Discuss validity and reliability of diagnosis

Discuss validity and reliability of diagnosis. (22)

Discuss (22) – A considered and balanced review, including a range of arguments, factors or hypothesis. Opinions and conclusions presented clearly supported by appropriate evidence.

Diagnosis

Purpose of diagnosis

Identify abnormal disorders so treatment can be applied accordingly.
Provides investigation opportunities into the etiologies of disorders.

Methods of diagnosis

Biological tests
Brain scans
Blood tests
Psychological tests
IQ test
Personality test
Cognitive tasks
Interviews
Observations
Reference to the Classification System (e.g. DSM, ICD)

Classification/Diagnosis systems

Classification systems are suppose to be objective.
Traditional medical model in psychiatry is now assumed to be reductionist.
Most psychiatrists use a biopsychosocial approach in diagnosis and treatment.
Diagnose based on symptoms.
Affective (mood) symptoms
Behavioural symptoms
Cognitive (thought process) symptoms
Somatic (physical) symptoms
Based heavily upon abnormal experiences and belief reported by patients.
Agreed by a team of professionals.
Explains why Classification/Diagnosis systems are often updated and revised.

Strengths of classification systems

Statistical diagnosis
Quantifiable
Ability to identify disorders based on symptoms
Therefore suitable treatment can be applied

Weakness of classification systems

Ethical consideration is the main weakness of Classification systems
The effects of labeling
Leads to stigmatisation
Prejudice and discrimination
Self labeling can lead to Self-fulfilling prophecy
Person diagnosed with disorder act according to the label

Reliability

Whether the same disorder is diagnosed every time.
Inter-rater reliability: whether different diagnosticians get the same diagnosis. ie. how objective the diagnostic criteria is.
Test-retest: whether repeating the diagnosis will give a different result between each time.

Cooper et al. – New York London Diagnosis
Description	An identical video clip of a patient was shown to psychiatrists from New York and London. Psychiatrists from New York had a higher likelihood of diagnosing schizophrenia. Psychiatrists from London were more likely to diagnose mania or depression.

Beck – Psychiatrists agreement
Description	Agreement between two psychiatrists on diagnosis for 153 patients was 54%. The was due to the vagueness in criteria for diagnosis and; The different process for diagnosis.

Validity

Does the diagnosis process measure a real pattern of symptoms.
Can effective treatment be administered based on the diagnosis.
Are there biases in diagnostics?
Confirmation bias: Psychiatrists puts emphasis on factors that hint patient’s disorders and overlooks other possible factors.
FAE: Over attributing the causes to the dispositional factors.
Self-fulfilling prophecy: Patient gets labeled as having a certain disorder and act according to the label

Rosenhan – On being sane in insane places (I)
[A]	Challenge the reliability and validity of diagnosis. Investigate the effects of labeling.
[P]	Eight participants, 5 male and 3 female, attempted to gain admittance in the hospital’s psychiatric ward. Participants phoned up the hospital for a diagnosis appointment. They all used a fake name and job (to protect their future health and employment record <- ethical considerations). All the participants claimed that they were hearing voices. These are existential symptoms which arise from concerns about how meaningless your life is. They were chosen because there were no mention of existential psychosis in the literature. After admitted into the psychiatric ward, they stopped showing the pseudo-symptoms and acted like they would ordinarily. Participants started making notes about their life and the way the were treated in the ward. Initially, they had to write in secret because they are scared wardens might find out. Afterwards, they realized no one cared so they did it more publicly. Participants asked the staffs for a favor that tested the behaviour of staff towards patients, which took the following form: ‘Pardon me, Mr/Mrs/Dr X, could you tell me when I will be presented at the staff meeting?’. (or ‘…when am I likely to be discharged?’) Similar procedure was carried out with Students at Stanford University with students asking university staff a simple question. Results were used to compare.
[F]	All pseudo-patients disliked the environment and wanted to be discharged immediately. All participants were “diagnosed” with schizophrenia. No staff suspected their sanity. Patients in the ward, however, did suspect the sanity of some of them, and reacted vigorously. For example: ‘You’re not crazy. You’re a journalist, or a professor. You’re checking up on the hospital’. Patients were deprived of almost all human rights e.g. privacy Medical records were not kept confidential Hygiene was poor Wardens would be brutal to patients when no other warden was around Indicates that patients had no credibility, but wardens do. Time spent with nurses, psychiatrist etc. averaged under 7 minutes per day.
[C]	There is an enormous overlap in the behaviours of the sane and the insane. We all feel depressed sometimes, have moods, become angry and so forth. But in the context of a psychiatric hospital, these everyday human experiences and behaviours were interpreted as pathological. Regarding the favor asked, most pseudo patients were ignored. where as all questions were addressed in the Stanford University experiment. Experience of hospitalisation for the pseudo patients was one of depersonalisation and powerlessness.
[E]	Field experiment/covert observation, high ecological validity. Can argue that experiment is low in ecological validity, psychiatrist don’t usually diagnose “pseudo-patients”. It is expected that the person will have some sort of disorder if they seek diagnosis. Psychiatrists would normally play safe in their diagnosis. Because there is always an outcry when a patient is let out of psychiatric care and gets into trouble. Always a higher likelihood of diagnosing a normal person sick than a sick person normal. DSM-II was in used then, an updated version of the DSM (DSM-IV) used now has more sophisticated descriptions for diagnosis. Showed that patients suffering from psychological disorders experienced. Labeling and stigmatization Depersonalisation Discrimination Controversial study. Deception was involved, unethical.

Temerline – Authority on diagnosis
[A]	Investigate the effect of authority on diagnosis.
[P]	2 groups of participants listened to the same taped interview of a person describing their own life. The person talked about a seemingly normal life (i.e. happy marriage, enjoyment at work). A respected figure in psychiatry then told 1 group of participants that he thinks the man was psychologically health. He told the other group that he thinks the person was a psychotic. Participants were then asked to judge the person’s mental health.
[F]	Those who were told the participants were normal gave a “normal” diagnostic. Those who were told that the participant was a psychotic agreed with that diagnosis.
[C]	Shows that someone with authority and expertise can have stung influence on the way people are perceived.
[E]	The story of the taped person was hypothetical. Might have gave a different response if the person was physically present. Difficult to gather information about real-life roles and interactions between psychiatrists and patients. May break ethical guidelines (Privacy and Confidentiality). Opinions on causes and treatment may differ between psychiatrists.