you have one symptom of schizophrenia you should be more likely to have the other symptoms than other people
Who conducted cluster analysis in schizophrenia?
Liddle: 3 clusters of symptoms: positive, negative and symptoms of cognitive disorganisation
What issue does schizophrenia have with descriptive validity?
schizophrenia and depression often blurred because they share negative symptoms, suggests 2 disorders are not clearly distinguished enough
What research seems to prove that schizophrenia has aetiological validity?
Howes and Kapur 2008: pre-synaptic dysregulation of dopamine is involved in all cases of schizophrenia that have psychotic symptoms, this is the common mechanism, initial cause of dysregulation may be different
What would increase aetiological validity in schizophrenia?
redefine schizophrenia based on the 3 clusters -single mechanism for each cluster
What would increase aetiological validity in schizophrenia?
redefine schizophrenia based on the 3 clusters -single mechanism for each cluster
What feature of schizophrenia reduces its predictive validity?
variability in prognosis: 1/3 patients remain chronically ill, 1/3 recover from initial illness, 1/3 have period of illness and periods of being well
What id difficult to predict for schizophrenic patients?
How they will respond to drug treatment, all drugs that have any effectiveness affect dopamine receptors, some drugs also affect serotonin receptors
Which psychologist documented a case study of the consequences of false positives?
Swartz 2001: 46yrs women, treating as having schizophrenia for 10yrs, EEG revealed epilepsy though she had had treatment with antipsychotics, most appropriate treatment withheld for 10yrs
What research shows the effect of false-positive schizophrenia diagnosis on those with Asperger syndrome?
Perlman 2000: cases of chronic undifferentiated schizophrenia but didn’t fit criteria right, unnecessary antipsychotics without any positive symptoms, actually has Asperger syndrome
What are the other affects of a false positive diagnosis?
the label schizophrenia may become part of identity, in self-fulfilling prophecy may start to demonstrate symptoms which reinforces the diagnosis
What were the findings of Rosenhan’s 1973 study?
The fake schizophrenic patients behaviour was all interpreted based on their original diagnosis: making notes = writing behaviour which was considered abnormal, arriving early for lunch = oral inquisitive
What are the consequences of a false negative diagnosis?
schizophrenics not given treatment so left t deal with their illness, symptoms worsen, no support, vulnerability
